diff --git a/composer.json b/composer.json
index e263791..27949d0 100644
--- a/composer.json
+++ b/composer.json
@@ -40,11 +40,8 @@
         "concurrent-php/async-api": "dev-master"
     },
     "require-dev": {
-        "amphp/phpunit-util": "dev-ext-async",
-        "react/promise": "^2",
-        "friendsofphp/php-cs-fixer": "^2.3",
-        "phpunit/phpunit": "^6.0.9",
-        "phpstan/phpstan": "^0.8.5"
+        "friendsofphp/php-cs-fixer": "^2.13",
+        "phpunit/phpunit": "^6.0.9"
     },
     "autoload": {
         "psr-4": {
diff --git a/lib/Cancellation/CancelledException.php b/lib/Cancellation/CancelledException.php
deleted file mode 100644
index 6d95f8a..0000000
--- a/lib/Cancellation/CancelledException.php
+++ /dev/null
@@ -1,17 +0,0 @@
-<?php
-
-namespace Amp\Cancellation;
-
-/**
- * Will be thrown in case an operation is cancelled.
- *
- * @see Token
- * @see CancellationTokenSource
- */
-class CancelledException extends \Exception
-{
-    public function __construct(string $message = "The operation was cancelled", \Throwable $previous = null)
-    {
-        parent::__construct($message, 0, $previous);
-    }
-}
diff --git a/lib/Cancellation/NullToken.php b/lib/Cancellation/NullToken.php
deleted file mode 100644
index 60be57a..0000000
--- a/lib/Cancellation/NullToken.php
+++ /dev/null
@@ -1,53 +0,0 @@
-<?php
-
-namespace Amp\Cancellation;
-
-/**
- * A NullCancellationToken can be used to avoid conditionals to check whether a token has been provided.
- *
- * Instead of writing
- *
- * ```php
- * if ($token) {
- *     $token->throwIfRequested();
- * }
- * ```
- *
- * potentially multiple times, it allows writing
- *
- * ```php
- * $token = $token ?? new NullCancellationToken;
- *
- * // ...
- *
- * $token->throwIfRequested();
- * ```
- *
- * instead.
- */
-final class NullToken implements Token
-{
-    /** @inheritdoc */
-    public function subscribe(callable $callback): string
-    {
-        return "null-token";
-    }
-
-    /** @inheritdoc */
-    public function unsubscribe(string $id): void
-    {
-        // nothing to do
-    }
-
-    /** @inheritdoc */
-    public function isRequested(): bool
-    {
-        return false;
-    }
-
-    /** @inheritdoc */
-    public function throwIfRequested(): void
-    {
-        // nothing to do
-    }
-}
diff --git a/lib/Cancellation/TimeoutToken.php b/lib/Cancellation/TimeoutToken.php
deleted file mode 100644
index 34c0d6c..0000000
--- a/lib/Cancellation/TimeoutToken.php
+++ /dev/null
@@ -1,73 +0,0 @@
-<?php
-
-namespace Amp\Cancellation;
-
-use Amp\Loop;
-use Amp\TimeoutException;
-
-/**
- * A TimeoutCancellationToken automatically requests cancellation after the timeout has elapsed.
- */
-final class TimeoutToken implements Token
-{
-    /** @var string */
-    private $watcher;
-
-    /** @var Token */
-    private $token;
-
-    /**
-     * @param int $timeout Milliseconds until cancellation is requested.
-     */
-    public function __construct(int $timeout)
-    {
-        $source = new TokenSource;
-        $this->token = $source->getToken();
-
-        $this->watcher = Loop::delay($timeout, static function () use ($source) {
-            $source->cancel(new TimeoutException);
-        });
-
-        Loop::unreference($this->watcher);
-    }
-
-    /**
-     * Cancels the delay watcher.
-     */
-    public function __destruct()
-    {
-        Loop::cancel($this->watcher);
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function subscribe(callable $callback): string
-    {
-        return $this->token->subscribe($callback);
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function unsubscribe(string $id): void
-    {
-        $this->token->unsubscribe($id);
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function isRequested(): bool
-    {
-        return $this->token->isRequested();
-    }
-
-    /**
-     * {@inheritdoc}
-     */
-    public function throwIfRequested(): void
-    {
-        $this->token->throwIfRequested();
-    }
-}
diff --git a/lib/Cancellation/Token.php b/lib/Cancellation/Token.php
deleted file mode 100644
index a0ddab7..0000000
--- a/lib/Cancellation/Token.php
+++ /dev/null
@@ -1,49 +0,0 @@
-<?php
-
-namespace Amp\Cancellation;
-
-/**
- * Cancellation tokens are simple objects that allow registering handlers to subscribe to cancellation requests.
- */
-interface Token
-{
-    /**
-     * Subscribes a new handler to be invoked on a cancellation request.
-     *
-     * This handler might be invoked immediately in case the token has already been cancelled. Returned generators will
-     * automatically be run as coroutines. Any unhandled exceptions will be throw into the event loop.
-     *
-     * @param callable $callback Callback to be invoked on a cancellation request. Will receive a `CancelledException`
-     * as first argument that may be used to fail the operation's promise.
-     *
-     * @return string Identifier that can be used to cancel the subscription.
-     */
-    public function subscribe(callable $callback): string;
-
-    /**
-     * Unsubscribes a previously registered handler.
-     *
-     * The handler will no longer be called as long as this method isn't invoked from a subscribed callback.
-     *
-     * @param string $id
-     *
-     * @return void
-     */
-    public function unsubscribe(string $id): void;
-
-    /**
-     * Returns whether cancellation has been requested yet.
-     *
-     * @return bool
-     */
-    public function isRequested(): bool;
-
-    /**
-     * Throws the `CancelledException` if cancellation has been requested, otherwise does nothing.
-     *
-     * @return void
-     *
-     * @throws CancelledException
-     */
-    public function throwIfRequested(): void;
-}
diff --git a/lib/Cancellation/TokenSource.php b/lib/Cancellation/TokenSource.php
deleted file mode 100644
index 1f8a6f2..0000000
--- a/lib/Cancellation/TokenSource.php
+++ /dev/null
@@ -1,119 +0,0 @@
-<?php
-
-namespace Amp\Cancellation;
-
-/**
- * A cancellation token source provides a mechanism to cancel operations.
- *
- * Cancellation of operation works by creating a cancellation token source and passing the corresponding token when
- * starting the operation. To cancel the operation, invoke `CancellationTokenSource::cancel()`.
- *
- * Any operation can decide what to do on a cancellation request, it has "don't care" semantics. An operation SHOULD be
- * aborted, but MAY continue. Example: A DNS client might continue to receive and cache the response, as the query has
- * been sent anyway. An HTTP client would usually close a connection, but might not do so in case a response is close to
- * be fully received to reuse the connection.
- *
- * **Example**
- *
- * ```php
- * $tokenSource = new CancellationTokenSource;
- * $token = $tokenSource->getToken();
- *
- * $response = yield $httpClient->request("https://example.com/stream", $token);
- * $responseBody = $response->getBody();
- *
- * while (($chunk = yield $response->read()) !== null) {
- *     // consume $chunk
- *
- *     if ($noLongerInterested) {
- *         $cancellationTokenSource->cancel();
- *         break;
- *     }
- * }
- * ```
- *
- * @see Token
- * @see CancelledException
- */
-final class TokenSource
-{
-    private $token;
-    private $onCancel;
-
-    public function __construct()
-    {
-        $this->token = new class($this->onCancel) implements Token {
-            /** @var string */
-            private $nextId = "a";
-
-            /** @var callable[] */
-            private $callbacks = [];
-
-            /** @var \Throwable|null */
-            private $exception;
-
-            public function __construct(&$onCancel)
-            {
-                $onCancel = function (\Throwable $exception) {
-                    $this->exception = $exception;
-
-                    $callbacks = $this->callbacks;
-                    $this->callbacks = [];
-
-                    foreach ($callbacks as $callback) {
-                        $callback($this->exception);
-                    }
-                };
-            }
-
-            public function subscribe(callable $callback): string
-            {
-                $id = $this->nextId++;
-
-                if ($this->exception) {
-                    $callback($this->exception);
-                } else {
-                    $this->callbacks[$id] = $callback;
-                }
-
-                return $id;
-            }
-
-            public function unsubscribe(string $id): void
-            {
-                unset($this->callbacks[$id]);
-            }
-
-            public function isRequested(): bool
-            {
-                return $this->exception !== null;
-            }
-
-            public function throwIfRequested(): void
-            {
-                if ($this->exception !== null) {
-                    throw $this->exception;
-                }
-            }
-        };
-    }
-
-    public function getToken(): Token
-    {
-        return $this->token;
-    }
-
-    /**
-     * @param \Throwable|null $previous Exception to be used as the previous exception to CancelledException.
-     */
-    public function cancel(\Throwable $previous = null): void
-    {
-        if ($this->onCancel === null) {
-            return;
-        }
-
-        $onCancel = $this->onCancel;
-        $this->onCancel = null;
-        $onCancel(new CancelledException("The operation was cancelled", $previous));
-    }
-}
diff --git a/lib/Emitter.php b/lib/Emitter.php
index a833dec..abacd89 100644
--- a/lib/Emitter.php
+++ b/lib/Emitter.php
@@ -2,7 +2,6 @@
 
 namespace Amp;
 
-use Amp\Cancellation\CancelledException;
 use Concurrent\Awaitable;
 use Concurrent\Deferred;
 use Concurrent\Task;
@@ -58,7 +57,7 @@ final class Emitter
             public $waiting;
         };
 
-        $this->iterator = (static function () use (&$state) {
+        $this->iterator = (static function () use ($state) {
             while (true) {
                 if (isset($state->backpressure[$state->position])) {
                     /** @var Deferred $deferred */
@@ -92,7 +91,7 @@ final class Emitter
     public function __destruct()
     {
         if (!$this->state->complete) {
-            $this->fail(new CancelledException("The operation was cancelled, because the emitter was garbage collected without completing, created in {$this->createFile}:{$this->createLine}"));
+            $this->fail(new \Error("The emitter was garbage collected without completing, created in {$this->createFile}:{$this->createLine}"));
         }
     }
 
@@ -106,7 +105,7 @@ final class Emitter
     public function extractIterator(): \Iterator
     {
         if ($this->iterator === null) {
-            throw new \Error("The emitter's iterator can only be extracted once!");
+            throw new \Error("The emitter's iterator can only be extracted once");
         }
 
         $iterator = $this->iterator;
@@ -131,7 +130,7 @@ final class Emitter
         }
 
         $this->state->values[] = $value;
-        $this->state->backpressure[] = $pressure = new Deferred;
+        $this->state->backpressure[] = $backpressure = new Deferred;
 
         if ($this->state->waiting !== null) {
             /** @var Deferred $waiting */
@@ -140,7 +139,7 @@ final class Emitter
             $waiting->resolve(true);
         }
 
-        Task::await($pressure->awaitable());
+        Task::await($backpressure->awaitable());
     }
 
     /**
@@ -149,7 +148,7 @@ final class Emitter
     public function complete(): void
     {
         if ($this->state->complete) {
-            throw new \Error("Emitters has already been " . ($this->state->exception === null ? "completed" : "failed"));
+            throw new \Error("Emitter has already been " . ($this->state->exception === null ? "completed" : "failed"));
         }
 
