🔬 Add utility for processing annotations in tests

Introduces AnnotationProcessingUtils, which provides:
- AnnotationExtractor, a class allowing to retrieve one or many
annotations in reverse declaration order from a class or a test
description
- AnnotationProcessor, a rule to simplify the use of the above
extractor in the context of tests (here used as parent for @Features
rule).
- Utility methods to simplify the use of the above extractor in other
contexts (here used in SkipChecks)

Bug: 783160,754778
Change-Id: I8ca0793e1229c6268266c75791a44615b8f93f57
Reviewed-on: https://chromium-review.googlesource.com/789192
Commit-Queue: Nicolas Dossou-Gbété <dgn@chromium.org>
Reviewed-by: Ted Choc <tedchoc@chromium.org>
Reviewed-by: agrieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#520789}

base/BUILD.gn

@@ -2759,11 +2759,12 @@ if (is_android) {
       "test/android/javatests/src/org/chromium/base/test/params/ParameterAnnotations.java",
       "test/android/javatests/src/org/chromium/base/test/params/ParameterProvider.java",
       "test/android/javatests/src/org/chromium/base/test/util/AdvancedMockContext.java",
-      "test/android/javatests/src/org/chromium/base/test/util/AnnotationProcessor.java",
+      "test/android/javatests/src/org/chromium/base/test/util/AnnotationRule.java",
       "test/android/javatests/src/org/chromium/base/test/util/CallbackHelper.java",
       "test/android/javatests/src/org/chromium/base/test/util/CommandLineFlags.java",
       "test/android/javatests/src/org/chromium/base/test/util/DisableIf.java",
       "test/android/javatests/src/org/chromium/base/test/util/DisableIfSkipCheck.java",
+      "test/android/javatests/src/org/chromium/base/test/util/AnnotationProcessingUtils.java",
       "test/android/javatests/src/org/chromium/base/test/util/DisabledTest.java",
       "test/android/javatests/src/org/chromium/base/test/util/EnormousTest.java",
       "test/android/javatests/src/org/chromium/base/test/util/Feature.java",
@@ -2822,6 +2823,7 @@ if (is_android) {
       "android/junit/src/org/chromium/base/process_launcher/ChildProcessConnectionTest.java",
       "test/android/junit/src/org/chromium/base/test/SetUpStatementTest.java",
       "test/android/junit/src/org/chromium/base/test/TestListInstrumentationRunListenerTest.java",
+      "test/android/junit/src/org/chromium/base/test/util/AnnotationProcessingUtilsTest.java",
       "test/android/junit/src/org/chromium/base/test/util/DisableIfTest.java",
       "test/android/junit/src/org/chromium/base/test/util/MinAndroidSdkLevelSkipCheckTest.java",
       "test/android/junit/src/org/chromium/base/test/util/RestrictionSkipCheckTest.java",
@@ -2836,6 +2838,7 @@ if (is_android) {
       ":base_java_process_launcher_test_support",
       ":base_java_test_support",
       "//third_party/android_support_test_runner:runner_java",
+      "//third_party/hamcrest:hamcrest_java",
     ]
     srcjar_deps = [ ":base_build_config_gen" ]
   }

base/test/android/javatests/src/org/chromium/base/test/util/AnnotationProcessor.java

