问题

AndroidJUnitRunner 原理（https://yuque.antfin.com/xiaobao.spf/ad2gcp/ktqa9u）
编译产物（自动化测试生成的2个apk对比）
启动方式（主要研究AndroidJUnitRunner如何被调起）
运行方式（研究 espresso和 uiautomator原理，如何模拟操作）
espresso和uiautomator是否可以打包到主apk

编译产物

执行自动化测试会编译出两个apk，我看到之后是很懵逼的，心里会涌现出了无数个🦙，这么多年竟然忽略了这个细节。

dependencies {
    implementation 'androidx.appcompat:appcompat:1.3.0'
    implementation 'com.google.android.material:material:1.4.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.0.4'
    testImplementation 'junit:junit:4.+'
    androidTestImplementation 'androidx.test.ext:junit:1.1.3'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
}

1.app-debug.apk

1.1 Manifest.xml

   <manifest
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:versionCode="1"
    android:versionName="1.0"
    android:compileSdkVersion="30"
    android:compileSdkVersionCodename="11"
    package="com.demo.sample"
    platformBuildVersionCode="30"
    platformBuildVersionName="11">
    ...
</manifest>

package为com.demo.sample

1.2 依赖
正常的依赖了gradle中配置的依赖

2.app-debug-androidTest.apk

2.1Manifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:compileSdkVersion="30"
    android:compileSdkVersionCodename="11"
    package="com.demo.sample.test" 
    platformBuildVersionCode="30"
    platformBuildVersionName="11">

    <uses-sdk
        android:minSdkVersion="16"
        android:targetSdkVersion="30" />

    <instrumentation
        android:label="Tests for com.demo.sample"
        android:name="androidx.test.runner.AndroidJUnitRunner"
        android:targetPackage="com.demo.sample"
        android:handleProfiling="false"
        android:functionalTest="false" />
		...
</manifest>

这里有个细节，manifest中package是com.demo.sample.test，和实际apk相比多了.test

2.2 依赖

debugAndroidTestRuntimeClasspath - Resolved configuration for runtime for variant: debugAndroidTest
+--- androidx.test.ext:junit:1.1.3
|    +--- junit:junit:4.12
|    |    \--- org.hamcrest:hamcrest-core:1.3
|    +--- androidx.test:core:1.4.0
|    |    +--- androidx.annotation:annotation:1.0.0 -> 1.2.0
|    |    +--- androidx.test:monitor:1.4.0
|    |    |    \--- androidx.annotation:annotation:1.0.0 -> 1.2.0
|    |    \--- androidx.lifecycle:lifecycle-common:2.0.0 -> 2.3.1
|    |         \--- androidx.annotation:annotation:1.1.0 -> 1.2.0
|    +--- androidx.test:monitor:1.4.0 (*)
|    \--- androidx.annotation:annotation:1.0.0 -> 1.2.0
+--- androidx.test.espresso:espresso-core:3.4.0
|    +--- androidx.test:runner:1.4.0
|    |    +--- androidx.annotation:annotation:1.0.0 -> 1.2.0
|    |    +--- androidx.test:monitor:1.4.0 (*)
|    |    +--- androidx.test.services:storage:1.4.0
|    |    |    +--- androidx.test:monitor:1.4.0 (*)
|    |    |    \--- com.google.code.findbugs:jsr305:2.0.1
|    |    \--- junit:junit:4.12 (*)
|    +--- androidx.test.espresso:espresso-idling-resource:3.4.0
|    +--- com.squareup:javawriter:2.1.1
|    +--- javax.inject:javax.inject:1
|    +--- org.hamcrest:hamcrest-library:1.3
|    |    \--- org.hamcrest:hamcrest-core:1.3
|    +--- org.hamcrest:hamcrest-integration:1.3
|    |    \--- org.hamcrest:hamcrest-library:1.3 (*)
|    \--- com.google.code.findbugs:jsr305:2.0.1
+--- androidx.annotation:annotation:{strictly 1.2.0} -> 1.2.0 (c) //这可真是一万个🦙呀，根本不知道为啥被引入的，
\--- androidx.lifecycle:lifecycle-common:{strictly 2.3.1} -> 2.3.1 (c) // 只能看源码，这个任务留给以后吧

