Add ErrorProne MockitoInternalUsage checker

subprojects/errorprone/src/main/java/org/mockito/errorprone/bugpatterns/MockitoInternalUsage.java

@@ -0,0 +1,56 @@
+/*
+ * Copyright (c) 2017 Mockito contributors
+ * This program is made available under the terms of the MIT License.
+ */
+package org.mockito.errorprone.bugpatterns;
+
+import static com.google.errorprone.matchers.Matchers.packageStartsWith;
+
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.BugPattern.ProvidesFix;
+import com.google.errorprone.BugPattern.SeverityLevel;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MemberSelectTreeMatcher;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.google.errorprone.util.ASTHelpers;
+import com.sun.source.tree.MemberSelectTree;
+import com.sun.source.tree.Tree;
+import com.sun.tools.javac.code.Symbol;
+
+/**
+ * {@link com.google.errorprone.bugpatterns.BugChecker} that detects usages of
+ * org.mockito.internal.*
+ */
+@BugPattern(
+    name = "MockitoInternalUsage",
+    summary = "org.mockito.internal.* is a private API and should not be used by clients",
+    explanation =
+        "Classes under `org.mockito.internal.*` are internal implementation details and are"
+            + " not part of Mockito's public API. Mockito team does not support them, and they"
+            + " may change at any time. Depending on them may break your code when you upgrade"
+            + " to new versions of Mockito."
+            + "This checker ensures that your code will not break with future Mockito upgrades."
+            + "Mockito's public API is documented at"
+            + " https://www.javadoc.io/doc/org.mockito/mockito-core/. If you believe that there"
+            + " is no replacement available in the public API for your use-case, contact the"
+            + " Mockito team at https://github.com/mockito/mockito/issues.",
+    severity = SeverityLevel.WARNING,
+    providesFix = ProvidesFix.REQUIRES_HUMAN_ATTENTION)
+public class MockitoInternalUsage extends BugChecker implements MemberSelectTreeMatcher {
+
+  private static final Matcher<Tree> INSIDE_MOCKITO = packageStartsWith("org.mockito");
+
+  @Override
+  public Description matchMemberSelect(MemberSelectTree tree, VisitorState state) {
+    if (INSIDE_MOCKITO.matches(tree, state)) {
+      return Description.NO_MATCH;
+    }
+    Symbol symbol = ASTHelpers.getSymbol(tree);
+    if (symbol != null && symbol.getQualifiedName().toString().startsWith("org.mockito.internal")) {
+      return describeMatch(tree);
+    }
+    return Description.NO_MATCH;
+  }
+}

subprojects/errorprone/src/test/java/org/mockito/errorprone/bugpatterns/MockitoInternalUsageTest.java

@@ -0,0 +1,105 @@
+/*
+ * Copyright (c) 2017 Mockito contributors
+ * This program is made available under the terms of the MIT License.
+ */
+package org.mockito.errorprone.bugpatterns;
+
+import com.google.errorprone.CompilationTestHelper;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/**
+ * Verify that there are no usages of Mockito internal implementations.
+ *
+ * @author tvanderlippe@google.com (Tim van der Lippe)
+ */
+@RunWith(JUnit4.class)
+public class MockitoInternalUsageTest {
+
+  private CompilationTestHelper compilationHelper;
+
+  @Before
+  public void setUp() {
+    compilationHelper = CompilationTestHelper.newInstance(MockitoInternalUsage.class, getClass());
+  }
+
+  @Test
+  public void testPositiveCases() {
+    compilationHelper
+        .addSourceLines(
+            "Test.java",
+            "import java.io.Serializable;",
+            "class MockitoInternalUsagePositiveCases {",
+            "  public void newObject() {",
+            "    // BUG: Diagnostic contains:",
+            "    new org.mockito.internal.MockitoCore();",
+            "    // BUG: Diagnostic contains:",
+            "    new InternalConsumer(new org.mockito.internal.MockitoCore());",
+            "  }",
+            "  public void staticMethodInvocation() {",
+            "    // BUG: Diagnostic contains:",
+            "    org.mockito.internal.configuration.GlobalConfiguration.validate();",
+            "  }",
+            "  public void variableTypeDeclaration() {",
+            "    // BUG: Diagnostic contains:",
+            "    org.mockito.internal.stubbing.InvocationContainerImpl container = null;",
+            "  }",
+            "  // BUG: Diagnostic contains:",
+            "  class ExtendsClause extends org.mockito.internal.MockitoCore {}",
+            "  // BUG: Diagnostic contains:",
+            "  abstract class ImplementsClause implements"
+                + " org.mockito.internal.junit.MockitoTestListener {}",
+            "  abstract class SecondImplementsClause",
+            "      // BUG: Diagnostic contains:",
+            "      implements Serializable, org.mockito.internal.junit.MockitoTestListener {}",
+            "  // BUG: Diagnostic contains:",
+            "  class ExtendsGeneric<T extends org.mockito.internal.stubbing.InvocationContainerImpl>"
+                + " {}",
+            "  // BUG: Diagnostic contains:",
+            "  class SecondExtendsGeneric<R, T extends"
+                + " org.mockito.internal.stubbing.InvocationContainerImpl> {}",
+            "  class FieldClause {",
+            "    // BUG: Diagnostic contains:",
+            "    org.mockito.internal.MockitoCore core;",
+            "  }",
+            "  class MethodArgumentClause {",
+            "    // BUG: Diagnostic contains:",
+            "    public void methodArgument(org.mockito.internal.MockitoCore core) {}",
+            "  }",
+            "  static class InternalConsumer {",
+            "    // BUG: Diagnostic contains:",
+            "    InternalConsumer(org.mockito.internal.MockitoCore core) {}",
+            "  }",
+            "}")
+        .doTest();
+  }
+
+  @Test
+  public void testPositiveImportsCases() {
+    compilationHelper
+        .addSourceLines(
+            "Test.java",
+            "package foo;",
+            "// BUG: Diagnostic contains:",
+            "import org.mockito.internal.MockitoCore;",
+            "// BUG: Diagnostic contains:",
+            "import org.mockito.internal.stubbing.InvocationContainerImpl;",
+            "// BUG: Diagnostic contains:",
+            "import org.mockito.internal.*;",
+            "class Test {}")
+        .doTest();
+  }
+
+  @Test
+  public void testNegativeCases() {
+    compilationHelper
+        .addSourceLines(
+            "Test.java",
+            "package org.mockito;",
+            "import org.mockito.internal.MockitoCore;",
+            "class Mockito {}")
+        .doTest();
+  }
+}