-// Copyright 2016 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-package org.chromium.base.test.util;
-
-import android.support.annotation.Nullable;
-
-import org.junit.rules.ExternalResource;
-import org.junit.runner.Description;
-import org.junit.runners.model.Statement;
-
-import java.lang.annotation.Annotation;
-
-/**
- * Test rule that is activated when a test or its class has a specific annotation.
- * It allows to run some code before the test (and the {@link org.junit.Before}) runs,
- * and guarantees to also run code after.
- *
- * Usage:
- *
- * <pre>
- * public class Test {
- *    &#64;Rule
- *    public AnnotationProcessor<Foo> rule = new AnnotationProcessor(Foo.class) {
- *          &#64;Override
- *          protected void before() { ... }
- *
- *          &#64;Override
- *          protected void after() { ... }
- *    };
- *
- *    &#64;Test
- *    &#64;Foo
- *    public void myTest() { ... }
- * }
- * </pre>
- *
- * @param <T> type of the annotation to match on the test case.
- */
-public abstract class AnnotationProcessor<T extends Annotation> extends ExternalResource {
-    private final Class<T> mAnnotationClass;
-    private Description mTestDescription;
-
-    @Nullable
-    private T mClassAnnotation;
-
-    @Nullable
-    private T mTestAnnotation;
-
-    public AnnotationProcessor(Class<T> annotationClass) {
-        mAnnotationClass = annotationClass;
-    }
-
-    @Override
-    public Statement apply(Statement base, Description description) {
-        mTestDescription = description;
-        mClassAnnotation = description.getTestClass().getAnnotation(mAnnotationClass);
-        mTestAnnotation = description.getAnnotation(mAnnotationClass);
-
-        if (mClassAnnotation == null && mTestAnnotation == null) return base;
-
-        // Return the wrapped statement to execute before() and after().
-        return super.apply(base, description);
-    }
-
-    /** @return {@link Description} of the current test. */
-    protected Description getTestDescription() {
-        return mTestDescription;
-    }
-
-    /** @return the annotation on the test class. */
-    @Nullable
-    protected T getClassAnnotation() {
-        return mClassAnnotation;
-    }
-
-    /** @return the annotation on the test method. */
-    @Nullable
-    protected T getTestAnnotation() {
-        return mTestAnnotation;
-    }
-}

base/test/android/javatests/src/org/chromium/base/test/util/AnnotationRule.java

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.base.test.util;
+
+import org.junit.rules.ExternalResource;
+import org.junit.runner.Description;
+import org.junit.runners.model.Statement;
+
+import java.lang.annotation.Annotation;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.ListIterator;
+
+/**
+ * Test rule that is activated when a test or its class has a specific annotation.
+ * It allows to run some code before the test (and the {@link org.junit.Before}) runs,
+ * and guarantees to also run code after.
+ *
+ * Usage:
+ *
+ * <pre>
+ * public class Test {
+ *    &#64;Rule
+ *    public AnnotationRule rule = new AnnotationRule(Foo.class) {
+ *          &#64;Override
+ *          protected void before() { ... }
+ *
+ *          &#64;Override
+ *          protected void after() { ... }
+ *    };
+ *
+ *    &#64;Test
+ *    &#64;Foo
+ *    public void myTest() { ... }
+ * }
+ * </pre>
+ *
+ * It can also be used to trigger for multiple annotations:
+ *
+ * <pre>
+ * &#64;DisableFoo
+ * public class Test {
+ *    &#64;Rule
+ *    public AnnotationRule rule = new AnnotationRule(EnableFoo.class, DisableFoo.class) {
+ *          &#64;Override
+ *          protected void before() {
+ *            // Loops through all the picked up annotations. For myTest(), it would process
+ *            // DisableFoo first, then EnableFoo.
+ *            for (Annotation annotation : getAnnotations()) {
+ *                if (annotation instanceof EnableFoo) { ... }
+ *                else if (annotation instanceof DisableFoo) { ... }
+ *            }
+ *          }
+ *
+ *          &#64;Override
+ *          protected void after() {
+ *            // For myTest(), would return EnableFoo as it's directly set on the method.
+ *            Annotation a = getClosestAnnotation();
+ *            ...
+ *          }
+ *    };
+ *
+ *    &#64;Test
+ *    &#64;EnableFoo
+ *    public void myTest() { ... }
+ * }
+ * </pre>
+ *
+ * @see AnnotationProcessingUtils.AnnotationExtractor
+ */
+public abstract class AnnotationRule extends ExternalResource {
+    private final AnnotationProcessingUtils.AnnotationExtractor mAnnotationExtractor;
+    private List<Annotation> mCollectedAnnotations;
+    private Description mTestDescription;
+
+    @SafeVarargs
+    public AnnotationRule(Class<? extends Annotation> firstAnnotationType,
+            Class<? extends Annotation>... additionalTypes) {
+        List<Class<? extends Annotation>> mAnnotationTypes = new ArrayList<>();
+        mAnnotationTypes.add(firstAnnotationType);
+        mAnnotationTypes.addAll(Arrays.asList(additionalTypes));
+        mAnnotationExtractor = new AnnotationProcessingUtils.AnnotationExtractor(mAnnotationTypes);
+    }
+
+    @Override
+    public Statement apply(Statement base, Description description) {
+        mTestDescription = description;
+
+        mCollectedAnnotations = mAnnotationExtractor.getMatchingAnnotations(description);
+        if (mCollectedAnnotations.isEmpty()) return base;
+
+        // Return the wrapped statement to execute before() and after().
+        return super.apply(base, description);
+    }
+
+    /** @return {@link Description} of the current test. */
+    protected Description getTestDescription() {
+        return mTestDescription;
+    }
+
+    /**
+     * @return The collected annotations that match the declared type(s).
+     * @throws NullPointerException if this is called before annotations have been collected,
+     * which happens when the rule is applied to the {@link Statement}.
+     */
+    protected List<Annotation> getAnnotations() {
+        return Collections.unmodifiableList(mCollectedAnnotations);
+    }
+
+    /**
+     * @return The closest annotation matching the provided type, or {@code null} if there is none.
+     */
+    @SuppressWarnings("unchecked")
+    protected <A extends Annotation> A getAnnotation(Class<A> annnotationType) {
+        ListIterator<Annotation> iteratorFromEnd =
+                mCollectedAnnotations.listIterator(mCollectedAnnotations.size());
+        while (iteratorFromEnd.hasPrevious()) {
+            Annotation annotation = iteratorFromEnd.previous();
+            if (annnotationType.isAssignableFrom(annotation.annotationType())) {
+                return (A) annotation;
+            }
+        }
+        return null;
+    }
+
+    protected Annotation getClosestAnnotation() {
+        assert !mCollectedAnnotations.isEmpty() : "The rule should not trigger without match.";
+        return mCollectedAnnotations.get(mCollectedAnnotations.size() - 1);
+    }
+}