综上，不同的地方基本只有Manifest中的不同，其他资源正常。

启动方式

正确流程：
am可执行文件 ->
app_process可执行文件 ->
AM.java ->
Instrument.java ->
AMS ->
Process ->
ActivityThread.java ->
Instrumentation.java

一般am 直接调用AMS服务，但是am instrument 时为特殊场景

1	adb shell am instrument -w -m -e debug false -e class 'com.demo.sample.ExampleInstrumentedTest' com.demo.sample.test/androidx.test.runner.AndroidJUnitRunner

根据aosp经验，adb shell am 会调用AMS中的onShellCommand方法

ActivityManagerService.java

public class ActivityManagerService extends IActivityManager.Stub
        implements Watchdog.Monitor, BatteryStatsImpl.BatteryCallback {	
	@Override
    public void onShellCommand(FileDescriptor in, FileDescriptor out,
            FileDescriptor err, String[] args, ShellCallback callback,
            ResultReceiver resultReceiver) {
        (new ActivityManagerShellCommand(this, false)).exec(
                this, in, out, err, args, callback, resultReceiver);
    }
}

ActivityManagerShellCommand.java

final class ActivityManagerShellCommand extends ShellCommand {
    @Override
    public int onCommand(String cmd) {
        if (cmd == null) {
            return handleDefaultCommands(cmd);
        }
        final PrintWriter pw = getOutPrintWriter();
        try {
            switch (cmd) {
                ...
                    
                case "instrument":
                    getOutPrintWriter().println("Error: must be invoked through 'am instrument'.");
                    return -1;
               	...
                default:
                    return handleDefaultCommands(cmd);
            }
        } catch (RemoteException e) {
            pw.println("Remote exception: " + e);
        }
        return -1;
    }
}

又一个🦙出现在我的眼前，这儿直接是打印一个日志，那肯定不是走这里了，这样的话只能从cmd 去跟代码了。
如果不懂cmd参考：https://yuque.antfin.com/xiaobao.spf/ad2gcp/gm5kr7

1	adb shell cmd -l

上面的命令可以列出手机支持的服务，可惜列出来的服务没有am，现在我们应该去手机/system/bin目录下去找am

am就是一个shell脚本

#!/system/bin/sh

if [ "$1" != "instrument" ] ; then
    cmd activity "$@"
else  //我们关注点是else这个分支
    base=/system
    export CLASSPATH=$base/framework/am.jar
    exec app_process $base/bin com.android.commands.am.Am "$@"
fi

这段代码不难理解， args = [am instrument ],如果$1是instrument，则走else，这里直接执行了/system/bin/app_process，这里我们直接看com.android.commands.am.Am代码吧，这里给出com.android.commands.am.Am文件吧
如果不懂app_process参考:https://yuque.antfin.com/xiaobao.spf/ad2gcp/inweh2

com.android.commands.am.Am.java

public class Am extends BaseCommand {


    public static void main(String[] args) {
        (new Am()).run(args);
    }

    @Override
    public void onRun() throws Exception {

        mAm = ActivityManager.getService();
        if (mAm == null) {
            System.err.println(NO_SYSTEM_ERROR_CODE);
            throw new AndroidException("Can't connect to activity manager; is the system running?");
        }

        mPm = IPackageManager.Stub.asInterface(ServiceManager.getService("package"));
        if (mPm == null) {
            System.err.println(NO_SYSTEM_ERROR_CODE);
            throw new AndroidException("Can't connect to package manager; is the system running?");
        }

