Error:Execution failed for task ':app:preDebugAndroidTestBuild'.
今天运行项目的时候直接报了个这个错误，我也没干别的啊
Error:Execution failed for task ‘:app:preDebugAndroidTestBuild’.
Conflict with dependency ‘com.android.support:support-annotations’ in project ‘:app’. 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.
解决办法：
点击菜单栏Build—>RebuildProject
重新加载一下，再点击运行，就搞定了！
感谢原文作者