annotations' in project ':test'. Resolved versions for app (26.1.0) and test app (27.1.1) differ
报错如下：
Error:Execution failed for task ':test:preDebugAndroidTestBuild'.
> Conflict with dependency 'com.android.support:support-annotations' in project ':test'. Resolved versions for app (26.1.0) and test app (27.1.1) differ. See https://d.android.com/r/tools/test-apk-dependency-conflicts.html for details.
> Conflict with dependency 'com.android.support:support-annotations' in project ':test'. Resolved versions for app (26.1.0) and test app (27.1.1) differ. See https://d.android.com/r/tools/test-apk-dependency-conflicts.html for details.
从以上可以看出这是因为版本不同导致的：
根据我的经验有四种解决办法：
1.可删除所有的测试依赖文件(只能解决当前项目，以后新建项目照样报错)
2.修改版本号为27.1.1
方法三：
在你的module的gradle里面的android括号里面加上下面这段代码：
configurations.all {
resolutionStrategy.force 'com.android.support:support-annotations:27.1.1'
}