        String op = nextArgRequired(); //获取args

        if (op.equals("instrument")) {
            runInstrument();  //执行这里
        } else {
            runAmCmd(getRawArgs());//调回了ams
        }
    }

    public void runInstrument() throws Exception {
        Instrument instrument = new Instrument(mAm, mPm);
		// adb shell am instrument
        // -w 
        // -m    
        // -e debug false 
        // -e class 'com.demo.sample.ExampleInstrumentedTest' 
        // com.demo.sample.test/androidx.test.runner.AndroidJUnitRunner
        String opt;
        while ((opt=nextOption()) != null) {
            if (opt.equals("-w")) {
                instrument.wait = true;
            } else if (opt.equals("-m")) {
                instrument.protoStd = true;
            } else if (opt.equals("-e")) {
                final String argKey = nextArgRequired();
                final String argValue = nextArgRequired();
                instrument.args.putString(argKey, argValue);
            }
        }

        if (instrument.userId == UserHandle.USER_ALL) {
            System.err.println("Error: Can't start instrumentation with user 'all'");
            return;
        }
		// componentNameArg = com.demo.sample.test/androidx.test.runner.AndroidJUnitRunner
        instrument.componentNameArg = nextArgRequired(); 

        instrument.run();
    }
}

Instrument.java

public class Instrument {
   
    public void run() throws Exception {
        StatusReporter reporter = null;
        float[] oldAnims = null;

        try {
            
            // Choose whether we have to wait for the results.
            InstrumentationWatcher watcher = null;
            // 这里竟然有 UiAutomationConnection，一定要记住，后续会再次提到
            UiAutomationConnection connection = null;
            if (reporter != null) {
                watcher = new InstrumentationWatcher(reporter);
                connection = new UiAutomationConnection();
            }

            // 这里通过PMS 查询 instrument，原理就是通过手机里面安装的所有Manifest.xml 寻找
            final ComponentName cn = parseComponentName(componentNameArg);

          
        	// 通过ams 启动 startInstrumentation ，这样就启动了
            if (!mAm.startInstrumentation(cn, profileFile, flags, args, watcher, connection, userId,
                        abi)) {
                throw new AndroidException("INSTRUMENTATION_FAILED: " + cn.flattenToString());
            }

        } catch (Exception ex) {
           
        } finally {
            
        }
    }  
}

下一步应该在AMS中找 startInstrumentation方法，有个自己编译的aosp手机是如此的重要，下面截图是AMS调试

public class ActivityManagerService extends IActivityManager.Stub
        implements Watchdog.Monitor, BatteryStatsImpl.BatteryCallback {	
        
	public boolean startInstrumentation(ComponentName className,
            String profileFile, int flags, Bundle arguments,
            IInstrumentationWatcher watcher, IUiAutomationConnection uiAutomationConnection,
            int userId, String abiOverride) {
       
        synchronized(this) {
            
            ActiveInstrumentation activeInstr = new ActiveInstrumentation(this);
            activeInstr.mClass = className;
            String defProcess = ai.processName;;
            if (ii.targetProcesses == null) {
                activeInstr.mTargetProcesses = new String[]{ai.processName};
            } else if (ii.targetProcesses.equals("*")) {
                activeInstr.mTargetProcesses = new String[0];
            } else {
                activeInstr.mTargetProcesses = ii.targetProcesses.split(",");
                defProcess = activeInstr.mTargetProcesses[0];
            }
            activeInstr.mTargetInfo = ai;
            activeInstr.mProfileFile = profileFile;
            activeInstr.mArguments = arguments;
            activeInstr.mWatcher = watcher;
            activeInstr.mUiAutomationConnection = uiAutomationConnection;
            activeInstr.mResultClass = className;
            activeInstr.mHasBackgroundActivityStartsPermission = checkPermission(
                    START_ACTIVITIES_FROM_BACKGROUND, callingPid, callingUid)
                            == PackageManager.PERMISSION_GRANTED;

            boolean disableHiddenApiChecks = ai.usesNonSdkApi()
                    || (flags & INSTR_FLAG_DISABLE_HIDDEN_API_CHECKS) != 0;
            if (disableHiddenApiChecks) {
                enforceCallingPermission(android.Manifest.permission.DISABLE_HIDDEN_API_CHECKS,
                        "disable hidden API checks");
            }
            final boolean mountExtStorageFull = isCallerShell()
                    && (flags & INSTR_FLAG_MOUNT_EXTERNAL_STORAGE_FULL) != 0;