         $this->state->complete = true;
@@ -170,7 +169,7 @@ final class Emitter
     public function fail(\Throwable $reason): void
     {
         if ($this->state->complete) {
-            throw new \Error("Emitters has already been " . ($this->state->exception === null ? "completed" : "failed"));
+            throw new \Error("Emitter has already been " . ($this->state->exception === null ? "completed" : "failed"));
         }
 
         $this->state->complete = true;
diff --git a/lib/Struct.php b/lib/Struct.php
index ff69beb..5dd3ae1 100644
--- a/lib/Struct.php
+++ b/lib/Struct.php
@@ -5,8 +5,8 @@ namespace Amp;
 /**
  * A "safe" struct trait for public property aggregators.
  *
- * This trait is intended to make using public properties a little safer by throwing when
- * nonexistent property names are read or written.
+ * This trait is intended to make using public properties a little safer by throwing when nonexistent property names are
+ * read or written.
  */
 trait Struct
 {
@@ -16,6 +16,13 @@ trait Struct
      */
     private $__propertySuggestThreshold = 70;
 
+    public function __isset(string $property)
+    {
+        throw new \Error(
+            $this->generateStructPropertyError($property)
+        );
+    }
+
     public function __get(string $property)
     {
         throw new \Error(
@@ -30,13 +37,20 @@ trait Struct
         );
     }
 
+    public function __unset(string $property)
+    {
+        throw new \Error(
+            $this->generateStructPropertyError($property)
+        );
+    }
+
     private function generateStructPropertyError(string $property): string
     {
         $suggestion = $this->suggestPropertyName($property);
-        $suggestStr = ($suggestion == "") ? "" : " ... did you mean \"{$suggestion}?\"";
+        $suggestStr = $suggestion === "" ? "" : " ... did you mean '{$suggestion}'?";
 
         return \sprintf(
-            "%s property \"%s\" does not exist%s",
+            "%s property '%s' does not exist%s",
             \str_replace("\0", "@", \get_class($this)), // Handle anonymous class names.
             $property,
             $suggestStr
diff --git a/lib/TimeoutException.php b/lib/TimeoutException.php
index 8f65d2c..cfebeb5 100644
--- a/lib/TimeoutException.php
+++ b/lib/TimeoutException.php
@@ -3,7 +3,7 @@
 namespace Amp;
 
 /**
- * Thrown if a promise doesn't resolve within a specified timeout.
+ * Thrown if an awaitable doesn't resolve within a specified timeout.
  *
  * @see \Amp\timeout()
  */
diff --git a/lib/functions.php b/lib/functions.php
index 2aca47a..07a3a9b 100644
--- a/lib/functions.php
+++ b/lib/functions.php
@@ -43,11 +43,11 @@ namespace Amp
      * @param Awaitable $awaitable Awaitable to which the timeout is applied.
      * @param int       $timeout Timeout in milliseconds.
      *
-     * @return Awaitable
+     * @return mixed
      *
      * @throws TimeoutException
      */
-    function timeout(Awaitable $awaitable, int $timeout): Awaitable
+    function timeout(Awaitable $awaitable, int $timeout)
     {
         $timeoutAwaitable = Task::async(function () use ($timeout) {
             $timer = new Timer($timeout);
@@ -62,16 +62,11 @@ namespace Amp
     function some(array $awaitables, int $required = 1)
     {
         if ($required < 0) {
-            throw new \Error("Number of promises required must be non-negative");
+            throw new \Error("Number of awaitables required must be non-negative, was '{$required}'");
         }
 
-        $pending = \count($awaitables);
-
-        if ($required > $pending) {
-            throw new \Error("Too few promises provided");
-        }
         if (empty($awaitables)) {
-            return [[], []];
+            throw new \Error("Array of awaitables can't be empty");
         }
 
