Mockito \#1013: Defines and implements API for static mocking.

src/main/java/org/mockito/Captor.java

@@ -15,9 +15,16 @@
  *
  *    @Captor ArgumentCaptor<AsyncCallback<Foo>> captor;
  *
+ *    private AutoCloseable closeable;
+ *
  *    @Before
- *    public void init(){
- *       MockitoAnnotations.initMocks(this);
+ *    public void open() {
+ *       MockitoAnnotations.openMocks(this);
+ *    }
+ *
+ *    @After
+ *    public void release() throws Exception {
+ *       closeable.close();
  *    }
  *
  *    @Test public void shouldDoSomethingUseful() {

src/main/java/org/mockito/InjectMocks.java

@@ -71,8 +71,14 @@
  *
  *   public class SampleBaseTestCase {
  *
- *       @Before public void initMocks() {
- *           MockitoAnnotations.initMocks(this);
+ *       private AutoCloseable closeable;
+ *
+ *       @Before public void openMocks() {
+ *           closeable = MockitoAnnotations.openMocks(this);
+ *       }
+ *
+ *       @After public void releaseMocks() throws Exception {
+ *           closeable.close();
  *       }
  *   }
  * </code></pre>
@@ -141,11 +147,11 @@
  * </p>
  *
  * <p>
- * <strong><code>MockitoAnnotations.initMocks(this)</code></strong> method has to be called to initialize annotated objects.
- * In above example, <code>initMocks()</code> is called in &#064;Before (JUnit4) method of test's base class.
- * For JUnit3 <code>initMocks()</code> can go to <code>setup()</code> method of a base class.
- * <strong>Instead</strong> you can also put initMocks() in your JUnit runner (&#064;RunWith) or use the built-in
- * {@link MockitoJUnitRunner}.
+ * <strong><code>MockitoAnnotations.openMocks(this)</code></strong> method has to be called to initialize annotated objects.
+ * In above example, <code>openMocks()</code> is called in &#064;Before (JUnit4) method of test's base class.
+ * For JUnit3 <code>openMocks()</code> can go to <code>setup()</code> method of a base class.
+ * <strong>Instead</strong> you can also put openMocks() in your JUnit runner (&#064;RunWith) or use the built-in
+ * {@link MockitoJUnitRunner}. Also, make sure to release any mocks after disposing your test class with a corresponding hook.
  * </p>
  *
  * <p>
@@ -155,7 +161,7 @@
  *
  * @see Mock
  * @see Spy
- * @see MockitoAnnotations#initMocks(Object)
+ * @see MockitoAnnotations#openMocks(Object)
  * @see MockitoJUnitRunner
  * @since 1.8.3
  */

src/main/java/org/mockito/Mock.java

@@ -23,6 +23,7 @@
  * <li>Minimizes repetitive mock creation code.</li>
  * <li>Makes the test class more readable.</li>
  * <li>Makes the verification error easier to read because the <b>field name</b> is used to identify the mock.</li>
+ * <li>Automatically detects static mocks of type {@link MockedStatic} and infers the static mock type of the type parameter.</li>
  * </ul>
  *
  * <pre class="code"><code class="java">
@@ -43,24 +44,30 @@
  *
  *   public class SampleBaseTestCase {
  *
- *       &#064;Before public void initMocks() {
- *           MockitoAnnotations.initMocks(this);
+ *       private AutoCloseable closeable;
+ *
+ *       &#064;Before public void openMocks() {
+ *           closeable = MockitoAnnotations.openMocks(this);
+ *       }
+ *
+ *       &#064;After public void releaseMocks() throws Exception {
+ *           closeable.close();
  *       }
  *   }
  * </code></pre>
  *
  * <p>
- * <strong><code>MockitoAnnotations.initMocks(this)</code></strong> method has to be called to initialize annotated objects.
- * In above example, <code>initMocks()</code> is called in &#064;Before (JUnit4) method of test's base class.
- * For JUnit3 <code>initMocks()</code> can go to <code>setup()</code> method of a base class.
- * <strong>Instead</strong> you can also put initMocks() in your JUnit runner (&#064;RunWith) or use the built-in
- * {@link MockitoJUnitRunner}.
+ * <strong><code>MockitoAnnotations.openMocks(this)</code></strong> method has to be called to initialize annotated objects.
+ * In above example, <code>openMocks()</code> is called in &#064;Before (JUnit4) method of test's base class.
+ * For JUnit3 <code>openMocks()</code> can go to <code>setup()</code> method of a base class.
+ * <strong>Instead</strong> you can also put openMocks() in your JUnit runner (&#064;RunWith) or use the built-in
+ * {@link MockitoJUnitRunner}. Also, make sure to release any mocks after disposing your test class with a corresponding hook.
  * </p>
  *
  * @see Mockito#mock(Class)
  * @see Spy
  * @see InjectMocks
- * @see MockitoAnnotations#initMocks(Object)
+ * @see MockitoAnnotations#openMocks(Object)
  * @see MockitoJUnitRunner
  */
 @Target({FIELD, PARAMETER})