            final long origId = Binder.clearCallingIdentity();
            // Instrumentation can kill and relaunch even persistent processes
            forceStopPackageLocked(ii.targetPackage, -1, true, false, true, true, false, userId,
                    "start instr");
            // Inform usage stats to make the target package active
            if (mUsageStatsService != null) {
                mUsageStatsService.reportEvent(ii.targetPackage, userId,
                        UsageEvents.Event.SYSTEM_INTERACTION);
            }
            //<instrumentation
        	//  android:label="Tests for com.demo.sample"
        	//  android:name="androidx.test.runner.AndroidJUnitRunner"
        	//  android:targetPackage="com.demo.sample"
        	//  android:handleProfiling="false"
        	//  android:functionalTest="false" />
            
            // ProcessRecord 中的ai是 targetPackage，所以启动的进程是非 test apk的进程
            
            
			//启动一个进程，这里的ai很重要，因为这是从instrumentation取出来的targetPackage
            //看图吧
            ProcessRecord app = addAppLocked(ai, defProcess, false, disableHiddenApiChecks,
                    mountExtStorageFull, abiOverride);
            
            // 这里是关键        
            app.setActiveInstrumentation(activeInstr);
            activeInstr.mFinished = false;
            activeInstr.mRunningProcesses.add(app);
            if (!mActiveInstrumentation.contains(activeInstr)) {
                mActiveInstrumentation.add(activeInstr);
            }
            Binder.restoreCallingIdentity(origId);
        }

        return true;
    }
}

这里的链路比较长，我这里直接放出代码，有兴趣可以自己跟一下代码

public final class ActivityThread extends ClientTransactionHandler {
    
    private void handleBindApplication(AppBindData data) {
        // 这里启动了 com.demo.sample.test/androidx.test.runner.AndroidJUnitRunner
        try {
            final ClassLoader cl = instrContext.getClassLoader();
            mInstrumentation = (Instrumentation)
                    cl.loadClass(data.instrumentationName.getClassName()).newInstance();
        } catch (Exception e) {
            throw new RuntimeException(
                    "Unable to instantiate instrumentation "
                            + data.instrumentationName + ": " + e.toString(), e);
        }

        final ComponentName component = new ComponentName(ii.packageName, ii.name);
        mInstrumentation.init(this, instrContext, appContext, component,
                data.instrumentationWatcher, data.instrumentationUiAutomationConnection);
    }
}

启动的是app-debug.apk，为什么可以加载app-debug-androidTest.apk中的AndroidJUnitRunner ？

public final class ActivityThread extends ClientTransactionHandler {
    
    private void handleBindApplication(AppBindData data) {
        final InstrumentationInfo ii;
        if (data.instrumentationName != null) {
            try {
                ii = new ApplicationPackageManager(null, getPackageManager())
                        .getInstrumentationInfo(data.instrumentationName, 0);
            } catch (PackageManager.NameNotFoundException e) {
                throw new RuntimeException(
                        "Unable to find instrumentation info for: " + data.instrumentationName);
            }

            // Warn of potential ABI mismatches.
            if (!Objects.equals(data.appInfo.primaryCpuAbi, ii.primaryCpuAbi)
                    || !Objects.equals(data.appInfo.secondaryCpuAbi, ii.secondaryCpuAbi)) {
                Slog.w(TAG, "Package uses different ABI(s) than its instrumentation: "
                        + "package[" + data.appInfo.packageName + "]: "
                        + data.appInfo.primaryCpuAbi + ", " + data.appInfo.secondaryCpuAbi
                        + " instrumentation[" + ii.packageName + "]: "
                        + ii.primaryCpuAbi + ", " + ii.secondaryCpuAbi);
            }

            mInstrumentationPackageName = ii.packageName;
            mInstrumentationAppDir = ii.sourceDir;
            mInstrumentationSplitAppDirs = ii.splitSourceDirs;
            mInstrumentationLibDir = getInstrumentationLibrary(data.appInfo, ii);
            mInstrumentedAppDir = data.info.getAppDir();
            mInstrumentedSplitAppDirs = data.info.getSplitAppDirs();
            mInstrumentedLibDir = data.info.getLibDir();
        } else {
            ii = null;
        }
        
