Enable test coverage only when performing CI.

Running test coverage on every single build while developing in the IDE is quite a waste of time.

Author: dbrant

.travis.yml

@@ -28,7 +28,7 @@ before_script:
 - emulator -avd test -no-audio -no-window -no-boot-anim &
 - android-wait-for-emulator
 script:
-- "./gradlew clean check connectedCheck jacocoTestReport"
+- "./gradlew -Pcoverage clean check connectedCheck jacocoTestReport"
 - if [ "$TRAVIS_PULL_REQUEST" == "false" ] && [ "$TRAVIS_BRANCH" == "master" ]; then
   mkdir -p app/src/prodRelease/play/release-notes/en-US;
   fi

app/build.gradle

@@ -139,7 +139,7 @@ android {
         }
         debug {
             minifyEnabled true
-            testCoverageEnabled true
+            testCoverageEnabled project.hasProperty('coverage')
             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
             testProguardFile 'test-proguard-rules.txt'
             versionNameSuffix "-debug-" + getBranchName()