Merge pull request #392 from RocketChat/fix/crash_on_building_default_avatar

Fix crash when building default avatar 

rocket-chat-android-widgets/src/main/java/chat/rocket/android/widget/helper/UserAvatarHelper.kt

@@ -69,8 +69,11 @@ object UserAvatarHelper {
         }
 
         val splitUsername = username.split(".")
-        if (splitUsername.size > 1) {
-            return (splitUsername[0].substring(0, 1) + splitUsername[splitUsername.size - 1].substring(0, 1)).toUpperCase()
+        val splitCount = splitUsername.size
+        if (splitCount > 1 && splitUsername[0].isNotEmpty() && splitUsername[1].isNotEmpty()) {
+            val firstInitial = splitUsername[0].substring(0, 1)
+            val secondInitial = splitUsername[1].substring(0, 1)
+            return (firstInitial + secondInitial).toUpperCase()
         } else {
             if (username.length > 1) {
                 return username.substring(0, 2).toUpperCase()

rocket-chat-android-widgets/src/test/kotlin/chat/rocket/android/widget/helper/UserAvatarHelperTest.kt

@@ -18,5 +18,9 @@ class UserAvatarHelperTest {
         assert(UserAvatarHelper.getUsernameInitials("Foo.bar") == "FB")
         assert(UserAvatarHelper.getUsernameInitials("Foobar.bar") == "FB")
         assert(UserAvatarHelper.getUsernameInitials("Foobar.bar.zab") == "FZ")
+        assert(UserAvatarHelper.getUsernameInitials("..") == "..")
+        assert(UserAvatarHelper.getUsernameInitials("...") == "..")
+        assert(UserAvatarHelper.getUsernameInitials(".Foo.") == ".F")
+        assert(UserAvatarHelper.getUsernameInitials("Foo..") == "FO")
     }
 }
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