src/main/java/org/mockito/MockSettings.java

@@ -340,6 +340,21 @@ public interface MockSettings extends Serializable {
     @Incubating
     <T> MockCreationSettings<T> build(Class<T> typeToMock);
 
+    /**
+     * Creates immutable view of mock settings used later by Mockito, for use within a static mocking.
+     * Framework integrators can use this method to create instances of creation settings
+     * and use them in advanced use cases, for example to create invocations with {@link InvocationFactory},
+     * or to implement custom {@link MockHandler}.
+     * Since {@link MockCreationSettings} is {@link NotExtensible}, Mockito public API needs a creation method for this type.
+     *
+     * @param classToMock class to mock
+     * @param <T> type to mock
+     * @return immutable view of mock settings
+     * @since 2.10.0
+     */
+    @Incubating
+    <T> MockCreationSettings<T> buildStatic(Class<T> classToMock);
+
     /**
      * Lenient mocks bypass "strict stubbing" validation (see {@link Strictness#STRICT_STUBS}).
      * When mock is declared as lenient none of its stubbings will be checked for potential stubbing problems such as

src/main/java/org/mockito/MockedStatic.java

@@ -0,0 +1,79 @@
+/*
+ * Copyright (c) 2007 Mockito contributors
+ * This program is made available under the terms of the MIT License.
+ */
+package org.mockito;
+
+import org.mockito.stubbing.OngoingStubbing;
+import org.mockito.verification.VerificationMode;
+
+import static org.mockito.Mockito.*;
+
+/**
+ * Represents an active mock of a type's static methods. The mocking only affects the thread
+ * on which this static mock was created and it is not safe to use this object from another
+ * thread. The static mock is released when this object's {@link MockedStatic#close()} method
+ * is invoked. If this object is never closed, the static mock will remain active on the
+ * initiating thread. It is therefore recommended to create this object within a try-with-resources
+ * statement unless when managed explicitly, for example by using a JUnit rule or extension.
+ * <p>
+ * If the {@link Mock} annotation is used on fields or method parameters of this type, a static mock
+ * is created instead of a regular mock. The static mock is activated and released upon completing any
+ * relevant test.
+ *
+ * @param <T> The type being mocked.
+ */
+@Incubating
+public interface MockedStatic<T> extends AutoCloseable {
+
+    /**
+     * See {@link Mockito#when(Object)}.
+     */
+    <S> OngoingStubbing<S> when(Verification verification);
+
+    /**
+     * See {@link Mockito#verify(Object)}.
+     */
+    default void verify(Verification verification) {
+        verify(times(1), verification);
+    }
+
+    /**
+     * See {@link Mockito#verify(Object, VerificationMode)}.
+     */
+    void verify(VerificationMode mode, Verification verification);
+
+    /**
+     * See {@link Mockito#reset(Object[])}.
+     */
+    void reset();
+
+    /**
+     * See {@link Mockito#clearInvocations(Object[])}.
+     */
+    void clearInvocations();
+
+    /**
+     * {@link Mockito#verifyNoMoreInteractions(Object...)}.
+     */
+    void verifyNoMoreInteractions();
+
+    /**
+     * See {@link Mockito#verifyNoInteractions(Object...)}.
+     */
+    void verifyNoInteractions();
+
+    @Override
+    void close();
+
+    /**
+     * Releases this static mock and is non-operational if already released.
+     */
+    void closeOnDemand();
+
+    @FunctionalInterface
+    interface Verification {
+
+        void apply() throws Throwable;
+    }
+}

