Android Gradle插件报错：The SourceSet 'instrumentTest' is not recognized

升级到Android Studio 3.1，重新构建项目时报错，主要错误为：

The SourceSet 'instrumentTest' is not recognized by the Android Gradle Plugin. Perhaps you misspelled something?

instrumentTest已被废弃，新的Gradle插件已经不支持。instrumentTest需要修改为androidTest。

修改后，sourceSets相关内容类似：

android {
    buildToolsVersion "27.0.3"
    compileSdkVersion 24
    sourceSets {
        main {
            manifest.srcFile 'AndroidManifest.xml'
            java.srcDirs = ['src']
            aidl.srcDirs = ['src']
            renderscript.srcDirs = ['src']
            res.srcDirs = ['res']
            assets.srcDirs = ['assets']
            jniLibs.srcDirs = ['libs']
        }

        androidTest.setRoot('tests')
    }
}