         $values = [];
@@ -88,11 +83,7 @@ namespace Amp
             $key,
             ?\Throwable $error,
             $value
-        ) use (
-            &$values,
-            &$errors,
-            $required
-        ) {
+        ) use (&$values, &$errors, $required) {
             if ($error) {
                 $errors[$key] = $error;
                 unset($values[$key]);
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 70319e1..f1c7796 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,17 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<phpunit
-        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-        xsi:noNamespaceSchemaLocation="http://schema.phpunit.de/6.0/phpunit.xsd"
-        backupGlobals="false"
-        backupStaticAttributes="false"
-        bootstrap="vendor/autoload.php"
-        colors="true"
-        convertErrorsToExceptions="true"
-        convertNoticesToExceptions="true"
-        convertWarningsToExceptions="true"
-        processIsolation="false"
-        stopOnFailure="false"
->
+<phpunit bootstrap="vendor/autoload.php" colors="true" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="http://schema.phpunit.de/6.0/phpunit.xsd">
     <testsuites>
         <testsuite name="Main">
             <directory>test</directory>
@@ -25,7 +14,4 @@
             <directory suffix=".php">lib</directory>
         </whitelist>
     </filter>
-    <listeners>
-        <listener class="Amp\PHPUnit\LoopReset"/>
-    </listeners>
 </phpunit>
diff --git a/test/Cancellation/CancellationTest.php b/test/Cancellation/CancellationTest.php
deleted file mode 100644
index 3ce010c..0000000
--- a/test/Cancellation/CancellationTest.php
+++ /dev/null
@@ -1,97 +0,0 @@
-<?php
-
-namespace Amp\Test;
-
-use Amp\Cancellation\Token;
-use Amp\Cancellation\TokenSource;
-use Amp\Emitter;
-use Amp\PHPUnit\TestCase;
-use Amp\PHPUnit\TestException;
-use Concurrent\Task;
-use function Amp\rethrow;
-
-class CancellationTest extends TestCase
-{
-    private function createIterator(Token $token): \Iterator
-    {
-        $emitter = new Emitter;
-
-        rethrow(Task::async(function () use ($emitter, $token) {
-            $running = true;
-
-            $token->subscribe(function () use (&$running) {
-                $running = false;
-            });
-
-            $i = 0;
-            while ($running) {
-                $emitter->emit($i++);
-            }
-
-            $emitter->complete();
-        }));
-
-        return $emitter->extractIterator();
-    }
-
-    public function testCancellationCancelsIterator(): void
-    {
-        $source = new TokenSource;
-        $current = null;
-
-        foreach ($this->createIterator($source->getToken()) as $current) {
-            $this->assertInternalType("int", $current);
-
-            if ($current === 3) {
-                $source->cancel();
-            }
-        }
-
-        $this->assertSame(3, $current);
-    }
-
-    public function testUnsubscribeWorks(): void
-    {
-        $cancellationSource = new TokenSource;
-
-        $first = $cancellationSource->getToken()->subscribe(function () {
-            $this->fail("Callback has been called");
-        });
-
-        $cancellationSource->getToken()->subscribe(function () {
-            $this->assertTrue(true);
-        });
-
-        $cancellationSource->getToken()->unsubscribe($first);
-
-        $cancellationSource->cancel();
-    }
-
-    public function testThrowingCallback(): void
-    {
-        $this->expectException(TestException::class);
-
-        $cancellationSource = new TokenSource;
-        $cancellationSource->getToken()->subscribe(function () {
-            throw new TestException(__LINE__);
-        });
-
-        $cancellationSource->cancel();
-    }
-
-    public function testDoubleCancelOnlyInvokesOnce(): void
-    {
-        $cancellationSource = new TokenSource;
-        $cancellationSource->getToken()->subscribe($this->createCallback(1));
-
-        $cancellationSource->cancel();
-        $cancellationSource->cancel();
-    }
-
-    public function testCalledIfSubscribingAfterCancel(): void
-    {
-        $cancellationSource = new TokenSource;
-        $cancellationSource->cancel();
-        $cancellationSource->getToken()->subscribe($this->createCallback(1));
-    }
-}
diff --git a/test/Cancellation/TimeoutTokenTest.php b/test/Cancellation/TimeoutTokenTest.php
deleted file mode 100644
index c8c5613..0000000
--- a/test/Cancellation/TimeoutTokenTest.php
+++ /dev/null
@@ -1,37 +0,0 @@
-<?php
-
-namespace Amp\Test\Cancellation;
-
-use Amp\Cancellation\CancelledException;
-use Amp\Cancellation\TimeoutToken;
-use Amp\Loop;
-use Amp\TimeoutException;
-use PHPUnit\Framework\TestCase;
-use function Amp\delay;
-
-class TimeoutTokenTest extends TestCase
-{
-    public function testTimeout(): void
-    {
-        $token = new TimeoutToken(10);
-
-        $this->assertFalse($token->isRequested());
-        delay(20);
-        $this->assertTrue($token->isRequested());
-
-        try {
-            $token->throwIfRequested();
-            $this->fail("Must throw exception");
-        } catch (CancelledException $exception) {
-            $this->assertInstanceOf(TimeoutException::class, $exception->getPrevious());
-        }
-    }
-
-    public function testWatcherCancellation(): void
-    {
-        $token = new TimeoutToken(1);
-        $this->assertSame(1, Loop::getInfo()["delay"]["enabled"]);
-        unset($token);
-        $this->assertSame(0, Loop::getInfo()["delay"]["enabled"]);
-    }
-}
diff --git a/test/Loop/DriverStateTest.php b/test/Loop/DriverStateTest.php
deleted file mode 100644
index f079828..0000000
--- a/test/Loop/DriverStateTest.php
+++ /dev/null
@@ -1,57 +0,0 @@
-<?php
-
-namespace Amp\Test\Loop;
-
-use Amp\Loop;
-use Amp\Loop\Driver;
-use PHPUnit\Framework\TestCase;
-
-class DriverStateTest extends TestCase
-{
-    /** @var Driver */
-    private $loop;
-
-    protected function setUp()
-    {
-        $this->loop = $this->getMockForAbstractClass(Driver::class);
-    }
-
-    /** @test */
-    public function defaultsToNull()
-    {
-        $this->assertNull($this->loop->getState("foobar"));
-    }
-
-    /**
-     * @test
-     * @dataProvider provideValues
-     */
-    public function getsPreviouslySetValue($value)
-    {
-        $this->loop->setState("foobar", $value);
-        $this->assertSame($value, $this->loop->getState("foobar"));
-    }
-
-    /**
-     * @test
-     * @dataProvider provideValues
-     */
-    public function getsPreviouslySetValueViaAccessor($value)
-    {
-        Loop::setState("foobar", $value);
-        $this->assertSame($value, Loop::getState("foobar"));
-    }
-
-    public function provideValues()
-    {
-        return [
-            ["string"],
-            [42],
-            [1.001],
-            [true],
-            [false],
-            [null],
-            [new \StdClass],
-        ];
-    }
-}
diff --git a/test/Loop/DriverTest.php b/test/Loop/DriverTest.php
deleted file mode 100644
index e024111..0000000
--- a/test/Loop/DriverTest.php
+++ /dev/null
@@ -1,1620 +0,0 @@
-<?php
-
-namespace Amp\Test\Loop;
-
-use Amp\Loop;
-use Amp\Loop\Driver;
-use Amp\Loop\InvalidWatcherError;
-use Amp\Loop\UnsupportedFeatureException;
-use Amp\PHPUnit\TestCase;
-use Amp\PHPUnit\TestException;
-use Concurrent\Deferred;
-use function Amp\delay;
-
-if (!\defined("SIGUSR1")) {
-    \define("SIGUSR1", 30);
-}
-if (!\defined("SIGUSR2")) {
-    \define("SIGUSR2", 31);
-}
-
-if (!\defined("PHP_INT_MIN")) {
-    \define("PHP_INT_MIN", ~PHP_INT_MAX);
-}
-
-abstract class DriverTest extends TestCase
-{
-    /**
-     * The DriverFactory to run this test on.
-     *
-     * @return callable
-     */
-    abstract public function getFactory(): callable;
-
-    /** @var Driver */
-    public $loop;
-
-    private $remainingWatchers = [];
-
-    public function setUp()
-    {
-        $this->loop = ($this->getFactory())();
-
-        if (!$this->loop instanceof Driver) {
-            $this->fail("Factory did not return a loop Driver");
-        }
-
-        // Required for error handler to work
-        Loop::set($this->loop);
-        \gc_collect_cycles();
-
-        $this->remainingWatchers = [];
-    }
-
-    public function tearDown()
-    {
-        foreach ($this->remainingWatchers as $watcher) {
-            $this->loop->cancel($watcher);
-        }
-
-        unset($this->loop);
-    }
-
-    public function start($cb): void
-    {
-        $cb($this->loop);
-        $this->loop->run();
-    }
-
-    public function testEmptyLoop(): void
-    {
-        $this->assertNull($this->loop->run());
-    }
-
-    public function testStopWorksEvenIfNotCurrentlyRunning(): void
-    {
-        $this->assertNull($this->loop->stop());
-    }
-
-    // Note: The running nesting is important for being able to continue actually still running loops (i.e. running flag set, if the driver has one) inside register_shutdown_function() for example
-    public function testLoopRunsCanBeConsecutiveAndNested(): void
-    {
-        $this->expectOutputString("123456");
-        $failingLine = 0;
-
-        $this->start(function (Driver $loop) use (&$failingLine) {
-            $loop->stop();
-            $loop->defer(function () use (&$run) {
-                echo $run = 1;
-            });
-            $loop->run();
-            if (!$run) {
-                $failingLine = __LINE__;
-            }
-            $loop->defer(function () use ($loop, &$failingLine) {
-                $loop->run();
-                echo 5;
-                $loop->defer(function () use ($loop, &$failingLine) {
-                    echo 6;
-                    $loop->stop();
-                    $this->remainingWatchers[] = $loop->defer(function () use (&$failingLine) {
-                        $failingLine = __LINE__;
-                    });
-                });
-                $loop->run();
-            });
-            $loop->defer(function () use ($loop) {
-                echo 2;
-                $loop->defer(function () {
-                    echo 4;
-                });
-            });
-            $loop->defer(function () {
-                echo 3;
-            });
-        });
-
-        $this->assertSame(0, $failingLine, "Test failed");
-    }
-
-    public function testLoopTerminatesWithOnlyUnreferencedWatchers(): void
-    {
-        $this->start(function (Driver $loop) use (&$end) {
-            $loop->unreference($this->remainingWatchers[] = $loop->onReadable(STDIN, function () {
-                // empty
-            }));
-
-            $w = $loop->delay(10000000, function () {
-                // empty
-            });
-
-            $loop->defer(function () use ($loop, $w, &$end) {
-                $loop->cancel($w);
-                $end = true;
-            });
-        });
-
-        $this->assertTrue($end);
-    }
-
-    /** This MUST NOT have a "test" prefix, otherwise it's executed as test and marked as risky. */
-    public function checkForSignalCapability(): void
-    {
-        try {
-            $watcher = $this->loop->onSignal(SIGUSR1, function () {
-            });
-            $this->loop->cancel($watcher);
-        } catch (UnsupportedFeatureException $e) {
-            $this->markTestSkipped("The loop is not capable of handling signals properly. Skipping.");
-        }
-    }
-
-    public function testWatcherUnrefRerefRunResult(): void
-    {
-        $invoked = false;
-
-        $this->start(function (Driver $loop) use (&$invoked) {
-            $watcher = $loop->defer(function () use (&$invoked) {
-                $invoked = true;
-            });
-
-            $loop->unreference($watcher);
-            $loop->unreference($watcher);
-            $loop->reference($watcher);
-        });
-
-        $this->assertTrue($invoked);
-    }
-
-    public function testDeferWatcherUnrefRunResult(): void
-    {
-        $invoked = false;
-        $watcher = null;
-        /** @var Driver|null $loop */
-        $loop = null;
-
-        $this->start(function (Driver $givenLoop) use (&$invoked, &$watcher, &$loop) {
-            $loop = $givenLoop;
-
-            $watcher = $loop->defer(function () use (&$invoked) {
-                $invoked = true;
-            });
-
-            $loop->unreference($watcher);
-        });
-
-        $this->assertFalse($invoked);
-        $loop->cancel($watcher);
-    }
-
-    public function testOnceWatcherUnrefRunResult(): void
-    {
-        $invoked = false;
-        $watcher = null;
-        /** @var Driver|null $loop */
-        $loop = null;
-
-        $this->start(function (Driver $givenLoop) use (&$invoked, &$watcher, &$loop) {
-            $loop = $givenLoop;
-
-            $watcher = $loop->delay(2000, function () use (&$invoked) {
-                $invoked = true;
-            });
-
-            $loop->unreference($watcher);
-        });
-
-        $this->assertFalse($invoked);
-        $loop->cancel($watcher);
-    }
-
-    public function testRepeatWatcherUnrefRunResult(): void
-    {
-        $invoked = false;
-        $watcher = null;
-        /** @var Driver|null $loop */
-        $loop = null;
-
-        $this->start(function (Driver $givenLoop) use (&$invoked, &$watcher, &$loop) {
-            $loop = $givenLoop;
-
-            $watcher = $loop->repeat(2000, function () use (&$invoked) {
-                $invoked = true;
-            });
-
-            $loop->unreference($watcher);
-        });
-
-        $this->assertFalse($invoked);
-        $loop->cancel($watcher);
-    }
-
-    public function testOnReadableWatcherUnrefRunResult(): void
-    {
-        $invoked = false;
-        $watcher = null;
-        /** @var Driver|null $loop */
-        $loop = null;
-
-        $this->start(function (Driver $givenLoop) use (&$invoked, &$watcher, &$loop) {
-            $loop = $givenLoop;
-
-            $watcher = $loop->onReadable(STDIN, function () use (&$invoked) {
-                $invoked = true;
-            });
-
-            $loop->unreference($watcher);
-        });
-
-        $this->assertFalse($invoked);
-        $loop->cancel($watcher);
-    }
-
-    public function testOnWritableWatcherKeepAliveRunResult(): void
-    {
-        $invoked = false;
-        $watcher = null;
-        /** @var Driver|null $loop */
-        $loop = null;
-
-        $this->start(function (Driver $givenLoop) use (&$invoked, &$watcher, &$loop) {
-            $loop = $givenLoop;
-
-            $watcher = $loop->onWritable(STDOUT, function () use (&$invoked) {
-                $invoked = true;
-            });
-
-            $loop->unreference($watcher);
-        });
-
-        $this->assertFalse($invoked);
-        $loop->cancel($watcher);
-    }
-
-    public function testOnSignalWatcherKeepAliveRunResult(): void
-    {
-        $this->checkForSignalCapability();
-
-        $invoked = false;
-
-        $this->start(function (Driver $loop) use (&$invoked) {
-            $this->remainingWatchers[] = $watcher = $loop->onSignal(SIGUSR1, function () {
-                // empty
-            });
-            $watcher = $loop->delay(100, function () use (&$invoked, $loop, $watcher) {
-                $invoked = true;
-                $loop->unreference($watcher);
-            });
-            $loop->unreference($watcher);
-        });
-        $this->assertTrue($invoked);
-    }
-
-    public function testUnreferencedDeferWatcherStillExecutes(): void
-    {
-        $invoked = false;
-        $this->start(function (Driver $loop) use (&$invoked) {
-            $watcher = $loop->defer(function () use (&$invoked) {
-                $invoked = true;
-            });
-            $loop->unreference($watcher);
-            $loop->defer(function () {
-                // just to keep loop running
-            });
-        });
-        $this->assertTrue($invoked);
-    }
-
-    public function testLoopDoesNotBlockOnNegativeTimerExpiration(): void
-    {
-        $invoked = false;
-        $this->start(function (Driver $loop) use (&$invoked) {
-            $loop->delay(1, function () use (&$invoked) {
-                $invoked = true;
-            });
-
-            \usleep(1000 * 10);
-        });
-        $this->assertTrue($invoked);
-    }
-
-    public function testDisabledDeferReenableInSubsequentTick(): void
-    {
-        $this->expectOutputString("123");
-        $this->start(function (Driver $loop) {
-            $watcherId = $loop->defer(function ($watcherId) {
-                echo 3;
-            });
-            $loop->disable($watcherId);
-            $loop->defer(function () use ($loop, $watcherId) {
-                $loop->enable($watcherId);
-                echo 2;
-            });
-            echo 1;
-        });
-    }
-
-    public function provideRegistrationArgs(): array
-    {
-        $args = [
-            ["defer", [function () {
-            }]],
-            ["delay", [5, function () {
-            }]],
-            ["repeat", [5, function () {
-            }]],
-            ["onWritable", [\STDOUT, function () {
-            }]],
-            ["onReadable", [\STDIN, function () {
-            }]],
-            ["onSignal", [\SIGUSR1, function () {
-            }]],
-        ];
-
-        return $args;
-    }
-
-    /**
-     * @requires PHP 7
-     * @dataProvider provideRegistrationArgs
-     */
-    public function testWeakTypes($type, $args): void
-    {
-        if ($type === "onSignal") {
-            $this->checkForSignalCapability();
-        }
-
-        $this->start(function (Driver $loop) use ($type, $args, &$invoked) {
