Persist the Android call video bitrate range atomically

tools/chatgui-android/app/src/test/java/com/utun/chat/data/CallVideoBitrateRangeTest.kt

@@ -0,0 +1,20 @@
+package com.utun.chat.data
+
+import org.junit.Assert.*
+import org.junit.Test
+
+class CallVideoBitrateRangeTest {
+    @Test fun defaultsAndRoundTrip() {
+        assertEquals("300:4000", CallVideoBitrateRange().encode())
+        for (range in listOf(CallVideoBitrateRange(), CallVideoBitrateRange(500, 1500), CallVideoBitrateRange(300, 300))) {
+            assertEquals(range, CallVideoBitrateRange.parse(range.encode()))
+        }
+    }
+
+    @Test fun invalidPersistedRangeIsRejected() {
+        for (value in listOf("", "299:4000", "300:4001", "4000:300", "300", "300:4000x",
+            "-300:4000", "300:+4000", "300: 4000", "999999999999999999999999:4000")) {
+            assertNull(value, CallVideoBitrateRange.parse(value))
+        }
+    }
+}