base/test/android/javatests/src/org/chromium/base/test/util/DisableIfSkipCheck.java

@@ -24,7 +24,8 @@ public class DisableIfSkipCheck extends SkipCheck {
     @Override
     public boolean shouldSkip(FrameworkMethod method) {
         if (method == null) return true;
-        for (DisableIf.Build v : getAnnotations(method, DisableIf.Build.class)) {
+        for (DisableIf.Build v : AnnotationProcessingUtils.getAnnotations(
+                     method.getMethod(), DisableIf.Build.class)) {
             if (abi(v) && hardware(v) && product(v) && sdk(v)) {
                 if (!v.message().isEmpty()) {
                     Log.i(TAG, "%s is disabled: %s", method.getName(), v.message());
@@ -33,7 +34,8 @@ public class DisableIfSkipCheck extends SkipCheck {
             }
         }
 
-        for (DisableIf.Device d : getAnnotations(method, DisableIf.Device.class)) {
+        for (DisableIf.Device d : AnnotationProcessingUtils.getAnnotations(
+                     method.getMethod(), DisableIf.Device.class)) {
             for (String deviceType : d.type()) {
                 if (deviceTypeApplies(deviceType)) {
                     Log.i(TAG, "Test " + method.getDeclaringClass().getName() + "#"

base/test/android/javatests/src/org/chromium/base/test/util/MinAndroidSdkLevelSkipCheck.java