-            if ($type === "onReadable") {
-                $ends = \stream_socket_pair(\stripos(PHP_OS, "win") === 0 ? STREAM_PF_INET : STREAM_PF_UNIX, STREAM_SOCK_STREAM, STREAM_IPPROTO_IP);
-                \fwrite($ends[0], "trigger readability watcher");
-                $args = [$ends[1]];
-            } else {
-                \array_pop($args);
-            }
-
-            $expectedData = 20.75;
-            if (0 === \strpos($type, "on")) {
-                $args[] = function ($watcherId, $arg, int $data) use ($loop, &$invoked, $expectedData) {
-                    $invoked = true;
-                    $this->assertSame((int) $expectedData, $data);
-                    $loop->cancel($watcherId);
-                };
-            } else {
-                $args[] = function ($watcherId, int $data) use ($loop, &$invoked, $expectedData, $type) {
-                    $invoked = true;
-                    $this->assertSame((int) $expectedData, $data);
-                    if ($type === "repeat") {
-                        $loop->cancel($watcherId);
-                    }
-                };
-            }
-            $args[] = $expectedData;
-            \call_user_func_array([$loop, $type], $args);
-
-            if ($type === "onSignal") {
-                $loop->defer(function () {
-                    \posix_kill(\getmypid(), \SIGUSR1);
-                });
-            }
-        });
-
-        $this->assertTrue($invoked);
-    }
-
-    /** @dataProvider provideRegistrationArgs */
-    public function testDisableWithConsecutiveCancel($type, $args): void
-    {
-        if ($type === "onSignal") {
-            $this->checkForSignalCapability();
-        }
-
-        $invoked = false;
-        $this->start(function (Driver $loop) use (&$invoked, $type, $args) {
-            $func = [$loop, $type];
-            $watcherId = \call_user_func_array($func, $args);
-            $loop->disable($watcherId);
-            $loop->defer(function () use (&$invoked, $loop, $watcherId) {
-                $loop->cancel($watcherId);
-                $invoked = true;
-            });
-            $this->assertFalse($invoked);
-        });
-        $this->assertTrue($invoked);
-    }
-
-    /** @dataProvider provideRegistrationArgs */
-    public function testWatcherReferenceInfo($type, $args): void
-    {
-        if ($type === "onSignal") {
-            $this->checkForSignalCapability();
-        }
-
-        $loop = $this->loop;
-
-        $func = [$loop, $type];
-        if (\substr($type, 0, 2) === "on") {
-            $type = "on_" . \lcfirst(\substr($type, 2));
-        }
-
-        // being referenced is the default
-        $watcherId1 = \call_user_func_array($func, $args);
-        $info = $loop->getInfo();
-        $expected = ["enabled" => 1, "disabled" => 0];
-        $this->assertSame($expected, $info[$type]);
-        $expected = ["referenced" => 1, "unreferenced" => 0];
-        $this->assertSame($expected, $info["enabled_watchers"]);
-
-        // explicitly reference() even though it's the default setting
-        $argsCopy = $args;
-        $watcherId2 = \call_user_func_array($func, $argsCopy);
-        $loop->reference($watcherId2);
-        $loop->reference($watcherId2);
-        $info = $loop->getInfo();
-        $expected = ["enabled" => 2, "disabled" => 0];
-        $this->assertSame($expected, $info[$type]);
-        $expected = ["referenced" => 2, "unreferenced" => 0];
-        $this->assertSame($expected, $info["enabled_watchers"]);
-
-        // disabling a referenced watcher should decrement the referenced count
-        $loop->disable($watcherId2);
-        $loop->disable($watcherId2);
-        $loop->disable($watcherId2);
-        $info = $loop->getInfo();
-        $expected = ["referenced" => 1, "unreferenced" => 0];
-        $this->assertSame($expected, $info["enabled_watchers"]);
-
-        // enabling a referenced watcher should increment the referenced count
-        $loop->enable($watcherId2);
-        $loop->enable($watcherId2);
-        $info = $loop->getInfo();
-        $expected = ["referenced" => 2, "unreferenced" => 0];
-        $this->assertSame($expected, $info["enabled_watchers"]);
-
-        // cancelling an referenced watcher should decrement the referenced count
-        $loop->cancel($watcherId2);
-        $info = $loop->getInfo();
-        $expected = ["referenced" => 1, "unreferenced" => 0];
-        $this->assertSame($expected, $info["enabled_watchers"]);
-
-        // unreference() should just increment unreferenced count
-        $watcherId2 = \call_user_func_array($func, $args);
-        $loop->unreference($watcherId2);
-        $info = $loop->getInfo();
-        $expected = ["enabled" => 2, "disabled" => 0];
-        $this->assertSame($expected, $info[$type]);
-        $expected = ["referenced" => 1, "unreferenced" => 1];
-        $this->assertSame($expected, $info["enabled_watchers"]);
-
-        $loop->cancel($watcherId1);
-        $loop->cancel($watcherId2);
-    }
-
-    /** @dataProvider provideRegistrationArgs */
-    public function testWatcherRegistrationAndCancellationInfo($type, $args): void
-    {
-        if ($type === "onSignal") {
-            $this->checkForSignalCapability();
-        }
-
-        $loop = $this->loop;
-
-        $func = [$loop, $type];
-        if (\substr($type, 0, 2) === "on") {
-            $type = "on_" . \lcfirst(\substr($type, 2));
-        }
-
-        $watcherId = \call_user_func_array($func, $args);
-        $this->assertInternalType("string", $watcherId);
-        $info = $loop->getInfo();
-        $expected = ["enabled" => 1, "disabled" => 0];
-        $this->assertSame($expected, $info[$type]);
-
-        // invoke enable() on active watcher to ensure it has no side-effects
-        $loop->enable($watcherId);
-        $info = $loop->getInfo();
-        $expected = ["enabled" => 1, "disabled" => 0];
-        $this->assertSame($expected, $info[$type]);
-
-        // invoke disable() twice to ensure it has no side-effects
-        $loop->disable($watcherId);
-        $loop->disable($watcherId);
-
-        $info = $loop->getInfo();
-        $expected = ["enabled" => 0, "disabled" => 1];
-        $this->assertSame($expected, $info[$type]);
-
-        $loop->cancel($watcherId);
-        $info = $loop->getInfo();
-        $expected = ["enabled" => 0, "disabled" => 0];
-        $this->assertSame($expected, $info[$type]);
-
-        $watcherId = \call_user_func_array($func, $args);
-        $info = $loop->getInfo();
-        $expected = ["enabled" => 1, "disabled" => 0];
-        $this->assertSame($expected, $info[$type]);
-
-        $loop->disable($watcherId);
-        $info = $loop->getInfo();
-        $expected = ["enabled" => 0, "disabled" => 1];
-        $this->assertSame($expected, $info[$type]);
-
-        $loop->enable($watcherId);
-        $info = $loop->getInfo();
-        $expected = ["enabled" => 1, "disabled" => 0];
-        $this->assertSame($expected, $info[$type]);
-
-        $loop->cancel($watcherId);
-        $info = $loop->getInfo();
-        $expected = ["enabled" => 0, "disabled" => 0];
-        $this->assertSame($expected, $info[$type]);
-
-        $loop->disable($watcherId);
-        $info = $loop->getInfo();
-        $expected = ["enabled" => 0, "disabled" => 0];
-        $this->assertSame($expected, $info[$type]);
-    }
-
-    /**
-     * @dataProvider provideRegistrationArgs
-     * @group memoryleak
-     */
-    public function testNoMemoryLeak($type, $args): void
-    {
-        if ($this->getTestResultObject()->getCollectCodeCoverageInformation()) {
-            $this->markTestSkipped("Cannot run this test with code coverage active [code coverage consumes memory which makes it impossible to rely on memory_get_usage()]");
-        }
-
-        $runs = 2000;
-
-        if ($type === "onSignal") {
-            $this->checkForSignalCapability();
-        }
-
-        $this->start(function (Driver $loop) use ($type, $args, $runs) {
-            $initialMem = \memory_get_usage();
-            $cb = function ($runs) use ($loop, $type, $args) {
-                $func = [$loop, $type];
-                for ($watchers = [], $i = 0; $i < $runs; $i++) {
-                    $watchers[] = \call_user_func_array($func, $args);
-                }
-                foreach ($watchers as $watcher) {
-                    $loop->cancel($watcher);
-                }
-                for ($watchers = [], $i = 0; $i < $runs; $i++) {
-                    $watchers[] = \call_user_func_array($func, $args);
-                }
-                foreach ($watchers as $watcher) {
-                    $loop->disable($watcher);
-                    $loop->cancel($watcher);
-                }
-                for ($watchers = [], $i = 0; $i < $runs; $i++) {
-                    $watchers[] = \call_user_func_array($func, $args);
-                }
-                if ($type === "repeat") {
-                    $loop->delay($msInterval = 7, function () use ($loop, $watchers) {
-                        foreach ($watchers as $watcher) {
-                            $loop->cancel($watcher);
-                        }
-                    });
-                } elseif ($type !== "defer" && $type !== "delay") {
-                    $loop->defer(function () use ($loop, $watchers) {
-                        foreach ($watchers as $watcher) {
-                            $loop->cancel($watcher);
-                        }
-                    });
-                }
-                $loop->run();
-                if ($type === "defer") {
-                    $loop->defer($fn = function ($watcherId, $i) use (&$fn, $loop) {
-                        if ($i) {
-                            $loop->defer($fn, --$i);
-                        }
-                    }, $runs);
-                    $loop->run();
-                }
-                if ($type === "delay") {
-                    $loop->delay($msDelay = 0, $fn = function ($watcherId, $i) use (&$fn, $loop) {
-                        if ($i) {
-                            $loop->delay($msDelay = 0, $fn, --$i);
-                        }
-                    }, $runs);
-                    $loop->run();
-                }
-                if ($type === "repeat") {
-                    $loop->repeat($msDelay = 0, $fn = function ($watcherId, $i) use (&$fn, $loop) {
-                        $loop->cancel($watcherId);
-                        if ($i) {
-                            $loop->repeat($msDelay = 0, $fn, --$i);
-                        }
-                    }, $runs);
-                    $loop->run();
-                }
-                if ($type === "onWritable") {
-                    $loop->defer(function ($watcherId, $runs) use ($loop) {
-                        $fn = function ($watcherId, $socket, $i) use (&$fn, $loop) {
-                            $loop->cancel($watcherId);
-                            if ($socket) {
-                                \fwrite($socket, ".");
-                            }
-                            if ($i) {
-                                // explicitly use *different* streams with *different* resource ids
-                                $ends = \stream_socket_pair(\stripos(PHP_OS, "win") === 0 ? STREAM_PF_INET : STREAM_PF_UNIX, STREAM_SOCK_STREAM, STREAM_IPPROTO_IP);
-                                $loop->onWritable($ends[0], $fn, --$i);
-                                $loop->onReadable($ends[1], function ($watcherId) use ($loop) {
-                                    $loop->cancel($watcherId);
-                                });
-                            }
-                        };
-                        $fn($watcherId, null, $runs);
-                    }, $runs + 1);
-                    $loop->run();
-                }
-                if ($type === "onSignal") {
-                    $sendSignal = function () {
-                        \posix_kill(\getmypid(), \SIGUSR1);
-                    };
-                    $loop->onSignal(\SIGUSR1, $fn = function ($watcherId, $signo, $i) use (&$fn, $loop, $sendSignal) {
-                        if ($i) {
-                            $loop->onSignal(\SIGUSR1, $fn, --$i);
-                            $loop->defer($sendSignal);
-                        }
-                        $loop->cancel($watcherId);
-                    }, $runs);
-                    $loop->defer($sendSignal);
-                    $loop->run();
-                }
-            };
-            $closureMem = \memory_get_usage() - $initialMem;
-            $cb($runs); /* just to set up eventual structures inside loop without counting towards memory comparison */
-            \gc_collect_cycles();
-            $initialMem = \memory_get_usage() - $closureMem;
-            $cb($runs);
-            unset($cb);
-
-            \gc_collect_cycles();
-            $endMem = \memory_get_usage();
-
-            /* this is allowing some memory usage due to runtime caches etc., but nothing actually leaking */
-            $this->assertLessThan($runs * 4, $endMem - $initialMem); // * 4, as 4 is minimal sizeof(void *)
-        });
-    }
-
-    /**
-     * The first number of each tuple indicates the tick in which the watcher is supposed to execute, the second digit
-     * indicates the order within the tick.
-     */
-    public function testExecutionOrderGuarantees(): void
-    {
-        $this->expectOutputString("01 02 03 04 " . \str_repeat("05 ", 8) . "10 11 12 " . \str_repeat("13 ", 4) . "20 " . \str_repeat("21 ", 4) . "30 40 41 ");
-        $this->start(function (Driver $loop) {
-            // Wrap in extra defer, so driver creation time doesn't count for timers, as timers are driver creation
-            // relative instead of last tick relative before first tick.
-            $loop->defer(function () use ($loop) {
-                $f = function () use ($loop) {
-                    $args = \func_get_args();
-                    return function ($watcherId) use ($loop, &$args) {
-                        if (!$args) {
-                            $this->fail("Watcher callback called too often");
-                        }
-                        $loop->cancel($watcherId);
-                        echo \array_shift($args) . \array_shift($args), " ";
-                    };
-                };
-
-                $loop->onWritable(STDOUT, $f(0, 5));
-                $writ1 = $loop->onWritable(STDOUT, $f(0, 5));
-                $writ2 = $loop->onWritable(STDOUT, $f(0, 5));
-
-                $loop->delay($msDelay = 0, $f(0, 5));
-                $del1 = $loop->delay($msDelay = 0, $f(0, 5));
-                $del2 = $loop->delay($msDelay = 0, $f(0, 5));
-                $del3 = $loop->delay($msDelay = 0, $f());
-                $del4 = $loop->delay($msDelay = 0, $f(1, 3));
-                $del5 = $loop->delay($msDelay = 0, $f(2, 0));
-                $loop->defer(function () use ($loop, $del5) {
-                    $loop->disable($del5);
-                });
-                $loop->cancel($del3);
-                $loop->disable($del1);
-                $loop->disable($del2);
-
-                $writ3 = $loop->onWritable(STDOUT, $f());
-                $loop->cancel($writ3);
-                $loop->disable($writ1);
-                $loop->disable($writ2);
-                $loop->enable($writ1);
-                $writ4 = $loop->onWritable(STDOUT, $f(1, 3));
-                $loop->onWritable(STDOUT, $f(0, 5));
-                $loop->enable($writ2);
-                $loop->disable($writ4);
-                $loop->defer(function () use ($loop, $writ4, $f) {
-                    $loop->enable($writ4);
-                    $loop->onWritable(STDOUT, $f(1, 3));
-                });
-
-                $loop->enable($del1);
-                $loop->delay($msDelay = 0, $f(0, 5));
-                $loop->enable($del2);
-                $loop->disable($del4);
-                $loop->defer(function () use ($loop, $del4, $f) {
-                    $loop->enable($del4);
-                    $loop->onWritable(STDOUT, $f(1, 3));
-                });
-
-                $loop->delay($msDelay = 1000, $f(4, 1));
-                $loop->delay($msDelay = 600, $f(3, 0));
-                $loop->delay($msDelay = 500, $f(2, 1));
-                $loop->repeat($msDelay = 500, $f(2, 1));
-                $rep1 = $loop->repeat($msDelay = 250, $f(2, 1));
-                $loop->disable($rep1);
-                $loop->delay($msDelay = 500, $f(2, 1));
-                $loop->enable($rep1);
-
-                $loop->defer($f(0, 1));
-                $def1 = $loop->defer($f(0, 3));
-                $def2 = $loop->defer($f(1, 1));
-                $def3 = $loop->defer($f());
-                $loop->defer($f(0, 2));
-                $loop->disable($def1);
-                $loop->cancel($def3);
-                $loop->enable($def1);
-                $loop->defer(function () use ($loop, $def2, $del5, $f) {
-                    $tick = $f(0, 4);
-                    $tick("invalid");
-                    $loop->defer($f(1, 0));
-                    $loop->enable($def2);
-                    $loop->defer($f(1, 2));
-                    $loop->defer(function () use ($loop, $del5, $f) {
-                        $loop->enable($del5);
-                        $loop->defer(function () use ($loop, $f) {
-                            \usleep(700000); // to have $msDelay == 500 and $msDelay == 600 run at the same tick (but not $msDelay == 150)
-                            $loop->defer(function () use ($loop, $f) {