src/main/java/org/mockito/Mockito.java

@@ -105,6 +105,7 @@
  *      <a href="#45">45. New JUnit Jupiter (JUnit5+) extension</a><br/>
  *      <a href="#46">46. New <code>Mockito.lenient()</code> and <code>MockSettings.lenient()</code> methods (Since 2.20.0)</a><br/>
  *      <a href="#47">47. New API for clearing mock state in inline mocking (Since 2.25.0)</a><br/>
+ *      <a href="#48">48. New API for mocking static methods (Since 3.4.0)</a><br/>
  * </b>
  *
  * <h3 id="0">0. <a class="meaningful_link" href="#mockito2" name="mockito2">Migrating to Mockito 2</a></h3>
@@ -461,7 +462,7 @@
  * runner:
  *
  * <pre class="code"><code class="java">
- * MockitoAnnotations.initMocks(testClass);
+ * MockitoAnnotations.openMocks(testClass);
  * </code></pre>
  *
  * You can use built-in runner: {@link MockitoJUnitRunner} or a rule: {@link MockitoRule}.
@@ -863,7 +864,7 @@
  * should only use partial mocks as a last resort. See point 16 about partial mocks.
  *
  * <p>
- * All new annotations are <b>*only*</b> processed on {@link MockitoAnnotations#initMocks(Object)}.
+ * All new annotations are <b>*only*</b> processed on {@link MockitoAnnotations#openMocks(Object)}.
  * Just like for &#064;{@link Mock} annotation you can use the built-in runner: {@link MockitoJUnitRunner} or rule:
  * {@link MockitoRule}.
  * <p>
@@ -907,7 +908,7 @@
  * Mockito will now try to instantiate &#064;{@link Spy} and will instantiate &#064;{@link InjectMocks} fields
  * using <b>constructor</b> injection, <b>setter</b> injection, or <b>field</b> injection.
  * <p>
- * To take advantage of this feature you need to use {@link MockitoAnnotations#initMocks(Object)}, {@link MockitoJUnitRunner}
+ * To take advantage of this feature you need to use {@link MockitoAnnotations#openMocks(Object)}, {@link MockitoJUnitRunner}
  * or {@link MockitoRule}.
  * <p>
  * Read more about available tricks and the rules of injection in the javadoc for {@link InjectMocks}
@@ -1144,7 +1145,7 @@
  *
  * <ul>
  *     <li>Annotating the JUnit test class with a <code>&#064;{@link org.junit.runner.RunWith}({@link MockitoJUnitRunner}.class)</code></li>
- *     <li>Invoking <code>{@link MockitoAnnotations#initMocks(Object)}</code> in the <code>&#064;{@link org.junit.Before}</code> method</li>
+ *     <li>Invoking <code>{@link MockitoAnnotations#openMocks(Object)}</code> in the <code>&#064;{@link org.junit.Before}</code> method</li>
  * </ul>
  *
  * Now you can choose to use a rule :
@@ -1541,6 +1542,29 @@
  * Hence, we introduced a new API to explicitly clear mock state (only make sense in inline mocking!).
  * See example usage in {@link MockitoFramework#clearInlineMocks()}.
  * If you have feedback or a better idea how to solve the problem please reach out.
+ *
+ *
+ * <h3 id="48">48. <a class="meaningful_link" href="#static_mocks" name="static_mocks">Mocking static methods</a> (since 3.4.0)</h3>
+ *
+ * When using the <a href="#0.2">inline mock maker</a>, it is possible to mock static method invocations within the current
+ * thread and a user-defined scope. This way, Mockito assures that concurrently and sequentially running tests do not interfere.
+ *
+ * To make sure a static mock remains temporary, it is recommended to define the scope within a try-with-resources construct.
+ * In the following example, the <code>Foo</code> type's static method would return <code>foo</code> unless mocked:
+ *
+ * <pre class="code"><code class="java">
+ * assertEquals("foo", Foo.method());
+ * try (MockedStatic<Foo> mocked = mockStatic(Foo.class)) {
+ * mocked.when(Foo::method).thenReturn("bar");
+ * assertEquals("bar", Foo.method());
+ * mocked.verify(Foo::method);
+ * }
+ * assertEquals("foo", Foo.method());
+ * </code></pre>
+ *
+ * Due to the defined scope of the static mock, it returns to its original behvior once the scope is released. To define mock
+ * behavior and to verify static method invocations, use the <code>MockedStatic</code> that is returned.
+ * <p>
  */
 @SuppressWarnings("unchecked")
 public class Mockito extends ArgumentMatchers {
@@ -2026,6 +2050,73 @@ public static <T> T spy(Class<T> classToSpy) {
                 classToSpy, withSettings().useConstructor().defaultAnswer(CALLS_REAL_METHODS));
     }
 