		// Continue loading instrumentation.
        if (ii != null) {
            ApplicationInfo instrApp;
            try {
                instrApp = getPackageManager().getApplicationInfo(ii.packageName, 0,
                        UserHandle.myUserId());
            } catch (RemoteException e) {
                instrApp = null;
            }
            if (instrApp == null) {
                instrApp = new ApplicationInfo();
            }
            ii.copyTo(instrApp);
            instrApp.initForUser(UserHandle.myUserId());
            
            // instrApp 为 instrumentation 的applicationInfo，即 test apk
            final LoadedApk pi = getPackageInfo(instrApp, data.compatInfo,
                    appContext.getClassLoader(), false, true, false);

            // The test context's op package name == the target app's op package name, because
            // the app ops manager checks the op package name against the real calling UID,
            // which is what the target package name is associated with.
            final ContextImpl instrContext = ContextImpl.createAppContext(this, pi,
                    appContext.getOpPackageName());

            try {
                final ClassLoader cl = instrContext.getClassLoader();
                mInstrumentation = (Instrumentation)
                    cl.loadClass(data.instrumentationName.getClassName()).newInstance();
            } catch (Exception e) {
                throw new RuntimeException(
                    "Unable to instantiate instrumentation "
                    + data.instrumentationName + ": " + e.toString(), e);
            }

            final ComponentName component = new ComponentName(ii.packageName, ii.name);
            mInstrumentation.init(this, instrContext, appContext, component,
                    data.instrumentationWatcher, data.instrumentationUiAutomationConnection);        
        
    }
}

总结为一句话，LoadedApk会帮我们把app-debug-androidTest.apk进行装载。很多插件化的原理也是如此，我知道的ACDD就是这样。

紧接着AndroidJUnitRunner就被启动了，
AndroidJUnitRunner原理看着这个 https://yuque.antfin.com/xiaobao.spf/ad2gcp/ktqa9u

运行方式

AndroidJUnitRunner的运行这里不讲，主要看uiautomator的运行。

UiDevice

public class UiDevice implements Searchable {
    /**
     * Returns the first object to match the {@code selector} criteria,
     * or null if no matching objects are found.
     */
    public UiObject2 findObject(BySelector selector) {
        AccessibilityNodeInfo node = ByMatcher.findMatch(this, selector, getWindowRoots());
        return node != null ? new UiObject2(this, selector, node) : null;
    }
    
    AccessibilityNodeInfo[] getWindowRoots() {
        waitForIdle();

        Set<AccessibilityNodeInfo> roots = new HashSet();

        // Start with the active window, which seems to sometimes be missing from the list returned
        // by the UiAutomation.
        AccessibilityNodeInfo activeRoot = getUiAutomation().getRootInActiveWindow();
        if (activeRoot != null) {
            roots.add(activeRoot);
        }

        // Support multi-window searches for API level 21 and up.
        if (UiDevice.API_LEVEL_ACTUAL >= Build.VERSION_CODES.LOLLIPOP) {
            for (AccessibilityWindowInfo window : getUiAutomation().getWindows()) {
                AccessibilityNodeInfo root = window.getRoot();
                if (root == null) {
                    Log.w(LOG_TAG, String.format("Skipping null root node for window: %s",
                            window.toString()));
                    continue;
                }
                roots.add(root);
            }
        }
        return roots.toArray(new AccessibilityNodeInfo[roots.size()]);
    }
    
