Execution failed for task ':app:preDebugAndroidTestBuild问题解决

as打开新项目时

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.

原因：当我们修改了.build中的compilesdkversion，产生所依赖的dependency与当前版本不一致导致的。

解决办法：build->rebuid-project