android - java.lang.Exception : Custom runner class AndroidJUnit4 should have a public constructor with signature AndroidJUnit4(Class testClass)

Question

gradle 看起来像:

apply plugin: 'com.android.application'

android {
    compileSdkVersion 25
    buildToolsVersion "25.0.2"

    defaultConfig {
        applicationId "com.google.developer.taskmaker"
        minSdkVersion 19
        targetSdkVersion 25
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

configurations.all {
    resolutionStrategy {
        force 'com.android.support:support-annotations:25.2.0'
    }
}


dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:25.2.0'
    compile 'com.android.support:recyclerview-v7:25.2.0'
    compile 'com.android.support:design:25.2.0'
    compile 'com.android.support:preference-v7:25.2.0'
    debugCompile 'im.dino:dbinspector:3.4.1@aar'
    // Android JUnit Runner
    compile 'com.google.android.gms:play-services-appindexing:8.4.0'
    // Android runner and rules support

    // add this for intent mocking support
    androidTestCompile 'com.android.support.test.espresso:espresso-intents:2.2.2'

    // add this for webview testing support
    androidTestCompile 'com.android.support.test.espresso:espresso-web:2.2.2'
    compile 'com.android.support.test:runner:0.5'
    compile 'com.android.support.test:rules:0.5'
    compile 'com.android.support.test.espresso:espresso-core:2.2.2'
}

单元测试用例的样子

@RunWith(AndroidJUnit4.class)
public class TestClass {

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

    @Test
    public void buttonClick(){
        onView(withId(R.id.fab)).perform(click()).check(matches(isDisplayed()));
    }

}

错误信息如下:

java.lang.Exception: Custom runner class AndroidJUnit4 should have a public constructor with signature AndroidJUnit4(Class testClass)

    at org.junit.runners.model.InitializationError.<init>(InitializationError.java:38)
    at org.junit.internal.builders.AnnotatedBuilder.buildRunner(AnnotatedBuilder.java:111)
    at org.junit.internal.builders.AnnotatedBuilder.runnerForClass(AnnotatedBuilder.java:86)
    at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:59)
    at org.junit.internal.builders.AllDefaultPossibilitiesBuilder.runnerForClass(AllDefaultPossibilitiesBuilder.java:26)
    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 com.intellij.junit4.JUnit46ClassesRequestBuilder.collectWrappedRunners(JUnit46ClassesRequestBuilder.java:90)
    at com.intellij.junit4.JUnit46ClassesRequestBuilder.getClassesRequest(JUnit46ClassesRequestBuilder.java:51)
    at com.intellij.junit4.JUnit4TestRunnerUtil.buildRequest(JUnit4TestRunnerUtil.java:91)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:95)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:42)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:234)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:74)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:497)
    at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)


Process finished with exit code -1

我已经检查了其他答案，但没有得到解决方案。请告诉问题出在哪里。运行此代码时出现错误

Answer 1

原因 1:将测试放在错误的文件夹中

可以通过在 Android Studio 中使用默认模板创建一个新应用程序并复制自动生成的 ExampleInstrumentedTest 来复制此错误。来自 androidTest文件夹到 test文件夹:

这是错误的样子:

请注意，为了重现问题，您还必须错误地将依赖项添加到模块级别 build.gradle :

原因2:测试配置错误

本地单元测试和插装测试具有不同的运行配置。如果您单击 Edit Configurations，如下所示:

您应该在 Android Instrumented Tests 下看到您的仪器测试以及 Android JUnit 下的本地单元测试如下图所示:

对于 Android Instrumented 测试，配置应如下所示:

对于 Android JUnit:

当您运行测试时，Android Studio 会为您创建一个运行配置。如果运行配置属于错误类别，请检查您的 test和 androidTest文件夹正确，然后您可以从 Edit configurations 中删除运行配置并再次运行测试。如果设置正确，Android Studio 这次会使用正确类型的运行配置。

说明

Android 中有两种类型的测试:

1. 仪器测试
2. 本地单元测试

仪器测试

仪器测试是设计用于在手机或模拟器上运行的测试。在这些测试中，您需要访问 Android 库的完整功能部分(例如真实的 Context)。这些需要进入androidTest这些测试的文件夹和依赖项(例如，Espresso、com.android.support.test.rules:0.5)将以 androidTestCompile 为前缀在您的build.gradle .

这是一个仪器测试示例:

import android.content.Context;
import android.support.test.InstrumentationRegistry;
import android.support.test.runner.AndroidJUnit4;

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

import static org.junit.Assert.assertEquals;

/**
 * Instrumentation test, which will execute on an Android device.
 *
 * @see <a href="http://d.android.com/tools/testing">Testing documentation</a>
 */
@RunWith(AndroidJUnit4.class)
public class ExampleInstrumentedTest {
    @Test
    public void useAppContext() throws Exception {
        // Context of the app under test.
        Context appContext = InstrumentationRegistry.getTargetContext();

        assertEquals("com.gyaltsab.myapplication", appContext.getPackageName());
    }
}

本地单元测试

本地单元测试是您可以在您的 IDE 中运行的测试。它们通常不依赖于标准 JVM 上不可用的 Android 库的任何部分(例如，它们不依赖于 Context )。这些依赖项位于 testCompile您的 build.gradle 的一部分.

这是一个示例单元测试:

import org.junit.Test;

import static org.junit.Assert.*;

/**
 * Example local unit test, which will execute on the development machine (host).
 *
 * @see <a href="http://d.android.com/tools/testing">Testing documentation</a>
 */
public class ExampleUnitTest {
    @Test
    public void addition_isCorrect() throws Exception {
        assertEquals(4, 2 + 2);
    }
}

请注意，本地单元测试不需要 @RunWith(AndroidJUnit4.class)类声明中的注释。请看 the official docs以获得更完整的解释。