Improve mocking support

Plugin.php

@@ -12,5 +12,6 @@ class Plugin implements PluginEntryPointInterface
     {
     	$psalm->addStubFile(__DIR__ . '/stubs/Assert.php');
         $psalm->addStubFile(__DIR__ . '/stubs/TestCase.php');
+        $psalm->addStubFile(__DIR__ . '/stubs/MockBuilder.php');
     }
 }

stubs/MockBuilder.php

@@ -0,0 +1,33 @@
+<?php
+namespace PHPUnit\Framework\MockObject;
+
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @template T
+ */
+class MockBuilder
+{
+    /**
+     * @template-typeof T $type
+     * @param TestCase     $testCase
+     * @param class-string $type
+     */
+    public function __construct(TestCase $testCase, $type) {}
+
+    /**
+     * Creates a mock object using a fluent interface.
+     *
+     * @return MockObject&T
+     */
+    public function getMock() {}
+
+    /**
+     * Specifies the subset of methods to mock. Default is to mock none of them.
+     *
+     * @param array|null $methods
+     *
+     * @return static
+     */
+    public function setMethods(array $methods = null) {}
+}

stubs/TestCase.php

@@ -1,8 +1,8 @@
 <?php
-
 namespace PHPUnit\Framework;
 
 use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\MockObject\MockBuilder;
 
 abstract class TestCase extends Assert implements Test, SelfDescribing
 {
@@ -13,4 +13,15 @@ abstract class TestCase extends Assert implements Test, SelfDescribing
      * @return MockObject&T
      */
     public function createMock($class) {}
-}
+
+    /**
+     * Returns a builder object to create mock objects using a fluent interface.
+     *
+     * @template T
+     * @template-typeof T $className
+     * @param class-string $className
+     *
+     * @return MockBuilder<T>
+     */
+    public function getMockBuilder(string $className) {}
+}