android自动化测试CTS源码分析之五

6. Instrumentation

6.1 启动Instrumentation

获取adb shell am instrument –w命令后,AM.java中的onRun方法对该命令处理如下

else if (op.equals("instrument")) {            runInstrument();

runInstrument方法如下,

if (!mAm.startInstrumentation(cn, profileFile, 0, args, watcher, connection, userId, abi)) {            throw new AndroidException("INSTRUMENTATION_FAILED: " + cn.flattenToString());        }

调用ActivityManagerService的startInstrumentation方法启动Instrumentation,并且传入相关命令参数。

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");            ProcessRecord app = addAppLocked(ai, false, abiOverride);            app.instrumentationClass = className;            app.instrumentationInfo = ai;            app.instrumentationProfileFile = profileFile;            app.instrumentationArguments = arguments;            app.instrumentationWatcher = watcher;            app.instrumentationUiAutomationConnection = uiAutomationConnection;            app.instrumentationResultClass = className;            Binder.restoreCallingIdentity(origId);

addAppLocked 方法中会调用startProcessLocked方法,到此和Activity等四大组件启动的流程完全一样。

最后在ActivityManagerService的attachApplicationLocked方法中,

Activity的启动主要调用ActivityStackSupervisor的attachApplicationLocked方法,

而Instrumentation的启动主要是调用ApplicationThreadNative的bindApplication方法,

然后跨进程调用ActivityThread的内部类ApplicationThread的bindApplication方法。

ProfilerInfo profilerInfo = profileFile == null ? null                    : new ProfilerInfo(profileFile, profileFd, samplingInterval, profileAutoStop);            thread.bindApplication(processName, appInfo, providers, app.instrumentationClass,                    profilerInfo, app.instrumentationArguments, app.instrumentationWatcher,                    app.instrumentationUiAutomationConnection, testMode, enableOpenGlTrace,                    isRestrictedBackupMode || !normalMode, app.persistent,                    new Configuration(mConfiguration), app.compat,                    getCommonServicesLocked(app.isolated),                    mCoreSettingsObserver.getCoreSettingsLocked());            updateLruProcessLocked(app, false, null);            app.lastRequestedGc = app.lastLowMemory = SystemClock.uptimeMillis();

当然,启动Instrumentation的过程中也会创建进程。

ActivityThread的内部类ApplicationThread的bindApplication方法部分代码如下,

AppBindData data = new AppBindData();            data.processName = processName;            data.appInfo = appInfo;            data.providers = providers;            data.instrumentationName = instrumentationName;            data.instrumentationArgs = instrumentationArgs;            data.instrumentationWatcher = instrumentationWatcher;            data.instrumentationUiAutomationConnection = instrumentationUiConnection;            data.debugMode = debugMode;            data.enableOpenGlTrace = enableOpenGlTrace;            data.restrictedBackupMode = isRestrictedBackupMode;            data.persistent = persistent;            data.config = config;            data.compatInfo = compatInfo;            data.initProfilerInfo = profilerInfo;            sendMessage(H.BIND_APPLICATION, data);

主要时发送handler消息切换到主线程执行。

Handler对BIND_APPLICATION消息处理如下,

AppBindData data = (AppBindData)msg.obj;handleBindApplication(data);

handleBindApplication方法中有关instrumentation代码如下,

首先利用发射构造instrumentation对象,

try {                java.lang.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);            }

然后调用instrumentation对象的init方法。

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

最后调用instrumentation对象的onCreate方法。

mInstrumentation.onCreate(data.instrumentationArgs);

6.2 Instrumentation作用

Instrumentation在自动化测试中主要作用是什么呢?