@@ -27,7 +27,8 @@ public class MinAndroidSdkLevelSkipCheck extends SkipCheck {
     @Override
     public boolean shouldSkip(FrameworkMethod frameworkMethod) {
         int minSdkLevel = 0;
-        for (MinAndroidSdkLevel m : getAnnotations(frameworkMethod, MinAndroidSdkLevel.class)) {
+        for (MinAndroidSdkLevel m : AnnotationProcessingUtils.getAnnotations(
+                     frameworkMethod.getMethod(), MinAndroidSdkLevel.class)) {
             minSdkLevel = Math.max(minSdkLevel, m.value());
         }
         if (Build.VERSION.SDK_INT < minSdkLevel) {

base/test/android/javatests/src/org/chromium/base/test/util/RestrictionSkipCheck.java

@@ -35,7 +35,8 @@ public class RestrictionSkipCheck extends SkipCheck {
     public boolean shouldSkip(FrameworkMethod frameworkMethod) {
         if (frameworkMethod == null) return true;
 
-        for (Restriction restriction : getAnnotations(frameworkMethod, Restriction.class)) {
+        for (Restriction restriction : AnnotationProcessingUtils.getAnnotations(
+                     frameworkMethod.getMethod(), Restriction.class)) {
             for (String restrictionVal : restriction.value()) {
                 if (restrictionApplies(restrictionVal)) {
                     Log.i(TAG, "Test " + frameworkMethod.getDeclaringClass().getName() + "#"

base/test/android/javatests/src/org/chromium/base/test/util/SkipCheck.java

@@ -10,11 +10,7 @@ import org.junit.runners.model.FrameworkMethod;
 
 import org.chromium.base.Log;
 
-import java.lang.annotation.Annotation;
-import java.lang.reflect.AnnotatedElement;
 import java.lang.reflect.Method;
-import java.util.ArrayList;
-import java.util.List;
 
 /**
  * Check whether a test case should be skipped.
@@ -49,23 +45,5 @@ public abstract class SkipCheck {
             return false;
         }
     }
-
-    protected static <T extends Annotation> List<T> getAnnotations(FrameworkMethod frameworkMethod,
-            Class<T> annotationClass) {
-        return getAnnotations(frameworkMethod.getMethod(), annotationClass);
-    }
-
-    protected static <T extends Annotation> List<T> getAnnotations(AnnotatedElement element,
-            Class<T> annotationClass) {
-        AnnotatedElement parent = (element instanceof Method)
-                ? ((Method) element).getDeclaringClass()
-                : ((Class) element).getSuperclass();
-        List<T> annotations = (parent == null)
-                ? new ArrayList<T>()
-                : getAnnotations(parent, annotationClass);
-        T annotation = element.getAnnotation(annotationClass);
-        if (annotation != null) annotations.add(annotation);
-        return annotations;
-    }
 }
 

base/test/android/junit/src/org/chromium/base/test/util/SkipCheckTest.java

@@ -10,7 +10,6 @@ import org.junit.Assert;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.junit.runners.model.FrameworkMethod;
-
 import org.robolectric.annotation.Config;
 
 import org.chromium.testing.local.LocalRobolectricTestRunner;
@@ -30,7 +29,7 @@ public class SkipCheckTest {
     private static class TestableSkipCheck extends SkipCheck {
         public static <T extends Annotation> List<T> getAnnotationsForTesting(
                 AnnotatedElement element, Class<T> annotationClass) {
-            return getAnnotations(element, annotationClass);
+            return AnnotationProcessingUtils.getAnnotations(element, annotationClass);
         }
 
         @Override

chrome/test/android/javatests/src/org/chromium/chrome/test/util/browser/ChromeHome.java

