Android儀表單元測試中的上下文和資源

Question

我正在設計一個系統，其中包含一些不太簡單的類，需要Context對象才能初始化它們。 這些類使用第三方類，這些類也需要上下文初始化。 此類還利用上下文來加載功能所需的許多字符串資源。

問題在於為這些類編寫Instrumented Unit測試。 當我嘗試使用InstrumentationRegistry.getContext（）為測試獲取Context對象時，我遇到了一個異常，其中上下文找不到與該類關聯的字符串資源（android.content.res.Resources $ NotFoundException）。

我的問題是：我如何設計這些測試，以便上下文可以檢索我需要的字符串資源，還可以作為第三方類的合適上下文對象？ 我只能做很多嘲弄，因為其中一些類處理auth令牌，這很難模仿。 我不可能是唯一一個在Android域中遇到此問題的人，所以我確信這個可能是常見問題的解決方案。

編輯：正如所建議的，我已經嘗試在我的項目中集成Robolectric（版本3.3.2），但是當我嘗試運行我的單元測試時，我遇到了以下錯誤：

Error:Error converting bytecode to dex:
Cause: Dex cannot parse version 52 byte code.
This is caused by library dependencies that have been compiled using Java 8 or above.
If you are using the 'java' gradle plugin in a library submodule add 
targetCompatibility = '1.7'
sourceCompatibility = '1.7'
to that submodule's build.gradle file. 

我嘗試將targetCompatibility和sourceCompatibility行添加到我的gradle文件（在幾個位置）無濟於事。

這是我的移動build.gradle：

apply plugin: 'com.android.application'
apply plugin: 'checkstyle'
apply plugin: 'io.fabric'

project.ext {
    supportLibVersion = '25.3.0'
    multiDexSupportVersion = '1.0.1'
    gsonVersion = '2.8.0'
    retrofitVersion = '2.2.0'
    daggerVersion = '2.4'
    butterKnifeVersion = '8.5.1'
    eventBusVersion = '3.0.0'
    awsCoreServicesVersion = '2.2.+'
    twitterKitVersion = '2.3.2@aar'
    facebookVersion = '4.+'
    crashlyticsVersion = '2.6.7@aar'
    autoValueVersion = '1.2'
    autoValueParcelVersion = '0.2.5'
    autoValueGsonVersion = '0.4.4'
    permissionDispatcher = '2.2.0'
    testRunnerVersion = '0.5'
    espressoVersion = '2.2.2'
    junitVersion = '4.12'
    roboelectricVersion = '3.3.2'
}

def gitSha = exec('git rev-parse --short HEAD', "unknown");
def gitCommitCount = 100 + Integer.parseInt(exec('git rev-list --count HEAD', "-1"))
def gitTag = exec('git describe --tags', stringify(gitCommitCount))
def gitTimestamp = exec('git log -n 1 --format=%at', -1)

def appId = "com.example.myapp"
def isCi = "true".equals(System.getenv("CI"))

// Uncomment if you wish to enable Jack & Java8
// apply from: 'jack.gradle'

// Uncomment if you wish to enable Sonar
//apply from: 'sonar.gradle'

android {
  compileSdkVersion 25
  buildToolsVersion "25.0.2"

  defaultConfig {
    applicationId appId
    minSdkVersion 16
    targetSdkVersion 25

      multiDexEnabled = true

    versionCode gitCommitCount
    versionName gitTag

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

    buildConfigField 'String', 'GIT_SHA', "\"${gitSha}\""
    buildConfigField 'long', 'GIT_TIMESTAMP', "${gitTimestamp}L"
  }

  buildTypes {
    debug {
      applicationIdSuffix '.debug'
    }
    release {
      minifyEnabled true
      proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
    }
    qa.initWith(buildTypes.release)
    qa {
      applicationIdSuffix '.qa'
      debuggable true
    }
  }

  lintOptions {
    abortOnError false
  }

  applicationVariants.all { variant ->
    def strictMode = !variant.name.equals("release")
    buildConfigField 'boolean', 'STRICT_MODE_ENABLED', "${strictMode}"
  }
}

configurations.all {
  resolutionStrategy {
    force "com.android.support:support-annotations:$supportLibVersion"
    force "com.squareup.okhttp3:okhttp:3.4.1"
    force "com.squareup:okio:1.9.0"
    force "com.google.guava:guava:19.0"
  }
}

dependencies {
    compile "com.android.support:appcompat-v7:$supportLibVersion"
    compile "com.android.support:design:$supportLibVersion"
    compile "com.android.support:recyclerview-v7:$supportLibVersion"
    compile "com.android.support:cardview-v7:$supportLibVersion"
    compile "com.android.support:multidex:$multiDexSupportVersion"

    compile "com.squareup.retrofit2:retrofit:$retrofitVersion"
    compile "com.squareup.retrofit2:converter-gson:$retrofitVersion"
    compile 'com.jakewharton.retrofit:retrofit2-rxjava2-adapter:1.0.0'

    compile "com.google.dagger:dagger:$daggerVersion"
    annotationProcessor "com.google.dagger:dagger-compiler:$daggerVersion"
    provided 'javax.annotation:jsr250-api:1.0'

    compile 'com.github.bumptech.glide:glide:3.7.0'
    compile 'com.jakewharton.timber:timber:4.3.1'
    compile "com.jakewharton:butterknife:$butterKnifeVersion"
    annotationProcessor "com.jakewharton:butterknife-compiler:$butterKnifeVersion"

    compile "org.greenrobot:eventbus:$eventBusVersion"
    annotationProcessor "org.greenrobot:eventbus:$eventBusVersion"