+    /**
+     * Creates a thread-local mock controller for all static methods of the given class or interface.
+     * The returned object's {@link MockedStatic#close()} method must be called upon completing the
+     * test or the mock will remain active on the current thread.
+     * <p>
+     * See examples in javadoc for {@link Mockito} class
+     *
+     * @param classToMock class or interface of which static mocks should be mocked.
+     * @return mock controller
+     */
+    @Incubating
+    @CheckReturnValue
+    public static <T> MockedStatic<T> mockStatic(Class<T> classToMock) {
+        return mockStatic(classToMock, withSettings());
+    }
+
+    /**
+     * Creates a thread-local mock controller for all static methods of the given class or interface.
+     * The returned object's {@link MockedStatic#close()} method must be called upon completing the
+     * test or the mock will remain active on the current thread.
+     * <p>
+     * See examples in javadoc for {@link Mockito} class
+     *
+     * @param classToMock class or interface of which static mocks should be mocked.
+     * @param defaultAnswer the default answer when invoking static methods.
+     * @return mock controller
+     */
+    @Incubating
+    @CheckReturnValue
+    public static <T> MockedStatic<T> mockStatic(Class<T> classToMock, Answer defaultAnswer) {
+        return mockStatic(classToMock, withSettings().defaultAnswer(defaultAnswer));
+    }
+
+    /**
+     * Creates a thread-local mock controller for all static methods of the given class or interface.
+     * The returned object's {@link MockedStatic#close()} method must be called upon completing the
+     * test or the mock will remain active on the current thread.
+     * <p>
+     * See examples in javadoc for {@link Mockito} class
+     *
+     * @param classToMock class or interface of which static mocks should be mocked.
+     * @param name the name of the mock to use in error messages.
+     * @return mock controller
+     */
+    @Incubating
+    @CheckReturnValue
+    public static <T> MockedStatic<T> mockStatic(Class<T> classToMock, String name) {
+        return mockStatic(classToMock, withSettings().name(name));
+    }
+
+    /**
+     * Creates a thread-local mock controller for all static methods of the given class or interface.
+     * The returned object's {@link MockedStatic#close()} method must be called upon completing the
+     * test or the mock will remain active on the current thread.
+     * <p>
+     * See examples in javadoc for {@link Mockito} class
+     *
+     * @param classToMock class or interface of which static mocks should be mocked.
+     * @param mockSettings the settings to use where only name and default answer are considered.
+     * @return mock controller
+     */
+    @Incubating
+    @CheckReturnValue
+    public static <T> MockedStatic<T> mockStatic(Class<T> classToMock, MockSettings mockSettings) {
+        return MOCKITO_CORE.mockStatic(classToMock, mockSettings);
+    }
+
     /**
      * Enables stubbing methods. Use it when you want the mock to return particular value when particular method is called.
      * <p>