update dependency

Author: vogella

com.vogella.android.daggerjunitmockito/app/build.gradle

@@ -31,19 +31,20 @@ ext {
     supportLibraryVersion = '23.4.0'
     guavaVersion = '18.0'
     glideVersion = '3.6.1'
-    junitVersion = '4.12'
+
     mockitoVersion = '1.10.19'
     powerMockito = '1.6.2'
     hamcrestVersion = '1.3'
     runnerVersion = '0.5'
     rulesVersion = '0.5'
     espressoVersion = '2.2.2'
+    JUNIT_VERSION = '4.12'
     DAGGER_VERSION ='2.4'
 }
 
 dependencies {
     // Dependencies for local unit tests
-    testCompile "junit:junit:$junitVersion"
+    testCompile "junit:junit:$JUNIT_VERSION"
     testCompile "org.mockito:mockito-all:$mockitoVersion"
     testCompile "org.hamcrest:hamcrest-all:$hamcrestVersion"
     testCompile "org.powermock:powermock-module-junit4:$powerMockito"