@@ -11,13 +11,12 @@ import android.os.StrictMode;
 import android.text.TextUtils;
 
 import org.chromium.base.CommandLine;
-import org.chromium.base.test.util.AnnotationProcessor;
+import org.chromium.base.test.util.AnnotationRule;
 import org.chromium.chrome.browser.ChromeFeatureList;
 import org.chromium.chrome.browser.preferences.ChromePreferenceManager;
 import org.chromium.chrome.browser.util.FeatureUtilities;
 
 import java.lang.annotation.ElementType;
-import java.lang.annotation.Inherited;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
@@ -29,7 +28,6 @@ import java.lang.annotation.Target;
  * @see ChromeHome.Processor
  * @see FeatureUtilities#isChromeHomeEnabled()
  */
-@Inherited
 @Retention(RetentionPolicy.RUNTIME)
 @Target({ElementType.METHOD, ElementType.TYPE})
 public @interface ChromeHome {
@@ -43,7 +41,7 @@ public @interface ChromeHome {
      * used by explicitly calling methods ({@link #setPrefs(boolean)} and {@link #clearTestState()})
      * or by using the {@link ChromeHome} annotation on tests.
      */
-    class Processor extends AnnotationProcessor<ChromeHome> {
+    class Processor extends AnnotationRule {
         private Boolean mOldState;
 
         public Processor() {
@@ -52,7 +50,7 @@ public @interface ChromeHome {
 
         @Override
         protected void before() throws Throwable {
-            boolean enabled = getRequestedState();
+            boolean enabled = getAnnotation(ChromeHome.class).value();
             if (enabled) {
                 Features.getInstance().enable(ChromeFeatureList.CHROME_HOME);
             } else {
@@ -108,12 +106,5 @@ public @interface ChromeHome {
 
             commandLine.appendSwitch(ENABLE_FLAGS);
         }
-
-        private boolean getRequestedState() {
-            if (getTestAnnotation() != null) return getTestAnnotation().value();
-            if (getClassAnnotation() != null) return getClassAnnotation().value();
-
-            throw new IllegalStateException("Rule called with no annotation");
-        }
     }
 }

chrome/test/android/javatests/src/org/chromium/chrome/test/util/browser/Features.java

@@ -7,13 +7,11 @@ package org.chromium.chrome.test.util.browser;
 import android.support.annotation.Nullable;
 import android.text.TextUtils;
 
-import org.junit.rules.ExternalResource;
-import org.junit.runner.Description;
-import org.junit.runners.model.Statement;
-
 import org.chromium.base.CommandLine;
+import org.chromium.base.test.util.AnnotationRule;
 import org.chromium.chrome.browser.ChromeFeatureList;
 
+import java.lang.annotation.Annotation;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.util.Collections;
@@ -151,23 +149,14 @@ public class Features {
      * to enable, or get rid of exceptions when the production code tries to check for enabled
      * features.
      */
-    private static abstract class Processor extends ExternalResource {
-        private Description mDescription;
-
-        @Override
-        public Statement apply(Statement base, Description description) {
-            mDescription = description;
-            return super.apply(base, description);
+    private static abstract class Processor extends AnnotationRule {
+        public Processor() {
+            super(EnableFeatures.class, DisableFeatures.class);
         }
 
         @Override
         protected void before() throws Throwable {
-            collectDisabledFeatures(
-                    mDescription.getTestClass().getAnnotation(DisableFeatures.class));
-            collectEnabledFeatures(mDescription.getTestClass().getAnnotation(EnableFeatures.class));
-            collectDisabledFeatures(mDescription.getAnnotation(DisableFeatures.class));
-            collectEnabledFeatures(mDescription.getAnnotation(EnableFeatures.class));
-
+            collectFeatures();
             applyFeatures();
         }
 
@@ -178,12 +167,14 @@ public class Features {
 
         abstract protected void applyFeatures();
 
-        private void collectEnabledFeatures(@Nullable EnableFeatures annotation) {
-            if (annotation != null) getInstance().enable(annotation.value());
-        }
-
-        private void collectDisabledFeatures(@Nullable DisableFeatures annotation) {
-            if (annotation != null) getInstance().disable(annotation.value());
+        private void collectFeatures() {
+            for (Annotation annotation : getAnnotations()) {
+                if (annotation instanceof EnableFeatures) {
+                    getInstance().enable(((EnableFeatures) annotation).value());
+                } else if (annotation instanceof DisableFeatures) {
+                    getInstance().disable(((DisableFeatures) annotation).value());
+                }
+            }
         }
     }
 }