Create MemoryTrackingTestCase for convenient heap dumping

/*

 * Copyright (C) 2022 The Android Open Source Project

 *

 * Licensed under the Apache License, Version 2.0 (the "License");

 * you may not use this file except in compliance with the License.

 * You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.android.systemui;

import android.os.Debug;

import android.util.Log;

import org.junit.AfterClass;

import org.junit.Before;

import java.io.File;

import java.io.IOException;

/**

 * Convenience class for grabbing a heap dump after a test class is run.

 *

 * To use:

 * - locally edit your test class to inherit from MemoryTrackingTestCase instead of SysuiTestCase

 * - Watch the logcat with tag MEMORY to see the path to the .ahprof file

 * - adb pull /path/to/something.ahprof

 * - Download ahat from https://sites.google.com/corp/google.com/ahat/home

 * - java -jar ~/Downloads/ahat-1.7.2.jar something.hprof

 * - Watch output for next steps

 * - Profit and fix leaks!

 */

public class MemoryTrackingTestCase extends SysuiTestCase {

    private static File sFilesDir = null;

    private static String sLatestTestClassName = null;

    @Before public void grabFilesDir() {

        if (sFilesDir == null) {

            sFilesDir = mContext.getFilesDir();

        }

        sLatestTestClassName = getClass().getName();

    }

    @AfterClass

    public static void dumpHeap() throws IOException {

        if (sFilesDir == null) {

            Log.e("MEMORY", "Somehow no test cases??");

            return;

        }

        mockitoTearDown();

        Log.w("MEMORY", "about to dump heap");

        File path = new File(sFilesDir, sLatestTestClassName + ".ahprof");

        Debug.dumpHprofData(path.getPath());

        Log.w("MEMORY", "did it!  Location: " + path);

    }

}