title: Conflict with dependency in project ':app'. Resolved versions for app (15.0.2) and test app (12.0.1) differ (possibly onesignal&firebase issue)
body: <p>I cant seem to build gradle for my app on Android Studio 3.0.1 (generate apk works). Below was the build output.</p>
  
  <pre><code>Error:FAILURE: Build failed with an exception.
  
  * What went wrong:
  Execution failed for task ':app:preDebugAndroidTestBuild'.
  &gt; Conflict with dependency 'com.google.firebase:firebase-messaging' in project ':app'. 
  Resolved versions for app (15.0.2) and test app (12.0.1) differ. See https://d.android.com/r/tools/test-apk-dependency-conflicts.html for details.
  
  * Try:
  Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.
  
  * Get more help at https://help.gradle.org
  
  BUILD FAILED in 23s
  </code></pre>
  
  <p><a href="https://gist.github.com/axilaris/3151780bfddc5efbf8f1928d2874230f" rel="nofollow noreferrer">Here</a> is the build.gradle file contents.</p>
  
  <p>UPDATE 21.8.2018:</p>
  
  <p>I notice in the external libraries, I have a conflict</p>
  
  <p><a href="https://i.stack.imgur.com/NEy6X.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/NEy6X.png" alt="enter image description here"></a></p>
  
  <p>I found out that I can generate the apk (Build APK) eventhough gradle produce the conflict error. The way to remove gradle error is to remove/comment this line: </p>
  
  <pre><code>implementation 'com.google.android.gms:play-services-places:15.0.1'
  </code></pre>
  
  <p>but then APK wont compile. It used to work, I realized this problem may have happened after I had to include Firebase in another project (cordova based Android app) that used the same Android Studio. This problem does not happen to my other colleague machine. How do I really solve this ? Thanks </p>