在AVD仿真器上運行Gradle connectedCheck時出現NoClassDefFoundError

Question

我正在嘗試為Android應用運行Espresso測試。 它在硬件設備上運行良好。 當我在新創建的AVD模擬器上運行它時，它會失敗 ，如下所示：

:ExampleApp:connectedDebugAndroidTest

com.example.MainFragmentTest > initializationError[Nexus_5_API_19(AVD) - 4.4.2] 
FAILED 
    java.lang.NoClassDefFoundError: com/example/MainActivity
    at java.lang.Class.getDeclaredFields(Native Method)
:ExampleApp:connectedDebugAndroidTest FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':ExampleApp:connectedDebugAndroidTest'.
> There were failing tests. See the report at: 
file:///home/user/work/ExampleApp/build/reports/androidTests/connected/index.html

HTML報告包含以下堆棧跟蹤：

java.lang.NoClassDefFoundError: com/example/MainActivity
at java.lang.Class.getDeclaredFields(Native Method)
at java.lang.Class.getDeclaredFields(Class.java:610)
at org.junit.runners.model.TestClass.getSortedDeclaredFields(TestClass.java:77)
at org.junit.runners.model.TestClass.scanAnnotatedMembers(TestClass.java:70)
at org.junit.runners.model.TestClass.<init>(TestClass.java:57)
at org.junit.runners.ParentRunner.createTestClass(ParentRunner.java:88)
at org.junit.runners.ParentRunner.<init>(ParentRunner.java:83)
at org.junit.runners.BlockJUnit4ClassRunner.<init>(BlockJUnit4ClassRunner.java:65)
at android.support.test.internal.runner.junit4.AndroidJUnit4ClassRunner.<init>(AndroidJUnit4ClassRunner.java:38)
at android.support.test.runner.AndroidJUnit4.<init>(AndroidJUnit4.java:36)
at java.lang.reflect.Constructor.constructNative(Native Method)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at android.support.test.internal.runner.junit4.AndroidAnnotatedBuilder.buildAndroidRunner(AndroidAnnotatedBuilder.java:57)
at android.support.test.internal.runner.junit4.AndroidAnnotatedBuilder.runnerForClass(AndroidAnnotatedBuilder.java:45)
at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:59)
at org.junit.internal.builders.AllDefaultPossibilitiesBuilder.runnerForClass(AllDefaultPossibilitiesBuilder.java:26)
at org.junit.runner.Computer.getRunner(Computer.java:40)
at org.junit.runner.Computer$1.runnerForClass(Computer.java:31)
at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:59)
at org.junit.runners.model.RunnerBuilder.runners(RunnerBuilder.java:101)
at org.junit.runners.model.RunnerBuilder.runners(RunnerBuilder.java:87)
at org.junit.runners.Suite.<init>(Suite.java:81)
at org.junit.runner.Computer.getSuite(Computer.java:28)
at android.support.test.internal.runner.TestRequestBuilder.classes(TestRequestBuilder.java:701)
at android.support.test.internal.runner.TestRequestBuilder.build(TestRequestBuilder.java:664)
at android.support.test.runner.AndroidJUnitRunner.buildRequest(AndroidJUnitRunner.java:329)
at android.support.test.runner.AndroidJUnitRunner.onStart(AndroidJUnitRunner.java:226)
at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:1701)

Caused by: java.lang.ClassNotFoundException: Didn't find class 
  "com.example.MainActivity" on path: DexPathList[[zip file 
  "/system/framework/android.test.runner.jar", zip file 
  "/data/app/com.example.debug.test-1.apk", zip file 
  "/data/app/com.example.debug-1.apk"],
  nativeLibraryDirectories=[/data/app-lib/com.example.debug.test-1, 
  /data/app-lib/com.example.debug-1, /vendor/lib, /system/lib]]
at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
at java.lang.ClassLoader.loadClass(ClassLoader.java:497)
at java.lang.ClassLoader.loadClass(ClassLoader.java:457)
... 28 more

我基本上遵循espresso / BasicSample / ChangeTextBehaviorTest.java中的結構。 此測試適用於模擬器！

對於我的測試，我可以把它歸結為當我使用以下代碼時運行測試已經失敗 ：

@RunWith(AndroidJUnit4.class)
public class MainFragmentTest {

    @Rule
    public ActivityTestRule<MainActivity> mActivityRule = 
        new ActivityTestRule<>(MainActivity.class);    
}

這是完整的測試類：

import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.junit.runner.RunWith;

import android.support.test.rule.ActivityTestRule;
import android.support.test.runner.AndroidJUnit4;

import com.example.R;

import static android.support.test.espresso.Espresso.onView;
import static android.support.test.espresso.assertion.ViewAssertions.matches;
import static android.support.test.espresso.matcher.ViewMatchers.withId;
import static android.support.test.espresso.matcher.ViewMatchers.withText;

@RunWith(AndroidJUnit4.class)
public class MainFragmentTest {

    @Rule
    public ActivityTestRule<MainActivity> mActivityRule = 
        new ActivityTestRule<>(MainActivity.class);

    MainActivity mMainActivity;

    MainFragment mMainFragment;

    @Before
    public void setUp() {
        mMainActivity = mActivityRule.getActivity();
        mMainFragment = (MainFragment) mMainActivity
                .getSupportFragmentManager()
                .findFragmentByTag(MainFragment.FRAGMENT_TAG);
    }

    @Test
    public void testHeadline() {
        onView(withId(R.id.headline)).check(matches(withText(R.string.headline)));
    }
}

我目前正在使用以下工具鏈：

• com.android.tools.build:gradle:1.4.0-beta2
• buildToolsVersion“23.0.1”
• compileSdkVersion 22
• targetSdkVersion 22
• Gradle包裝2.5
• java版“1.7.0_79”OpenJDK

Answer 1

經過一些試驗和錯誤后，我通過這個調整得到了我的運行：

androidTestCompile 'com.android.support.test.espresso:espresso-contrib:2.2.1'

改成

androidTestCompile('com.android.support.test.espresso:espresso-contrib:2.2') {
    exclude group: 'com.android.support', module: 'support-v4'
}

不知何故，espresso-contrib中包含的東西阻止了正確版本的support-v4被包含在測試包中，並導致類加載器失敗。

Answer 2

經過一些試驗和錯誤后，我意識到特定AVD仿真器發生錯誤，而其他測試執行成功。 我在問題中沒有提到的一個重要的附注是我使用Google Play服務運行測試的應用程序。 因此，我需要選擇提供框架的模擬器。

測試運行成功：

• Android 6.0（API 23）Google API Intel x86 Atom System Image
• Android 5.1.1（API 22）Google API Intel x86 Atom System Image

測試失敗：

• Android 4.4.2（API 19）Google API（x86系統映像）

未知/其他錯誤：

• Android 5.1.1（API 22）Google API Intel x86 Atom_64系統映像
  由於問題＃180674中描述的錯誤，我無法在此AVD上安裝APK。

Answer 3

作為安裝問題的解決方法，您還可以手動運行檢測：

1.生成目標和測試apk

gradle connectedAndroidTest

它將無法安裝apk，但仍然會將它們生成為輸出。

2.手動安裝test＆target apk

adb install XXX-debug-androidTest-unaligned.apk

adb install XXX-debug.apk

3.手動觸發入侵

adb shell am instrument -w -e your.package.test/.common.Instrumentation

這將顯示所有已安裝的儀器：

adb shell pm list instrumentation

有關更多信息，請查看官方儀器文檔 。