}

很重要的方法：getWindowRoots 调用了UiAutomation的getRootInActiveWindow方法

UiAutomation

public final class UiAutomation {
    // window 根
    public AccessibilityNodeInfo getRootInActiveWindow() {
        final int connectionId;
        synchronized (mLock) {
            throwIfNotConnectedLocked();
            connectionId = mConnectionId;
        }
        // Calling out without a lock held.
        // 链接 Acc服务的时候会存下来
        return AccessibilityInteractionClient.getInstance()
                .getRootInActiveWindow(connectionId);
    }	
    
    public void connect(int flags) {
        synchronized (mLock) {
			// 接受Acc的回调 binder stub      
            mClient = new IAccessibilityServiceClientImpl(mRemoteCallbackThread.getLooper());
        }
        try {
            // binder proxy 链接ACC服务，将mClient传递给Acc服务
            mUiAutomationConnection.connect(mClient, flags);
            mFlags = flags;
        } catch (RemoteException re) {
            throw new RuntimeException("Error while connecting " + this, re);
        }
    }
    
    

}

UiAutomationConnection binder Proxy 帮助链接ACC
IAccessibilityServiceClientImpl binder Stub 接受acc的回调

Instrumentation 你没有看错 ActivityThread里面的也是它，自动化测试中AndroidJUnitRunner继承它。

public class Instrumentation {
    // 有Instrumentation时调用，目前自动化测试会设置
   final void init(ActivityThread thread,
            Context instrContext, Context appContext, ComponentName component, 
            IInstrumentationWatcher watcher, IUiAutomationConnection uiAutomationConnection) {
        mThread = thread;
        mMessageQueue = mThread.getLooper().myQueue();
        mInstrContext = instrContext;
        mAppContext = appContext;
        mComponent = component;
        mWatcher = watcher;
        mUiAutomationConnection = uiAutomationConnection; // 上面有提到这个
    }
    
    //正常调用
    final void basicInit(ActivityThread thread) {
        mThread = thread;
    }
    
   	// 触发 Acc服务 连接，上面获取 AccessibilityNodeInfo时也会触发
    public UiAutomation getUiAutomation(@UiAutomationFlags int flags) {
        boolean mustCreateNewAutomation = (mUiAutomation == null) || (mUiAutomation.isDestroyed());

        if (mUiAutomationConnection != null) {
            if (!mustCreateNewAutomation && (mUiAutomation.getFlags() == flags)) {
                return mUiAutomation;
            }
            if (mustCreateNewAutomation) {
                mUiAutomation = new UiAutomation(getTargetContext().getMainLooper(),
                        mUiAutomationConnection);
            } else {
                mUiAutomation.disconnect();
            }
            //链接Acc服务
            mUiAutomation.connect(flags);
            return mUiAutomation;
        }
        return null;
    }
    
    
    
}

espresso和uiautomator是否可以打包到主apk

根据上面启动方式，最终是启动了1个apk，通过LoadedApk装载了另一个apk，所以无论espresso和uiautomator在哪个apk中，都不会影响自动化测试运行。

利用Intrumentation是否可以搞黑科技

是否可以通过一个apk去运行另一个apk的instrument ，然后运行自动化测试的模拟操作？

第一个apk中手动注册一个 MyInstrumentation

<instrumentation
        android:label="Tests for com.demo.sample"
        android:name=".MyInstrumentation"
        android:targetPackage="com.demo.sample"
        android:handleProfiling="false"
        android:functionalTest="false" />

第二个apk中使用Runtime.getRuntime().exec()

1	am instrument -w -m -e debug false com.demo.sample/com.demo.sample.MyInstrumentation

