Refactor Registry into a trait, so it can be tested separately

phpunit.xml

@@ -0,0 +1,12 @@
+<phpunit bootstrap="./vendor/autoload.php" colors="true">
+    <testsuites>
+        <testsuite name="Tests">
+            <directory>./test</directory>
+        </testsuite>
+    </testsuites>
+    <filter>
+        <whitelist addUncoveredFilesFromWhitelist="true">
+            <directory>./src</directory>
+        </whitelist>
+    </filter>
+</phpunit>

src/Loop.php

@@ -4,16 +4,13 @@ namespace Interop\Async;
 
 final class Loop
 {
+    use Registry;
+
     /**
      * @var LoopDriver
      */
     private static $driver = null;
 
-    /**
-     * @var array
-     */
-    private static $registry = [];
-
     /**
      * Execute a callback within the scope of an event loop driver.
      *
@@ -64,49 +61,6 @@ final class Loop
         self::get()->stop();
     }
 
-    /**
-     * Stores information in the loop bound registry. This can be used to store
-     * loop bound information. Stored information is package private.
-     * Packages MUST NOT retrieve the stored state of other packages.
-     *
-     * Therefore packages SHOULD use the following prefix to keys:
-     * `vendor.package.`
-     *
-     * @param string $key namespaced storage key
-     * @param mixed $value the value to be stored
-     *
-     * @return void
-     */
-    public static function storeState($key, $value)
-    {
-        if (self::$driver === null) {
-            throw new \RuntimeException('Not within the scope of an event loop driver');
-        }
-
-        self::$registry[$key] = $value;
-    }
-
-    /**
-     * Fetches information stored bound to the loop. Stored information is
-     * package private. Packages MUST NOT retrieve the stored state of
-     * other packages.
-     *
-     * Therefore packages SHOULD use the following prefix to keys:
-     * `vendor.package.`
-     *
-     * @param string $key namespaced storage key
-     *
-     * @return mixed previously stored value or null if it doesn't exist
-     */
-    public static function fetchState($key)
-    {
-        if (self::$driver === null) {
-            throw new \RuntimeException('Not within the scope of an event loop driver');
-        }
-
-        return isset(self::$registry[$key]) ? self::$registry[$key] : null;
-    }
-
     /**
      * Defer the execution of a callback.
      *

src/Registry.php

@@ -0,0 +1,57 @@
+<?php
+
+namespace Interop\Async\EventLoop;
+
+trait Registry {
+    /**
+     * @var array
+     */
+    private static $registry = null;
+
+    /**
+     * Stores information in the loop bound registry. This can be used to store
+     * loop bound information. Stored information is package private.
+     * Packages MUST NOT retrieve the stored state of other packages.
+     *
+     * Therefore packages SHOULD use the following prefix to keys:
+     * `vendor.package.`
+     *
+     * @param string $key namespaced storage key
+     * @param mixed $value the value to be stored
+     *
+     * @return void
+     */
+    public static function storeState($key, $value)
+    {
+        if (self::$registry === null) {
+            throw new \RuntimeException('Not within the scope of an event loop driver');
+        }
+
+        if ($value === null) {
+            unset(self::$registry[$key]);
+        } else {
+            self::$registry[$key] = $value;
+        }
+    }
+
+    /**
+     * Fetches information stored bound to the loop. Stored information is
+     * package private. Packages MUST NOT retrieve the stored state of
+     * other packages.
+     *
+     * Therefore packages SHOULD use the following prefix to keys:
+     * `vendor.package.`
+     *
+     * @param string $key namespaced storage key
+     *
+     * @return mixed previously stored value or null if it doesn't exist
+     */
+    public static function fetchState($key)
+    {
+        if (self::$registry === null) {
+            throw new \RuntimeException('Not within the scope of an event loop driver');
+        }
+
+        return isset(self::$registry[$key]) ? self::$registry[$key] : null;
+    }
+}

test/RegistryTest.php

@@ -0,0 +1,60 @@
+<?php
+
+namespace Interop\Async\EventLoop;
+
+class RegistryTest extends \PHPUnit_Framework_TestCase {
+    use Registry;
+
+    protected function setUp() {
+        self::$registry = null;
+    }
+
+    /**
+     * @test
+     * @expectedException \RuntimeException
+     */
+    public function fetchfailsOutsideOfLoop() {
+        self::fetchState("foobar");
+    }
+
+    /**
+     * @test
+     * @expectedException \RuntimeException
+     */
+    public function storefailsOutsideOfLoop() {
+        self::fetchState("store");
+    }
+
+    /** @test */
+    public function defaultsToNull() {
+        // emulate we're in an event loop…
+        self::$registry = [];
+        $this->assertNull(self::fetchState("foobar"));
+    }
+
+    /**
+     * @test
+     * @dataProvider provideValues
+     */
+    public function fetchesStoredValue($value) {
+        // emulate we're in an event loop…
+        self::$registry = [];
+
+        $this->assertNull(self::fetchState("foobar"));
+        self::storeState("foobar", $value);
+
+        $this->assertSame($value, self::fetchState("foobar"));
+    }
+
+    public function provideValues() {
+        return [
+            ["string"],
+            [42],
+            [1.001],
+            [true],
+            [false],
+            [null],
+            [new \StdClass],
+        ];
+    }
+}