-                                $loop->defer($f(4, 0));
-                            });
-                        });
-                    });
-                });
-                $loop->disable($def2);
-            });
-        });
-    }
-
-    public function testSignalExecutionOrder(): void
-    {
-        $this->checkForSignalCapability();
-
-        $this->expectOutputString("122222");
-        $this->start(function (Driver $loop) {
-            $f = function ($i) use ($loop) {
-                return function ($watcherId) use ($loop, $i) {
-                    $loop->cancel($watcherId);
-                    echo $i;
-                };
-            };
-
-            $loop->defer($f(1));
-            $loop->onSignal(SIGUSR1, $f(2));
-            $sig1 = $loop->onSignal(SIGUSR1, $f(2));
-            $sig2 = $loop->onSignal(SIGUSR1, $f(2));
-            $sig3 = $loop->onSignal(SIGUSR1, $f(" FAIL - MUST NOT BE CALLED "));
-            $loop->disable($sig1);
-            $loop->onSignal(SIGUSR1, $f(2));
-            $loop->disable($sig2);
-            $loop->enable($sig1);
-            $loop->cancel($sig3);
-            $loop->onSignal(SIGUSR1, $f(2));
-            $loop->defer(function () use ($loop, $sig2) {
-                $loop->enable($sig2);
-                $loop->defer(function () use ($loop) {
-                    \posix_kill(\getmypid(), \SIGUSR1);
-                    $loop->delay($msDelay = 10, function () use ($loop) {
-                        $loop->stop();
-                    });
-                });
-            });
-        });
-    }
-
-    /** @expectedException \Amp\Loop\InvalidWatcherError */
-    public function testExceptionOnEnableNonexistentWatcher(): void
-    {
-        try {
-            $this->loop->enable("nonexistentWatcher");
-        } catch (InvalidWatcherError $e) {
-            $this->assertSame("nonexistentWatcher", $e->getWatcherId());
-            throw $e;
-        }
-    }
-
-    public function testSuccessOnDisableNonexistentWatcher(): void
-    {
-        $this->loop->disable("nonexistentWatcher");
-
-        // Otherwise risky, throwing fails the test
-        $this->assertTrue(true);
-    }
-
-    public function testSuccessOnCancelNonexistentWatcher(): void
-    {
-        $this->loop->cancel("nonexistentWatcher");
-
-        // Otherwise risky, throwing fails the test
-        $this->assertTrue(true);
-    }
-
-    /** @expectedException \Amp\Loop\InvalidWatcherError */
-    public function testExceptionOnReferenceNonexistentWatcher(): void
-    {
-        try {
-            $this->loop->reference("nonexistentWatcher");
-        } catch (InvalidWatcherError $e) {
-            $this->assertSame("nonexistentWatcher", $e->getWatcherId());
-            throw $e;
-        }
-    }
-
-    public function testSuccessOnUnreferenceNonexistentWatcher(): void
-    {
-        $this->loop->unreference("nonexistentWatcher");
-
-        // Otherwise risky, throwing fails the test
-        $this->assertTrue(true);
-    }
-
-    /** @expectedException \Amp\Loop\InvalidWatcherError */
-    public function testWatcherInvalidityOnDefer(): void
-    {
-        $this->start(function (Driver $loop) {
-            $loop->defer(function ($watcher) use ($loop) {
-                $loop->enable($watcher);
-            });
-        });
-    }
-
-    /** @expectedException \Amp\Loop\InvalidWatcherError */
-    public function testWatcherInvalidityOnDelay(): void
-    {
-        $this->start(function (Driver $loop) {
-            $loop->delay($msDelay = 0, function ($watcher) use ($loop) {
-                $loop->enable($watcher);
-            });
-        });
-    }
-
-    public function testEventsNotExecutedInSameTickAsEnabled(): void
-    {
-        $this->start(function (Driver $loop) {
-            $loop->defer(function () use ($loop) {
-                $loop->defer(function () use ($loop, &$diswatchers, &$watchers) {
-                    $loop->defer(function () use ($loop, $diswatchers) {
-                        foreach ($diswatchers as $watcher) {
-                            $loop->disable($watcher);
-                        }
-                        $loop->defer(function () use ($loop, $diswatchers) {
-                            $loop->defer(function () use ($loop, $diswatchers) {
-                                foreach ($diswatchers as $watcher) {
-                                    $loop->cancel($watcher);
-                                }
-                            });
-                            foreach ($diswatchers as $watcher) {
-                                $loop->enable($watcher);
-                            }
-                        });
-                    });
-                    foreach ($watchers as $watcher) {
-                        $loop->cancel($watcher);
-                    }
-                    foreach ($diswatchers as $watcher) {
-                        $loop->disable($watcher);
-                        $loop->enable($watcher);
-                    }
-                });
-
-                $f = function () use ($loop) {
-                    $watchers[] = $loop->defer([$this, "fail"]);
-                    $watchers[] = $loop->delay($msDelay = 0, [$this, "fail"]);
-                    $watchers[] = $loop->repeat($msDelay = 0, [$this, "fail"]);
-                    $watchers[] = $loop->onWritable(STDIN, [$this, "fail"]);
-                    return $watchers;
-                };
-                $watchers = $f();
-                $diswatchers = $f();
-            });
-        });
-
-        // Otherwise risky, as we only rely on $this->fail()
-        $this->assertTrue(true);
-    }
-
-    public function testEnablingWatcherAllowsSubsequentInvocation(): void
-    {
-        $loop = $this->loop;
-        $increment = 0;
-        $watcherId = $loop->defer(function () use (&$increment) {
-            $increment++;
-        });
-        $loop->disable($watcherId);
-        $loop->delay($msDelay = 5, [$loop, "stop"]);
-        $loop->run();
-        $this->assertSame(0, $increment);
-        $loop->enable($watcherId);
-        $loop->delay($msDelay = 5, [$loop, "stop"]);
-        $loop->run();
-        $this->assertSame(1, $increment);
-    }
-
-    public function testUnresolvedEventsAreReenabledOnRunFollowingPreviousStop(): void
-    {
-        $increment = 0;
-        $this->start(function (Driver $loop) use (&$increment) {
-            $loop->defer([$loop, "stop"]);
-            $loop->run();
-
-            $loop->defer(function () use (&$increment, $loop) {
-                $loop->delay($msDelay = 100, function () use ($loop, &$increment) {
-                    $increment++;
-                    $loop->stop();
-                });
-            });
-
-            $this->assertSame(0, $increment);
-            \usleep(5000);
-        });
-        $this->assertSame(1, $increment);
-    }
-
-    public function testTimerWatcherParameterOrder(): void
-    {
-        $this->start(function (Driver $loop) {
-            $counter = 0;
-            $loop->defer(function ($watcherId) use ($loop, &$counter) {
-                $this->assertInternalType("string", $watcherId);
-                if (++$counter === 3) {
-                    $loop->stop();
-                }
-            });
-            $loop->delay($msDelay = 5, function ($watcherId) use ($loop, &$counter) {
-                $this->assertInternalType("string", $watcherId);
-                if (++$counter === 3) {
-                    $loop->stop();
-                }
-            });
-            $loop->repeat($msDelay = 5, function ($watcherId) use ($loop, &$counter) {
-                $this->assertInternalType("string", $watcherId);
-                $loop->cancel($watcherId);
-                if (++$counter === 3) {
-                    $loop->stop();
-                }
-            });
-        });
-    }
-
-    public function testStreamWatcherParameterOrder(): void
-    {
-        $this->start(function (Driver $loop) use (&$invoked) {
-            $invoked = 0;
-            $loop->onWritable(STDOUT, function ($watcherId, $stream) use ($loop, &$invoked) {
-                $this->assertInternalType("string", $watcherId);
-                $this->assertSame(STDOUT, $stream);
-                $invoked++;
-                $loop->cancel($watcherId);
-            });
-        });
-        $this->assertSame(1, $invoked);
-    }
-
-    public function testDisablingWatcherPreventsSubsequentInvocation(): void
-    {
-        $this->start(function (Driver $loop) {
-            $increment = 0;
-            $this->remainingWatchers[] = $watcherId = $loop->defer(function () use (&$increment) {
-                $increment++;
-            });
-
-            $loop->disable($watcherId);
-            $loop->delay($msDelay = 5, [$loop, "stop"]);
-
-            $this->assertSame(0, $increment);
-        });
-    }
-
-    public function testImmediateExecution(): void
-    {
-        $loop = $this->loop;
-        $increment = 0;
-        $this->start(function (Driver $loop) use (&$increment) {
-            $loop->defer(function () use (&$increment) {
-                $increment++;
-            });
-            $loop->defer([$loop, "stop"]);
-        });
-        $this->assertSame(1, $increment);
-    }
-
-    public function testImmediatelyCallbacksDoNotRecurseInSameTick(): void
-    {
-        $increment = 0;
-        $this->start(function (Driver $loop) use (&$increment) {
-            $loop->defer(function () use ($loop, &$increment) {
-                $increment++;
-                $this->remainingWatchers[] = $loop->defer(function () use (&$increment) {
-                    $increment++;
-                });
-            });
-            $loop->defer([$loop, "stop"]);
-        });
-        $this->assertSame(1, $increment);
-    }
-
-    public function testRunExecutesEventsUntilExplicitlyStopped(): void
-    {
-        $increment = 0;
-        $this->start(function (Driver $loop) use (&$increment) {
-            $loop->repeat($msInterval = 5, function ($watcherId) use ($loop, &$increment) {
-                $increment++;
-                if ($increment === 10) {
-                    $loop->cancel($watcherId);
-                }
-            });
-        });
-        $this->assertSame(10, $increment);
-    }
-
-    /**
-     * @expectedException \Exception
-     * @expectedExceptionMessage loop error
-     */
-    public function testLoopAllowsExceptionToBubbleUpDuringStart(): void
-    {
-        $this->start(function (Driver $loop) {
-            $loop->defer(function () {
-                throw new \Exception("loop error");
-            });
-        });
-    }
-
-    /**
-     * @expectedException \RuntimeException
-     * @expectedExceptionMessage test
-     */
-    public function testLoopAllowsExceptionToBubbleUpFromRepeatingAlarmDuringStart(): void
-    {
-        $this->start(function (Driver $loop) {
-            $this->remainingWatchers[] = $loop->repeat($msInterval = 1, function () {
-                throw new \RuntimeException("test");
-            });
-        });
-    }
-
-    public function testErrorHandlerCapturesUncaughtException(): void
-    {
-        $msg = "";
-        $this->loop->setErrorHandler($f = function () {
-        });
-        $oldErrorHandler = $this->loop->setErrorHandler(function (\Exception $error) use (&$msg) {
-            $msg = $error->getMessage();
-        });
-        $this->assertSame($f, $oldErrorHandler);
-        $this->start(function (Driver $loop) {
-            $loop->defer(function () {
-                throw new \Exception("loop error");
-            });
-        });
-        $this->assertSame("loop error", $msg);
-    }
-
-    /**
-     * @expectedException \RuntimeException
-     * @expectedExceptionMessage test
-     */
-    public function testLoopException(): void
-    {
-        $this->start(function (Driver $loop) {
-            $loop->defer(function () use ($loop) {
-                // force next tick, outside of primary startup tick
-                $loop->defer(function () {
-                    throw new \RuntimeException("test");
-                });
-            });
-        });
-    }
-
-    public function testOnSignalWatcher(): void
-    {
-        $this->checkForSignalCapability();
-
-        $this->expectOutputString("caught SIGUSR1");
-        $this->start(function (Driver $loop) {
-            $loop->delay($msDelay = 1, function () use ($loop) {
-                \posix_kill(\getmypid(), \SIGUSR1);
-                $loop->delay($msDelay = 10, function () use ($loop) {
-                    $loop->stop();
-                });
-            });
-
-            $loop->onSignal(SIGUSR1, function ($watcherId) use ($loop) {
-                $loop->cancel($watcherId);
-                echo "caught SIGUSR1";
-            });
-        });
-    }
-
-    public function testInitiallyDisabledOnSignalWatcher(): void
-    {
-        $this->checkForSignalCapability();
-
-        $this->expectOutputString("caught SIGUSR1");
-        $this->start(function (Driver $loop) {
-            $this->remainingWatchers[] = $stop = $loop->delay($msDelay = 100, function () use ($loop) {
-                echo "ERROR: manual stop";
-                $loop->stop();
-            });
-            $this->remainingWatchers[] = $watcherId = $loop->onSignal(SIGUSR1, function ($watcherId) use (
-                $loop,
-                $stop
-            ) {
-                echo "caught SIGUSR1";
-                $loop->disable($stop);
-                $loop->disable($watcherId);
-            });
-            $loop->disable($watcherId);
-
-            $loop->delay($msDelay = 1, function () use ($loop, $watcherId) {
-                $loop->enable($watcherId);
-                $loop->delay($msDelay = 1, function () {
-                    \posix_kill(\getmypid(), SIGUSR1);
-                });
-            });
-        });
-    }
-
-    public function testNestedLoopSignalDispatch(): void
-    {
-        $this->checkForSignalCapability();
-
-        $this->expectOutputString("inner SIGUSR2\nouter SIGUSR1\n");
-        $this->start(function (Driver $loop) {
-            $this->remainingWatchers[] = $loop->delay($msDelay = 300, function () use ($loop) {
-                $loop->stop();
-            });
-            $loop->onSignal(SIGUSR1, function ($watcherId) use ($loop) {
-                echo "outer SIGUSR1\n";
-                $loop->cancel($watcherId);
-                $loop->stop();
-            });
-
-            $loop->delay($msDelay = 1, function () {
-                /** @var Driver $loop */
-                $loop = ($this->getFactory())();
-                $stop = $loop->delay($msDelay = 100, function () use ($loop) {
-                    echo "ERROR: manual stop";
-                    $loop->stop();
-                });
-                $loop->onSignal(SIGUSR2, function ($watcherId) use ($loop, $stop) {
-                    echo "inner SIGUSR2\n";
-                    $loop->cancel($stop);
-                    $loop->cancel($watcherId);
-                });
-                $loop->delay($msDelay = 1, function () {
-                    \posix_kill(\getmypid(), SIGUSR2);
-                });
-                $loop->run();
-            });
-            $loop->delay($msDelay = 20, function () {
-                \posix_kill(\getmypid(), \SIGUSR1);
-            });
-        });
-    }
-
-    public function testCancelRemovesWatcher(): void
-    {
-        $invoked = false;
-
-        $this->start(function (Driver $loop) use (&$invoked) {
-            $watcherId = $loop->delay($msDelay = 10, function () {
-                $this->fail('Watcher was not cancelled as expected');
-            });
-
-            $loop->defer(function () use ($loop, $watcherId, &$invoked) {
-                $loop->cancel($watcherId);
-                $invoked = true;
-            });
-
-            $loop->delay($msDelay = 5, [$loop, "stop"]);
-        });
-
-        $this->assertTrue($invoked);
-    }
-
-    public function testOnWritableWatcher(): void
-    {
-        $flag = false;
-        $this->start(function (Driver $loop) use (&$flag) {
-            $loop->onWritable(STDOUT, function ($watcherId) use ($loop, &$flag) {
-                $flag = true;
-                $loop->cancel($watcherId);
-                $loop->stop();
-            });
-            $this->remainingWatchers[] = $loop->delay($msDelay = 5, [$loop, "stop"]);
-        });
-        $this->assertTrue($flag);
-    }
-
-    public function testInitiallyDisabledWriteWatcher(): void
-    {
-        $increment = 0;
-        $this->start(function (Driver $loop) {
-            $this->remainingWatchers[] = $watcherId = $loop->onWritable(STDOUT, function () use (&$increment) {
-                $increment++;
-            });
-            $loop->disable($watcherId);
-            $loop->delay($msDelay = 5, [$loop, "stop"]);
-        });
-        $this->assertSame(0, $increment);
-    }
-
-    public function testInitiallyDisabledWriteWatcherIsTriggeredOnceEnabled(): void
-    {
-        $this->expectOutputString("12");
-        $this->start(function (Driver $loop) {
-            $watcherId = $loop->onWritable(STDOUT, function ($watcherId) use ($loop) {
-                echo 2;
-                $loop->cancel($watcherId);
-                $loop->stop();
-            });
-            $loop->disable($watcherId);
-            $loop->defer(function () use ($loop, $watcherId) {
-                $loop->enable($watcherId);
-                echo 1;
-            });
-        });
