List Java Instru Test Information From JUnit Runner

base/test/android/javatests/src/org/chromium/base/test/BaseChromiumAndroidJUnitRunner.java

 // Copyright 2017 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;
 
+import android.app.Activity;
 import android.app.Application;
+import android.app.Instrumentation;
 import android.content.Context;
+import android.os.Bundle;
+import android.support.test.internal.runner.RunnerArgs;
+import android.support.test.internal.runner.TestExecutor;
+import android.support.test.internal.runner.TestRequest;
+import android.support.test.internal.runner.TestRequestBuilder;
 import android.support.test.runner.AndroidJUnitRunner;
 
+import org.chromium.base.Log;
 import org.chromium.base.multidex.ChromiumMultiDexInstaller;
 
 /**
- * A custom AndroidJUnitRunner that supports multidex installer.
+ * A custom AndroidJUnitRunner that supports multidex installer and list out test information.
  *
  * This class is the equivalent of BaseChromiumInstrumentationTestRunner in JUnit3. Please
  * beware that is this not a class runner. It is declared in test apk AndroidManifest.xml
  * <instrumentation>
  */
 public class BaseChromiumAndroidJUnitRunner extends AndroidJUnitRunner {
+    private static final String LIST_ALL_TESTS_FLAG =
+            "org.chromium.base.test.BaseChromiumAndroidJUnitRunner.TestList";
+    private static final String TAG = "BaseJUnitRunner";
+
+    private Bundle mArguments;
+
     @Override
     public Application newApplication(ClassLoader cl, String className, Context context)
             throws ClassNotFoundException, IllegalAccessException, InstantiationException {
         ChromiumMultiDexInstaller.install(new BaseChromiumRunnerCommon.MultiDexContextWrapper(
                 getContext(), getTargetContext()));
         BaseChromiumRunnerCommon.reorderDexPathElements(cl, getContext(), getTargetContext());
         return super.newApplication(cl, className, context);
     }
+
+    @Override
+    public void onCreate(Bundle arguments) {
+        super.onCreate(arguments);
+        mArguments = arguments;
+    }
+
+    /**
+     * Add TestListInstrumentationRunListener when argument ask the runner to list tests info.
+     *
+     * The running mechanism when argument has "listAllTests" is equivalent to that of
+     * {@link android.support.test.runner.AndroidJUnitRunner#onStart()} except it adds
+     * only TestListInstrumentationRunListener to monitor the tests.
+     */
+    @Override
+    public void onStart() {
+        if (mArguments != null && mArguments.getString(LIST_ALL_TESTS_FLAG) != null) {
+            Log.w(TAG, "Runner will list out tests info in JSON without running tests");
+            listTests(); // Intentionally not calling super.onStart() to avoid additional work.
+        } else {
+            super.onStart();
+        }
+    }
+
+    private void listTests() {
+        Bundle results = new Bundle();
+        try {
+            TestExecutor.Builder executorBuilder = new TestExecutor.Builder(this);
+            executorBuilder.addRunListener(new TestListInstrumentationRunListener(
+                    mArguments.getString(LIST_ALL_TESTS_FLAG)));
+            TestRequest listTestRequest = createListTestRequest(mArguments);
+            results = executorBuilder.build().execute(listTestRequest);
+        } catch (RuntimeException e) {
+            String msg = "Fatal exception when running tests";
+            Log.e(TAG, msg, e);
+            // report the exception to instrumentation out
+            results.putString(Instrumentation.REPORT_KEY_STREAMRESULT,
+                    msg + "\n" + Log.getStackTraceString(e));
+        }
+        finish(Activity.RESULT_OK, results);
+    }
+
+    private TestRequest createListTestRequest(Bundle arguments) {
+        RunnerArgs runnerArgs =
+                new RunnerArgs.Builder().fromManifest(this).fromBundle(arguments).build();
+        TestRequestBuilder builder = new TestRequestBuilder(this, arguments);
+        builder.addApkToScan(getContext().getPackageCodePath());
+        builder.addFromRunnerArgs(runnerArgs);
+        return builder.build();
+    }
 }