简单点说,进行自动化测试时,很多时候并不需要界面。因此可以这么说,在自动化测试中,Instrumentation作用相当于Activity。

其中的方法几乎和Activity对应的方法一摸一样。例如，

public void onCreate(Bundle arguments) {}public void onStart() { }public void onDestroy() { }

CTS的蓝牙apk的AndroidManifest.xml文件如下,

<manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="com.android.cts.bluetooth">    <uses-permission android:name="android.permission.BLUETOOTH" />    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />    <uses-permission android:name="android.permission.DISABLE_KEYGUARD" />    <application>        <uses-library android:name="android.test.runner" />    </application>    <!-- This is a self-instrumenting test package. -->    <instrumentation android:name="android.support.test.runner.AndroidJUnitRunner"                     android:targetPackage="com.android.cts.bluetooth"                     android:label="CTS tests of bluetooth component">        <meta-data android:name="listener"            android:value="com.android.cts.runner.CtsTestRunListener" />    </instrumentation></manifest>

也只是将instrumentation替换了activity.

AndroidJUnitRunner和InstrumentationTestRunner都是继承于Instrumentation,作用大同小异,

但是测试原理完全一样，因此本文选择InstrumentationTestRunner进行分析。

InstrumentationTestRunner扮演的角色类似于当中的UiAutomatorTestRunner类，

通过解析获取和建立目标测试用例和测试集然后开始测试。

onCreate方法调用流程图如下,

InstrumentationTestRunner的onStart方法如下,

try {                 //新建打印结果对象                StringResultPrinter resultPrinter = new StringResultPrinter(writer);                  //设置测试监听                mTestRunner.addTestListener(resultPrinter);                   // 获取开始的系统时间                long startTime = System.currentTimeMillis();                  // 开始进行测试                mTestRunner.runTest();                   // 测试时间                long runTime = System.currentTimeMillis() - startTime;                   // 打印测试结果                resultPrinter.printResult(mTestRunner.getTestResult(), runTime);            } catch (Throwable t) {                // catch all exceptions so a more verbose error message can be outputted                writer.println(String.format("Test run aborted due to unexpected exception: %s",                                t.getMessage()));                t.printStackTrace(writer);            } finally {                mResults.putString(Instrumentation.REPORT_KEY_STREAMRESULT,                        String.format("\nTest results for %s=%s",                        mTestRunner.getTestClassName(),                        byteArrayOutputStream.toString()));                if (mCoverage) {                    generateCoverageReport();                }                writer.close();                   // 调用finish方法                finish(Activity.RESULT_OK, mResults);             }        }

6.3,测试

在InstrumentationTestRunner的onStart方法中会调用AndroidTestRunner的runTest进行测试, runTest方法如下,

public void runTest(TestResult testResult) {        mTestResult = testResult;         for (TestListener testListener : mTestListeners) {            mTestResult.addListener(testListener);        }        Context testContext = mInstrumentation == null ? mContext : mInstrumentation.getContext();        for (TestCase testCase : mTestCases) {            setContextIfAndroidTestCase(testCase, mContext, testContext);            setInstrumentationIfInstrumentationTestCase(testCase, mInstrumentation);            setPerformanceWriterIfPerformanceCollectorTestCase(testCase, mPerfWriter);            testCase.run(mTestResult);        }    }

首先设置监听,然后逐个调用测试方法。

CTS测试中,每个apk测试的TestCase完全不一样,一般都继承于AndroidTestCase,而AndroidTestCase继承于TestCase。

以蓝牙测试为例,测试类BasicAdapterTest定义如下,

public class BasicAdapterTest extends AndroidTestCase {

该测试类有8个以test开头的测试用例。

具体的调用过程就不论述了,

TestCase的runBare方法如下,

public void runBare() throws Throwable {Throwable exception= null;setUp();try {runTest();} catch (Throwable running) {exception= running;}finally {try {tearDown();} catch (Throwable tearingDown) {if (exception == null) exception= tearingDown;}}if (exception != null) throw exception;}

1,在测试之前会调用setUp方法。

2,利用反射的方法进行测试用例的调用。

3,测试完成之后,会调用tearDown方法。

至于具体的测试用例,可以看蓝牙的测试。