-    }
-
-    /** @expectedException \RuntimeException */
-    public function testStreamWatcherDoesntSwallowExceptions(): void
-    {
-        $this->start(function (Driver $loop) {
-            $loop->onWritable(STDOUT, function ($watcherId) {
-                $this->loop->cancel($watcherId);
-                throw new \RuntimeException;
-            });
-            $this->remainingWatchers[] = $loop->delay($msDelay = 5, [$loop, "stop"]);
-        });
-    }
-
-    public function testReactorRunsUntilNoWatchersRemain(): void
-    {
-        $var1 = $var2 = 0;
-        $this->start(function (Driver $loop) use (&$var1, &$var2) {
-            $loop->repeat($msDelay = 1, function ($watcherId) use ($loop, &$var1) {
-                if (++$var1 === 3) {
-                    $loop->cancel($watcherId);
-                }
-            });
-
-            $loop->onWritable(STDOUT, function ($watcherId) use ($loop, &$var2) {
-                if (++$var2 === 4) {
-                    $loop->cancel($watcherId);
-                }
-            });
-        });
-        $this->assertSame(3, $var1);
-        $this->assertSame(4, $var2);
-    }
-
-    public function testReactorRunsUntilNoWatchersRemainWhenStartedDeferred(): void
-    {
-        $var1 = $var2 = 0;
-        $this->start(function (Driver $loop) use (&$var1, &$var2) {
-            $loop->defer(function () use ($loop, &$var1, &$var2) {
-                $loop->repeat($msDelay = 1, function ($watcherId) use ($loop, &$var1) {
-                    if (++$var1 === 3) {
-                        $loop->cancel($watcherId);
-                    }
-                });
-
-                $loop->onWritable(STDOUT, function ($watcherId) use ($loop, &$var2) {
-                    if (++$var2 === 4) {
-                        $loop->cancel($watcherId);
-                    }
-                });
-            });
-        });
-        $this->assertSame(3, $var1);
-        $this->assertSame(4, $var2);
-    }
-
-    public function testOptionalCallbackDataPassedOnInvocation(): void
-    {
-        $callbackData = new \StdClass;
-
-        $this->start(function (Driver $loop) use ($callbackData) {
-            $loop->defer(function ($watcherId, $callbackData) {
-                $callbackData->defer = true;
-            }, $callbackData);
-            $loop->delay($msDelay = 1, function ($watcherId, $callbackData) {
-                $callbackData->delay = true;
-            }, $callbackData);
-            $loop->repeat($msDelay = 1, function ($watcherId, $callbackData) use ($loop) {
-                $callbackData->repeat = true;
-                $loop->cancel($watcherId);
-            }, $callbackData);
-            $loop->onWritable(STDERR, function ($watcherId, $stream, $callbackData) use ($loop) {
-                $callbackData->onWritable = true;
-                $loop->cancel($watcherId);
-            }, $callbackData);
-        });
-
-        $this->assertTrue($callbackData->defer);
-        $this->assertTrue($callbackData->delay);
-        $this->assertTrue($callbackData->repeat);
-        $this->assertTrue($callbackData->onWritable);
-    }
-
-    public function testLoopStopPreventsTimerExecution(): void
-    {
-        $t = \microtime(1);
-        $this->start(function (Driver $loop) {
-            $this->remainingWatchers[] = $loop->delay($msDelay = 10000, function () {
-                $this->fail("Timer was executed despite stopped loop");
-            });
-            $loop->defer(function () use ($loop) {
-                $loop->stop();
-            });
-        });
-        $this->assertTrue($t + 0.1 > \microtime(1));
-    }
-
-    public function testDeferEnabledInNextTick(): void
-    {
-        $tick = function () {
-            $this->loop->defer(function () {
-                $this->loop->stop();
-            });
-            $this->loop->run();
-        };
-
-        $invoked = 0;
-
-        $this->remainingWatchers[] = $watcher = $this->loop->onWritable(STDOUT, function () use (&$invoked) {
-            $invoked++;
-        });
-
-        $tick();
-        $tick();
-        $tick();
-
-        $this->loop->disable($watcher);
-        $this->loop->enable($watcher);
-        $tick(); // disable + immediate enable after a tick should have no effect either
-
-        $this->assertSame(4, $invoked);
-    }
-
-    // getState and setState are final, but test it here again to be sure
-    public function testRegistry(): void
-    {
-        $this->assertNull($this->loop->getState("foo"));
-        $this->loop->setState("foo", NAN);
-        $this->assertNan($this->loop->getState("foo"));
-        $this->loop->setState("foo", "1");
-        $this->assertNull($this->loop->getState("bar"));
-        $this->loop->setState("baz", -INF);
-        // running must not affect state
-        $this->loop->defer([$this->loop, "stop"]);
-        $this->loop->run();
-        $this->assertSame(-INF, $this->loop->getState("baz"));
-        $this->assertSame("1", $this->loop->getState("foo"));
-    }
-
-    /** @dataProvider provideRegistryValues */
-    public function testRegistryValues($val): void
-    {
-        $this->loop->setState("foo", $val);
-        $this->assertSame($val, $this->loop->getState("foo"));
-    }
-
-    public function provideRegistryValues(): array
-    {
-        return [
-            ["string"],
-            [0],
-            [PHP_INT_MIN],
-            [-1.0],
-            [true],
-            [false],
-            [[]],
-            [null],
-            [new \StdClass],
-        ];
-    }
-
-    public function provideWatchers()
-    {
-        return [["onReadable"], ["onWritable"], ["defer"], ["delay"], ["repeat"], ["onSignal"]];
-    }
-
-    /** @dataProvider provideWatchers */
-    public function testRethrowsFromCallbacks(string $watcher): void
-    {
-        $exception = new TestException;
-
-        $awaitables = [
-            Deferred::error($exception),
-            null,
-        ];
-
-        if ($watcher === "onSignal") {
-            $this->checkForSignalCapability();
-        }
-
-        foreach ($awaitables as $awaitable) {
-            $args = [];
-
-            switch ($watcher) {
-                case "onSignal":
-                    $args[] = SIGUSR1;
-                    break;
-
-                case "onWritable":
-                    $args[] = STDOUT;
-                    break;
-
-                case "onReadable":
-                    $ends = \stream_socket_pair(\stripos(PHP_OS, "win") === 0 ? STREAM_PF_INET : STREAM_PF_UNIX, STREAM_SOCK_STREAM, STREAM_IPPROTO_IP);
-                    \fwrite($ends[0], "trigger readability watcher");
-                    $args[] = $ends[1];
-                    break;
-
-                case "delay":
-                case "repeat":
-                    $args[] = 5;
-                    break;
-            }
-
-            if ($awaitable === null) {
-                $args[] = function ($watcherId) use ($exception) {
-                    $this->loop->cancel($watcherId);
-                    throw $exception;
-                };
-            } else {
-                $args[] = function ($watcherId) use ($awaitable) {
-                    $this->loop->cancel($watcherId);
-                    return $awaitable;
-                };
-            }
-
-            \call_user_func_array([$this->loop, $watcher], $args);
-
-            if ($watcher === "onSignal") {
-                $this->loop->delay(100, function () {
-                    \posix_kill(\getmypid(), \SIGUSR1);
-                });
-            }
-
-            $this->loop->setErrorHandler($this->createCallback(1));
-            $this->loop->run();
-        }
-    }
-
-    public function testMultipleWatchersOnSameDescriptor(): void
-    {
-        $sockets = \stream_socket_pair(\stripos(PHP_OS, "win") === 0 ? STREAM_PF_INET : STREAM_PF_UNIX, STREAM_SOCK_STREAM, STREAM_IPPROTO_IP);
-        \fwrite($sockets[1], "testing");
-
-        $invoked = 0;
-        $this->remainingWatchers[] = $watcher1 = $this->loop->onReadable($sockets[0], function ($watcher) use (&$invoked
-        ) {
-            $invoked += 1;
-            $this->loop->disable($watcher);
-        });
-        $this->remainingWatchers[] = $watcher2 = $this->loop->onReadable($sockets[0], function ($watcher) use (&$invoked
-        ) {
-            $invoked += 10;
-            $this->loop->disable($watcher);
-        });
-        $this->remainingWatchers[] = $watcher3 = $this->loop->onWritable($sockets[0], function ($watcher) use (&$invoked
-        ) {
-            $invoked += 100;
-            $this->loop->disable($watcher);
-        });
-        $this->remainingWatchers[] = $watcher4 = $this->loop->onWritable($sockets[0], function ($watcher) use (&$invoked
-        ) {
-            $invoked += 1000;
-            $this->loop->disable($watcher);
-        });
-
-        $this->loop->defer(function () use ($watcher1, $watcher3) {
-            $this->loop->delay(200, function () use ($watcher1, $watcher3) {
-                $this->loop->enable($watcher1);
-                $this->loop->enable($watcher3);
-            });
-        });
-
-        $this->loop->run();
-
-        $this->assertSame(1212, $invoked);
-
-        $this->loop->enable($watcher1);
-        $this->loop->enable($watcher3);
-
-        $this->loop->delay(100, function () use ($watcher2, $watcher4) {
-            $this->loop->enable($watcher2);
-            $this->loop->enable($watcher4);
-        });
-
-        $this->loop->run();
-
-        $this->assertSame(2323, $invoked);
-    }
-
-    public function testTimerIntervalCountedWhenNotRunning(): void
-    {
-        \usleep(600000); // 600ms instead of 500ms to allow for variations in timing.
-        $start = \microtime(true);
-        $this->loop->delay(1000, function () use ($start) {
-            $this->assertLessThan(0.5, \microtime(true) - $start);
-        });
-        $this->loop->run();
-    }
-
-    public function testShortTimerDoesNotBlockOtherTimers(): void
-    {
-        $this->remainingWatchers[] = $this->loop->repeat(0, function () {
-            static $i = 0;
-
-            if (++$i === 5) {
-                $this->fail("Loop continues with repeat watcher");
-            }
-
-            \usleep(2000);
-        });
-
-        $this->loop->delay(2, function () {
-            $this->assertTrue(true);
-            $this->loop->stop();
-        });
-
-        $this->loop->run();
-    }
-
-    public function testTwoShortRepeatTimersWorkAsExpected(): void
-    {
-        $this->remainingWatchers[] = $this->loop->repeat(0, function () use (&$j) {
-            static $i = 0;
-            if (++$i === 5) {
-                $this->loop->stop();
-            }
-            $j = $i;
-        });
-        $this->remainingWatchers[] = $this->loop->repeat(0, function () use (&$k) {
-            static $i = 0;
-            if (++$i === 5) {
-                $this->loop->stop();
-            }
-            $k = $i;
-        });
-
-        $this->loop->run();
-        $this->assertLessThan(2, \abs($j - $k));
-        $this->assertNotSame(0, $j);
-    }
-
-    public function testBug163ConsecutiveDelayed(): void
-    {
-        $emits = 3;
-
-        $this->loop->defer(function () use (&$time, $emits) {
-            $time = \microtime(true);
-            for ($i = 0; $i < $emits; ++$i) {
-                delay(100);
-            }
-            $time = \microtime(true) - $time;
-        });
-
-        $this->loop->run();
-
-        $this->assertGreaterThan(100 * $emits - 2 /* 2ms grace period */, $time * 1000);
-    }
-}
diff --git a/test/Loop/EvDriverTest.php b/test/Loop/EvDriverTest.php
deleted file mode 100644
index 212ec5f..0000000
--- a/test/Loop/EvDriverTest.php
+++ /dev/null
@@ -1,28 +0,0 @@
-<?php
-
-namespace Amp\Test\Loop;
-
-use Amp\Loop\EvDriver;
-
-/**
- * @requires extension ev
- */
-class EvDriverTest extends DriverTest
-{
-    public function getFactory(): callable
-    {
-        return function () {
-            return new EvDriver;
-        };
-    }
-
-    public function testHandle()
-    {
-        $this->assertInstanceOf(\EvLoop::class, $this->loop->getHandle());
-    }
-
-    public function testSupported()
-    {
-        $this->assertTrue(EvDriver::isSupported());
-    }
-}
diff --git a/test/Loop/EventDriverTest.php b/test/Loop/EventDriverTest.php
deleted file mode 100644
index da84c5a..0000000
--- a/test/Loop/EventDriverTest.php
+++ /dev/null
@@ -1,28 +0,0 @@
-<?php
-
-namespace Amp\Test\Loop;
-
-use Amp\Loop\EventDriver;
-
-/**
- * @requires extension event
- */
-class EventDriverTest extends DriverTest
-{
-    public function getFactory(): callable
-    {
-        return function () {
-            return new EventDriver;
-        };
-    }
-
-    public function testHandle()
-    {
-        $this->assertInstanceOf(\EventBase::class, $this->loop->getHandle());
-    }
-
-    public function testSupported()
-    {
-        $this->assertTrue(EventDriver::isSupported());
-    }
-}
diff --git a/test/Loop/NativeDriverTest.php b/test/Loop/NativeDriverTest.php
deleted file mode 100644
index 6cd455b..0000000
--- a/test/Loop/NativeDriverTest.php
+++ /dev/null
@@ -1,20 +0,0 @@
-<?php
-
-namespace Amp\Test\Loop;
-
-use Amp\Loop\NativeDriver;
-
-class NativeDriverTest extends DriverTest
-{
-    public function getFactory(): callable
-    {
-        return function () {
-            return new NativeDriver;
-        };
-    }
-
-    public function testHandle(): void
-    {
-        $this->assertNull($this->loop->getHandle());
-    }
-}
diff --git a/test/Loop/UvDriverTest.php b/test/Loop/UvDriverTest.php
deleted file mode 100644
index a549423..0000000
--- a/test/Loop/UvDriverTest.php
+++ /dev/null
@@ -1,29 +0,0 @@
-<?php
-
-namespace Amp\Test\Loop;
-
-use Amp\Loop\UvDriver;
-
-/**
- * @requires extension uv
- */
-class UvDriverTest extends DriverTest
-{
-    public function getFactory(): callable
-    {
-        return function () {
-            return new UvDriver;
-        };
-    }
-
-    public function testHandle()
-    {
-        $handle = $this->loop->getHandle();
-        $this->assertTrue(\is_resource($handle) || $handle instanceof \UVLoop);
-    }
-
-    public function testSupported()
-    {
-        $this->assertTrue(UvDriver::isSupported());
-    }
-}
diff --git a/test/Loop/UvLoopDestructShutdown.phpt b/test/Loop/UvLoopDestructShutdown.phpt
deleted file mode 100644
index 2bfc2e6..0000000
--- a/test/Loop/UvLoopDestructShutdown.phpt
+++ /dev/null
@@ -1,31 +0,0 @@
---TEST--
-Test order of destruction not interfering with access to UV handles
---SKIPIF--
-<?php
-\extension_loaded("uv") or die("SKIP: ext/uv required for this test");
-?>
---FILE--
-<?php
-
-include __DIR__.'/../../vendor/autoload.php';
-
-use Amp\Loop;
-
-Loop::setState('test', new class {
-    private $handle;
-    public function __construct()
-    {
-        $this->handle = Loop::repeat(10, function () {});
-    }
-    public function __destruct()
-    {
-        Loop::cancel($this->handle);
-        print "ok";
-    }
-});
-
-Loop::delay(0, [Loop::class, "stop"]);
-
-?>
---EXPECT--
-ok
diff --git a/test/LoopTest.php b/test/LoopTest.php
deleted file mode 100644
index af8c601..0000000
--- a/test/LoopTest.php
+++ /dev/null
@@ -1,60 +0,0 @@
-<?php
-
-namespace Amp\Test;
-
-use Amp\Loop;
-use PHPUnit\Framework\TestCase;
-
-class LoopTest extends TestCase
-{
-    public function testDelayWithNegativeDelay(): void
-    {
-        $this->expectException(\Error::class);
-
-        Loop::delay(-1, function () {
-        });
-    }
-
-    public function testRepeatWithNegativeInterval(): void
-    {
-        $this->expectException(\Error::class);
-
-        Loop::repeat(-1, function () {
-        });
-    }
-
-    public function testOnReadable(): void
-    {
-        Loop::run(function () {
-            $ends = \stream_socket_pair(\stripos(PHP_OS, "win") === 0 ? STREAM_PF_INET : STREAM_PF_UNIX, STREAM_SOCK_STREAM, STREAM_IPPROTO_IP);
-            \fwrite($ends[0], "trigger readability watcher");
-
-            Loop::onReadable($ends[1], function ($watcherId) {
-                $this->assertTrue(true);
-                Loop::cancel($watcherId);
-                Loop::stop();
-            });
-        });
-    }
-
-    public function testOnWritable(): void
-    {
-        Loop::run(function () {
-            Loop::onWritable(STDOUT, function ($watcherId) {
-                $this->assertTrue(true);
-                Loop::cancel($watcherId);
-                Loop::stop();
-            });
-        });
-    }
-
-    public function testGet(): void
-    {
-        $this->assertInstanceOf(Loop\Driver::class, Loop::get());
-    }
-
-    public function testGetInto(): void
-    {
-        $this->assertSame(Loop::get()->getInfo(), Loop::getInfo());
-    }
-}
diff --git a/test/RethrowTest.php b/test/RethrowTest.php
deleted file mode 100644
index 3724288..0000000
--- a/test/RethrowTest.php
+++ /dev/null
@@ -1,23 +0,0 @@
-<?php
-
-namespace Amp\Test;
-
-use Amp\Loop;
-use Amp\PHPUnit\TestCase;
-use Amp\PHPUnit\TestException;
-use Concurrent\Deferred;
-use function Amp\delay;
-use function Amp\rethrow;
-
-class RethrowTest extends TestCase
-{
-    public function testRethrow(): void
-    {
-        $exception = new TestException;
-
-        Loop::setErrorHandler($this->createCallback(1));
-
-        rethrow(Deferred::error($exception));
-        delay(1);
-    }
-}
diff --git a/test/StructTest.php b/test/StructTest.php
index 3575585..073a349 100644
--- a/test/StructTest.php
+++ b/test/StructTest.php
@@ -2,6 +2,8 @@
 
