androidjunitrunner单元测试执行起来非常慢

我在我的项目中使用了androidjunitrunner,但是在android studio和命令行via中的设备和模拟器上执行单元测试非常缓慢。 gradlew 是的。

我正在使用这个开源项目的主分支onebusaway(截至 this commit )以下内容: https://github.com/OneBusAway/onebusaway-android

我看到所有142个测试的执行时间都超过了3分钟,但android只在“测试结果”下显示的执行时间中注册了一小部分。在切换到androidjunitrunner之前,所有这些单元测试都在20秒内持续执行。

下面是一个示例测试:

/**
 * Tests to evaluate utility methods related to math conversions
 */
@RunWith(AndroidJUnit4.class)
public class MathUtilTest {

    @Test
    public void testOrientationToDirection() {
        // East
        double direction = MathUtils.toDirection(0);
        assertEquals(90.0, direction);
    }
}

这是 build.gradle 配置:

android {
    dexOptions {
        preDexLibraries true
    }
    compileSdkVersion this.ext.compileSdkVersion
    buildToolsVersion "27.0.3"

    defaultConfig {
        minSdkVersion 14
        targetSdkVersion 21
        versionCode 93
        versionName "2.3.8"

        multiDexEnabled true

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

        // The following argument makes the Android Test Orchestrator run its
        // "pm clear" command after each test invocation. This command ensures
        // that the app's state is completely cleared between tests.
        testInstrumentationRunnerArguments clearPackageData: 'true'
    }
    ...
    testOptions {
        execution 'ANDROID_TEST_ORCHESTRATOR'
        unitTests.includeAndroidResources true
    }
...
}
dependencies {
...
    // Unit tests
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestUtil 'com.android.support.test:orchestrator:1.0.2'
...
}

为什么运行单元测试这么慢?