NoClassDefFoundError：org / json / JSONException - 带有gradle的Android Robolectric

Question

我的Android gradle和robolectric单元测试运行正常，直到我必须为使用JSONException或org.json包中的任何内容的类编写单元测试。

apply plugin: 'android'
apply plugin: 'com.android.application'
apply plugin: 'robolectric'
apply plugin: 'crashlytics'
apply plugin: 'jacoco' //provides code coverage metrics

dependencies {
    // regular dependences
    ...


    // unit testing
    androidTestCompile fileTree(dir: 'libs/test', include: '*.jar')
    androidTestCompile('com.squareup:fest-android:1.0.+') {
        exclude group: 'com.android.support'
    }
    androidTestCompile 'com.google.dexmaker:dexmaker:1.+'

    androidTestCompile('junit:junit:4.11') {
        exclude module: 'hamcrest-core'
    }
    androidTestCompile 'org.hamcrest:hamcrest-library:1.3'
    androidTestCompile 'org.mockito:mockito-core:1.9.5'
    androidTestCompile('org.robolectric:robolectric:2.4') {
        exclude module: 'classworlds'
        exclude module: 'commons-logging'
        exclude module: 'httpclient'
        exclude module: 'maven-artifact'
        exclude module: 'maven-artifact-manager'
        exclude module: 'maven-error-diagnostics'
        exclude module: 'maven-model'
        exclude module: 'maven-project'
        exclude module: 'maven-settings'
        exclude module: 'plexus-container-default'
        exclude module: 'plexus-interpolation'
        exclude module: 'plexus-utils'
        exclude module: 'wagon-file'
        exclude module: 'wagon-http-lightweight'
        exclude module: 'wagon-provider-api'
    }
}

我得到的例外情况如下，这很奇怪，因为所有构建都很好。任何的想法？我对robolectric的排除是否有所帮助？

java.lang.NoClassDefFoundError: org/json/JSONException
    at java.lang.Class.getDeclaredConstructors0(Native Method)
    at java.lang.Class.privateGetDeclaredConstructors(Class.java:2585)
    at java.lang.Class.getConstructors(Class.java:1522)
    at org.junit.runners.model.TestClass.<init>(TestClass.java:39)
    at org.junit.runners.ParentRunner.<init>(ParentRunner.java:75)
    at org.junit.runners.BlockJUnit4ClassRunner.<init>(BlockJUnit4ClassRunner.java:57)
    at org.robolectric.RobolectricTestRunner.<init>(RobolectricTestRunner.java:62)
    ...

我知道为什么会碰到这个？