 namespace Amp\Test;
 
+use PHPUnit\Framework\TestCase;
+
 class StructTestFixture
 {
     use \Amp\Struct;
@@ -9,11 +11,11 @@ class StructTestFixture
     public $_foofoofoofoofoofoofoofoobar;
 }
 
-class StructTest extends \PHPUnit\Framework\TestCase
+class StructTest extends TestCase
 {
     /**
      * @expectedException \Error
-     * @expectedExceptionMessage Amp\Test\StructTestFixture property "callbac" does not exist ... did you mean
+     * @expectedExceptionMessage Amp\Test\StructTestFixture property 'callbac' does not exist ... did you mean
      *     "callback?"
      */
     public function testSetErrorWithSuggestion(): void
@@ -25,7 +27,7 @@ class StructTest extends \PHPUnit\Framework\TestCase
 
     /**
      * @expectedException \Error
-     * @expectedExceptionMessage Amp\Test\StructTestFixture property "callbac" does not exist ... did you mean
+     * @expectedExceptionMessage Amp\Test\StructTestFixture property 'callbac' does not exist ... did you mean
      *     "callback?"
      */
     public function testGetErrorWithSuggestion(): void
@@ -36,7 +38,7 @@ class StructTest extends \PHPUnit\Framework\TestCase
 
