Improve user color computation and add unit tests

vector/src/main/java/im/vector/riotx/features/home/RoomColor.kt

@@ -20,7 +20,7 @@ import androidx.annotation.ColorRes
 import im.vector.riotx.R
 
 @ColorRes
-fun getColorFromRoomId(roomId: String? = null): Int {
+fun getColorFromRoomId(roomId: String?): Int {
     return when ((roomId?.toList()?.sumBy { it.toInt() } ?: 0) % 3) {
         1    -> R.color.riotx_avatar_fill_2
         2    -> R.color.riotx_avatar_fill_3

vector/src/main/java/im/vector/riotx/features/home/UserColor.kt

@@ -22,28 +22,18 @@ import kotlin.math.abs
 
 @ColorRes
 fun getColorFromUserId(userId: String?): Int {
-    if (userId.isNullOrBlank()) {
-        return R.color.riotx_username_1
-    }
-
     var hash = 0
-    var i = 0
-    var chr: Char
 
-    while (i < userId.length) {
-        chr = userId[i]
-        hash = (hash shl 5) - hash + chr.toInt()
-        i++
-    }
+    userId?.toList()?.map { chr -> hash = (hash shl 5) - hash + chr.toInt() }
 
-    return when (abs(hash) % 8 + 1) {
-        1    -> R.color.riotx_username_1
-        2    -> R.color.riotx_username_2
-        3    -> R.color.riotx_username_3
-        4    -> R.color.riotx_username_4
-        5    -> R.color.riotx_username_5
-        6    -> R.color.riotx_username_6
-        7    -> R.color.riotx_username_7
-        else -> R.color.riotx_username_8
+    return when (abs(hash) % 8) {
+        1    -> R.color.riotx_username_2
+        2    -> R.color.riotx_username_3
+        3    -> R.color.riotx_username_4
+        4    -> R.color.riotx_username_5
+        5    -> R.color.riotx_username_6
+        6    -> R.color.riotx_username_7
+        7    -> R.color.riotx_username_8
+        else -> R.color.riotx_username_1
     }
 }

vector/src/main/java/im/vector/riotx/features/home/room/detail/timeline/helper/MessageInformationDataFactory.kt

@@ -60,7 +60,7 @@ class MessageInformationDataFactory @Inject constructor(private val session: Ses
         val avatarUrl = event.senderAvatar
         val memberName = event.getDisambiguatedDisplayName()
         val formattedMemberName = span(memberName) {
-            textColor = colorProvider.getColor(getColorFromUserId(event.root.senderId ?: ""))
+            textColor = colorProvider.getColor(getColorFromUserId(event.root.senderId))
         }
 
         return MessageInformationData(

vector/src/test/java/im/vector/riotx/features/home/UserColorTest.kt

@@ -0,0 +1,42 @@
+/*
+ * Copyright 2019 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package im.vector.riotx.features.home
+
+import im.vector.riotx.R
+import org.junit.Assert.assertEquals
+import org.junit.Test
+
+class UserColorTest {
+
+    @Test
+    fun testNull() {
+        assertEquals(R.color.riotx_username_1, getColorFromUserId(null))
+    }
+
+    @Test
+    fun testEmpty() {
+        assertEquals(R.color.riotx_username_1, getColorFromUserId(""))
+    }
+
+    @Test
+    fun testName() {
+        assertEquals(R.color.riotx_username_1, getColorFromUserId("@ganfra:matrix.org"))
+        assertEquals(R.color.riotx_username_4, getColorFromUserId("@benoit0816:matrix.org"))
+        assertEquals(R.color.riotx_username_5, getColorFromUserId("@hubert:uhoreg.ca"))
+        assertEquals(R.color.riotx_username_7, getColorFromUserId("@nadonomy:matrix.org"))
+    }
+}