Fix mention crash with overlapping ranges.

app/src/test/java/org/thoughtcrime/securesms/database/MentionUtilTest.kt

@@ -0,0 +1,49 @@
+package org.thoughtcrime.securesms.database
+
+import android.app.Application
+import org.hamcrest.MatcherAssert.assertThat
+import org.hamcrest.Matchers
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.robolectric.RobolectricTestRunner
+import org.robolectric.annotation.Config
+import org.thoughtcrime.securesms.database.model.Mention
+import org.thoughtcrime.securesms.recipients.RecipientId
+
+@RunWith(RobolectricTestRunner::class)
+@Config(manifest = Config.NONE, application = Application::class)
+class MentionUtilTest {
+
+  @Test
+  fun vanillaUpdate() {
+    val mentions = listOf(Mention(RecipientId.from(1L), 0, 1))
+
+    val update: MentionUtil.UpdatedBodyAndMentions = MentionUtil.update("T test", mentions) { it.recipientId.toString() }
+
+    assertThat(update.body, Matchers.`is`("RecipientId::1 test"))
+  }
+
+  @Test
+  fun nextToEachOtherUpdate() {
+    val mentions = listOf(
+      Mention(RecipientId.from(1L), 0, 3),
+      Mention(RecipientId.from(2L), 3, 3)
+    )
+
+    val update: MentionUtil.UpdatedBodyAndMentions = MentionUtil.update("ONETWO test", mentions) { it.recipientId.toString() }
+
+    assertThat(update.body, Matchers.`is`("RecipientId::1RecipientId::2 test"))
+  }
+
+  @Test
+  fun overlapUpdate() {
+    val mentions = listOf(
+      Mention(RecipientId.from(1L), 0, 3),
+      Mention(RecipientId.from(2L), 1, 5)
+    )
+
+    val update: MentionUtil.UpdatedBodyAndMentions = MentionUtil.update("T test", mentions) { it.recipientId.toString() }
+
+    assertThat(update.body, Matchers.`is`("RecipientId::1est"))
+  }
+}