     /**
      * @expectedException \Error
-     * @expectedExceptionMessage Amp\Test\StructTestFixture property "callZZZZZZZZZZZ" does not exist
+     * @expectedExceptionMessage Amp\Test\StructTestFixture property 'callZZZZZZZZZZZ' does not exist
      */
     public function testSetErrorWithoutSuggestion(): void
     {
@@ -46,7 +48,7 @@ class StructTest extends \PHPUnit\Framework\TestCase
 
     /**
      * @expectedException \Error
-     * @expectedExceptionMessage Amp\Test\StructTestFixture property "callZZZZZZZZZZZ" does not exist
+     * @expectedExceptionMessage Amp\Test\StructTestFixture property 'callZZZZZZZZZZZ' does not exist
      */
     public function testGetErrorWithoutSuggestion(): void
     {
@@ -56,7 +58,7 @@ class StructTest extends \PHPUnit\Framework\TestCase
 
     /**
      * @expectedException \Error
-     * @expectedExceptionMessage Amp\Test\StructTestFixture property "__propertySuggestThreshold" does not exist
+     * @expectedExceptionMessage Amp\Test\StructTestFixture property '__propertySuggestThreshold' does not exist
      */
     public function testSuggestionIgnoresPropertyStartingWithUnderscore(): void
     {
@@ -68,7 +70,7 @@ class StructTest extends \PHPUnit\Framework\TestCase
     {
         // Use regexp to ensure no property is suggested, because expected message is a prefix then and still passes
         $this->expectException(\Error::class);
-        $this->expectExceptionMessageRegExp("(Amp\\\\Test\\\\StructTestFixture property \"foofoofoofoofoofoofoofoobar\" does not exist$)");
+        $this->expectExceptionMessageRegExp("(Amp\\\\Test\\\\StructTestFixture property 'foofoofoofoofoofoofoofoobar' does not exist$)");
 
         $struct = new StructTestFixture;
         $struct->foofoofoofoofoofoofoofoobar = "test";
@@ -78,7 +80,7 @@ class StructTest extends \PHPUnit\Framework\TestCase
     {
         // Use regexp to ensure no property is suggested, because expected message is a prefix then and still passes
         $this->expectException(\Error::class);
-        $this->expectExceptionMessageRegExp("(Amp\\\\Test\\\\StructTestFixture property \"foofoofoofoofoofoofoofoobar\" does not exist$)");
+        $this->expectExceptionMessageRegExp("(Amp\\\\Test\\\\StructTestFixture property 'foofoofoofoofoofoofoofoobar' does not exist$)");
 
         $struct = new StructTestFixture;
         $struct->foofoofoofoofoofoofoofoobar;
diff --git a/test/TaskTest.php b/test/TaskTest.php
index 45717f9..d5723b6 100644
--- a/test/TaskTest.php
+++ b/test/TaskTest.php
@@ -2,11 +2,11 @@
 
 namespace Amp\Test;
 
-use Amp\PHPUnit\TestCase;
+use Concurrent\AsyncTestCase;
 use Concurrent\Task;
 use function Amp\delay;
 
-class TaskTest extends TestCase
+class TaskTest extends AsyncTestCase
 {
     public function testSequentialAwait(): void
     {
diff --git a/test/TimeoutTest.php b/test/TimeoutTest.php
index 5c4e0cb..06ec567 100644
--- a/test/TimeoutTest.php
+++ b/test/TimeoutTest.php
@@ -3,37 +3,34 @@
 namespace Amp\Test;
 
 use Amp\TimeoutException;
+use Concurrent\AsyncTestCase;
 use Concurrent\Deferred;
 use Concurrent\Task;
-use PHPUnit\Framework\TestCase;
 use function Amp\delay;
 use function Amp\timeout;
 
-class TimeoutTest extends TestCase
+class TimeoutTest extends AsyncTestCase
 {
-    public function testSuccessfulPromise(): void
+    public function testSuccessful(): void
     {
         $value = 1;
 
-        $awaitable = Deferred::value($value);
-        $awaitable = timeout($awaitable, 100);
-
-        $this->assertSame($value, Task::await($awaitable));
+        $this->assertSame($value, timeout(Deferred::value($value), 100));
     }
 
-    public function testFailedPromise(): void
+    public function testFailure(): void
     {
         $exception = new \Exception;
 
         $awaitable = Deferred::error($exception);
-        $awaitable = timeout($awaitable, 100);
 
         $this->expectExceptionObject($exception);
-        Task::await($awaitable);
+
+        timeout($awaitable, 100);
     }
 
     /**
-     * @depends testSuccessfulPromise
+     * @depends testSuccessful
      */
     public function testFastPending(): void
     {
@@ -45,11 +42,11 @@ class TimeoutTest extends TestCase
             return $value;
         });
 
-        $this->assertSame($value, Task::await(timeout($awaitable, 100)));
+        $this->assertSame($value, timeout($awaitable, 100));
     }
 
     /**
-     * @depends testSuccessfulPromise
+     * @depends testSuccessful
      */
     public function testSlowPending(): void
     {
@@ -64,7 +61,7 @@ class TimeoutTest extends TestCase
         $this->expectException(TimeoutException::class);
 
         try {
-            Task::await(timeout($awaitable, 100));
+            timeout($awaitable, 100);
         } finally {
             Task::await($awaitable); // await to clear pending watchers
         }