运行结果

Permission Denial: startInstrumentation asks to run as user -2 but is calling from uid u0a164; this requires android.permission.INTERACT_ACROSS_USERS_FULL	
at android.os.Parcel.createException(Parcel.java:2071)	
    at android.os.Parcel.readException(Parcel.java:2039)	
    at android.os.Parcel.readException(Parcel.java:1987)	
    at android.app.IActivityManager$Stub$Proxy.startInstrumentation(IActivityManager.java:5443)
    at com.android.commands.am.Instrument.run(Instrument.java:512)	
    at com.android.commands.am.Am.runInstrument(Am.java:196)	
    at com.android.commands.am.Am.onRun(Am.java:80)	
    at com.android.internal.os.BaseCommand.run(BaseCommand.java:56)
    at com.android.commands.am.Am.main(Am.java:50)	
    at com.android.internal.os.RuntimeInit.nativeFinishInit(Native Method)	
    at com.android.internal.os.RuntimeInit.main(RuntimeInit.java:338)
    Caused by: android.os.RemoteException: Remote stack trace:	
at com.android.server.am.UserController.handleIncomingUser(UserController.java:1683)	
    at com.android.server.am.ActivityManagerService.startInstrumentation(ActivityManagerService.java:15696)
    at android.app.IActivityManager$Stub.onTransact(IActivityManager.java:2350)
    at com.android.server.am.ActivityManagerService.onTransact(ActivityManagerService.java:2738)	
    at android.os.Binder.execTransactInternal(Binder.java:1021)

通过查看代码 userid可以外部传入

1
2
3

if (opt.equals("--user")) {
    instrument.userId = parseUserArg(nextArgRequired());
}

am instrument -w -m --user 0 -e debug false com.demo.sample/com.demo.sample.MyInstrumentation
//或者
app_process -Djava.class.path=/system/framework/am.jar /data/local/tmp com.android.commands.am.Am instrument -w -m --user 0 -e debug false com.demo.sample/com.demo.sample.MyInstrumentation

新的问题又来了

java.lang.RuntimeException: Exception thrown in onCreate() of ComponentInfo{com.demo.sample/com.demo.sample.MyInstrumentation}: java.lang.SecurityException: You do not have android.permission.RETRIEVE_WINDOW_CONTENT required to call registerUiTestAutomationService from pid=14037, uid=10164
        at android.app.ActivityThread.handleBindApplication(ActivityThread.java:6457)
        at android.app.ActivityThread.access$1300(ActivityThread.java:219)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1859)
        at android.os.Handler.dispatchMessage(Handler.java:107)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7356)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)

缺少 android.permission.RETRIEVE_WINDOW_CONTENT权限，但是这个权限是系统应用的，暂时没有想到如果规避这个权限，我这边尝试了很多种方式都绕不过去。

这里解释下为什么必须要用Uiautomator，因为正常的Acc辅助功能需要授权，而Uiautomator中的通过adb shell启动的自动化测试无需授权。

假如一个apk中可以调起另一个apk中的Uiautomator，我们可以想象一个场景，支付宝中有一个instrumentation，里面可以使用uiautomator，高德app中可以调起这个instrumentation，就可以实现模拟用户的行为了。

异常分析：registerUiTestAutomationService

public final class UiAutomationConnection extends IUiAutomationConnection.Stub {
    @Override
    public void connect(IAccessibilityServiceClient client, int flags) {
        if (client == null) {
            throw new IllegalArgumentException("Client cannot be null!");
        }
        synchronized (mLock) {
            throwIfShutdownLocked();
            if (isConnectedLocked()) {
                throw new IllegalStateException("Already connected.");
            }
            mOwningUid = Binder.getCallingUid();
            //这里会进行权限判断 
            registerUiTestAutomationServiceLocked(client, flags);
            storeRotationStateLocked();
        }
    }
}

UiAutomationConnection是在app_process 进程中创建的，而app_process 是另一个apk创建的，这样的情况就是 UiAutomationConnection的group process 是另一个apk；可以尝试启动app_process设置一些参数。adb shell 之所以可以是因为是通过adb shell 创建的app_process

instrumentation 这个可以使用，但是没有应用场景
uiautomator 只能通过adb shell am instrument …调用，否则将有权限问题；因为uiautomator使用了acc辅助权限，当链接AccessibilityService时，无法获取权限，所以脱离adb，无法实现自动模拟操作的行为。

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