Made the tests in MainPresenter be more specific & made the RandomBookGenerator methods not static to make it mockable.

app/build.gradle

@@ -27,6 +27,8 @@ android {
 dependencies {
     compile fileTree(dir: 'libs', include: ['*.jar'])
 
+    androidTestCompile 'org.mockito:mockito-core:2.5.5'
+    androidTestCompile 'com.linkedin.dexmaker:dexmaker-mockito:2.2.0'
     androidTestCompile ('com.android.support.test.espresso:espresso-core:2.2.1') {
         exclude module: 'support-annotations'
     }