为什么要重载operator（）？(Why override operator()?)

 正如 Google团队的工程师（最有可能是Xavier Ducrohet ） 所提到的，Robolectric在AAPT2方面存在问题： 
 
 
 
 Robolectric与aapt2不兼容。 
 
 
 这里有两个选项。 
 
 第一个选项 - 遵循Android Studio 3.0+的 Robolectric 指南 
 
 
 
 将以下内容添加到您的build.gradle中： 
 
 
android {
  testOptions {
    unitTests {
      includeAndroidResources = true
    }
  }
}
 
 
 
 用Robolectric测试跑步者注释你的测试： 
 
 
@RunWith(RobolectricTestRunner.class)
public class SandwichTest {
}
 
 
 第二个选项：禁用AAPT2将以下行添加到gradle.properties文件中： 
 
android.enableAapt2=false

As mentioned by an engineer from Google team (most possibly Xavier Ducrohet), Robolectric has issues with AAPT2:
 
 
 
Robolectric is not compatible with aapt2.
 
 
Two options here.
 
First option - follow Robolectric guidelines for Android Studio 3.0+
 
 
 
Add the following to your build.gradle:
 
 
android {
  testOptions {
    unitTests {
      includeAndroidResources = true
    }
  }
}
 
 
 
Annotate your test with the Robolectric test runner:
 
 
@RunWith(RobolectricTestRunner.class)
public class SandwichTest {
}
 
 
Second option: disable AAPT2 adding following line into gradle.properties file:
 
android.enableAapt2=false