Android 的单元测试有两种方式：JUnit test(本地虚拟机测试) 和 instrumented test(设备测试)。

a JUnit test that runs on the local JVM or an instrumented test that runs on a device

Local unit tests：Located at module-name/src/test/java/ 可以本地虚拟机测试，只能调用Java API ，不能调用 Android API 。不过，可以通过依赖 android.jar 或者 第三方库(如：Mockito)调用 Android API。

Instrumented tests：Located at module-name/src/androidTest/java/ 在设备上运行，可以调试Android API，并可自定义测试配置文件。通过依赖第三方库(如：Espresso)可以实现 UI testing.

二、环境配置

the test library dependencies in your app module's build.gradle file:

dependencies {

// Required for local unit tests (JUnit 4 framework)

testCompile 'junit:junit:4.12'

// Required for instrumented tests

androidTestCompile 'com.android.support:support-annotations:24.0.0'

androidTestCompile 'com.android.support.test:runner:0.5'

}

单元测试在项目中的目录结构：

Paste_Image.png

配置问题：

Conflict with dependency 'com.android.support:support-annotations'. Resolved versions for app (23.3.0) and test app (23.1.1) differ

解决方案 :参考官网

To use JUnit 4 test classes, make sure to specify AndroidJUnitRunner as the default test instrumentation runner in your project by including the following setting in your app's module-level build.gradle file:

android {

defaultConfig {

testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"

}

}

上面是配置，然后添加下面这句：

android{

configurations.all {

resolutionStrategy.force 'com.android.support:support-annotations:23.1.0'

}

}

三、创建 Test 文件

import org.junit.Test;

import java.util.regex.Pattern;

import static org.junit.Assert.assertFalse;

import static org.junit.Assert.assertTrue;

public class EmailValidatorTest {

@Test

public void emailValidator_CorrectEmailSimple_ReturnsTrue() {

assertThat(EmailValidator.isValidEmail("name@email.com"), is(true));

}

...}

import org.junit.Before;import org.junit.Test;

import org.junit.runner.RunWith;

/**

* RxJava simple test

* Created by ys on 2016/10/14 0014.

*/

@RunWith(AndroidJUnit4.class)

@SmallTest

public class RxJavaSimpleTest {

private RxJavaSimple mRxJavaSimple;

@Before

public void createRxJavaSimple(){

mRxJavaSimple = new RxJavaSimple();

}

@Test

public void testScheduler(){

//打印 Log

mRxJavaSimple.testScheduler();

}

}

四、Run Test

To run your instrumented tests, follow these steps:

Be sure your project is synchronized with Gradle by clicking Sync Project

in the toolbar.

Run your test in one of the following ways:

To run a single test, open the Project window, and then right-click a test and click Run

.

To test all methods in a class, right-click a class or method in the test file and click Run

.

To run all tests in a directory, right-click on the directory and select Run tests

三种方式：

运行单个 Test，右键 -> Run。

运行单个Test 文件，右键 class -> Run。

运行文件夹中所有Test，右键文件夹-> Run tests。