    compile 'io.reactivex.rxjava2:rxandroid:2.0.0'
    debugCompile 'com.squareup.okhttp3:logging-interceptor:3.4.2'

    compile "com.google.auto.value:auto-value:$autoValueVersion"
    annotationProcessor "com.google.auto.value:auto-value:$autoValueVersion"

    compile "com.ryanharter.auto.value:auto-value-parcel-adapter:$autoValueParcelVersion"
    annotationProcessor "com.ryanharter.auto.value:auto-value-parcel:$autoValueParcelVersion"

    compile "com.github.hotchemi:permissionsdispatcher:$permissionDispatcher"
    annotationProcessor "com.github.hotchemi:permissionsdispatcher-processor:$permissionDispatcher"

    compile("com.crashlytics.sdk.android:crashlytics:$crashlyticsVersion") {
        transitive = true;
    }

    compile("com.twitter.sdk.android:twitter:$twitterKitVersion") {
        transitive = true
    }

    compile "com.facebook.android:facebook-android-sdk:$facebookVersion"

    compile "com.amazonaws:aws-android-sdk-core:$awsCoreServicesVersion"
    annotationProcessor "com.amazonaws:aws-android-sdk-core:$awsCoreServicesVersion"
    compile "com.amazonaws:aws-android-sdk-apigateway-core:$awsCoreServicesVersion"
    annotationProcessor "com.amazonaws:aws-android-sdk-apigateway-core:$awsCoreServicesVersion"
    compile "com.amazonaws:aws-android-sdk-cognito:$awsCoreServicesVersion"
    annotationProcessor "com.amazonaws:aws-android-sdk-cognito:$awsCoreServicesVersion"
    compile "com.amazonaws:aws-android-sdk-cognitoidentityprovider:$awsCoreServicesVersion"
    annotationProcessor "com.amazonaws:aws-android-sdk-cognitoidentityprovider:$awsCoreServicesVersion"
    compile "com.amazonaws:aws-android-sdk-lambda:$awsCoreServicesVersion"
    annotationProcessor "com.amazonaws:aws-android-sdk-lambda:$awsCoreServicesVersion"
    compile "com.amazonaws:aws-android-sdk-sns:$awsCoreServicesVersion"
    annotationProcessor "com.amazonaws:aws-android-sdk-sns:$awsCoreServicesVersion"

    androidTestCompile "junit:junit:$junitVersion"
    androidTestCompile "com.android.support.test:runner:$testRunnerVersion"
    androidTestCompile "com.android.support.test:rules:$testRunnerVersion"
    androidTestCompile "com.android.support.test.espresso:espresso-intents:$espressoVersion"
    androidTestCompile "com.android.support.test.espresso:espresso-core:$espressoVersion"
    androidTestCompile "com.squareup.retrofit2:retrofit-mock:$retrofitVersion"
    androidTestCompile "org.robolectric:robolectric:$roboelectricVersion"

    testCompile "junit:junit:$junitVersion"
    testCompile 'com.google.truth:truth:0.30'
    testCompile 'org.hamcrest:hamcrest-all:1.3'
    testCompile "org.robolectric:robolectric:$roboelectricVersion"
}

task checkCodingStyle(type: Checkstyle) {
  description 'Runs Checkstyle inspection against Android sourcesets.'
  group = 'Code Quality'
  ignoreFailures = false
  showViolations = false
  source 'src'
  include '**/*.java'
  exclude '**/gen/**'
  exclude '**/R.java'
  exclude '**/BuildConfig.java'
  reports {
    xml.destination "$project.buildDir/reports/checkstyle/report.xml"
  }
  classpath = files()
  configFile = file("${rootProject.rootDir}/config/checkstyle/checkstyle.xml")
}

def stringify(int versionCode) {
  def builder = new StringBuilder();
  def dot = ""
  String.format("%03d", versionCode).toCharArray().each {
    builder.append(dot)
    builder.append(it)
    dot = "."
  }
  return builder.toString()
}

def exec(String command, Object fallback = null) {
  def cmd = command.execute([], project.rootDir)
  cmd.waitFor()
  if (cmd.exitValue() != 0) {
    if (fallback == null) {
      throw new RuntimeException("'$command' failed: $cmd.errorStream.text")
    } else {
      return fallback
    }
  }
  return cmd.text.trim()
}

if (isCi) {
  build.finalizedBy(checkCodingStyle)
}

Answer 1

接受的答案不是實際的解決方案。 在許多情況下，您希望測試與真實Android框架的交互。 與任何其他存根一樣，Robolectric可能會隱藏一些實際問題。

您的問題是您使用的InstrumentationRegistry.getContext()與您的應用程序使用的不同。 根據文件：

返回此檢測包的Context。

你應該使用InstrumentationRegistry.getTargetContext()代替：

返回正在檢測的目標應用程序的上下文。

因為它與第一個相反，可以訪問您的資源。

Answer 2

Robolectric可能是解決您問題的方法。 它允許您在test文件夾中編寫單元測試（注意： androidTest文件夾中沒有檢測的單元測試），這些單元測試利用Context訪問所有R.string.*資源。

這是一個例子：

@RunWith(RobolectricTestRunner.class)
public class FooTest {

    private final Contet context;

    @Before
    public void setup() {
        context = RuntimeEnvironment.application;
    }

    public void testMyStringResource() {
        String mySpecialString = context.getString(R.string.mySpecialString);
        assertEquals("special", mySpecialString);
    }
}

更新：

您從Robolectric獲得的錯誤消息是由將依賴項作為androidTestCompile而不是testCompile