Android新的库模块执行默认的单元测试，但出现错误“找不到类：ExampleUnitTest”

Question

build.gradle文件：

apply plugin: 'com.android.library'

android {
    compileSdkVersion 28


    defaultConfig {
        minSdkVersion 19
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"

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

    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }

}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])

    implementation 'com.android.support:appcompat-v7:28.0.0'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2' }

  

未完成退出代码为1的类的过程：   “ com.sample.ktg.ExampleUnitTest”