Fix mention crash with overlapping ranges.

app/src/main/java/org/thoughtcrime/securesms/database/MentionUtil.java

@@ -5,6 +5,7 @@ import android.text.SpannableStringBuilder;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
+import androidx.annotation.VisibleForTesting;
 import androidx.annotation.WorkerThread;
 
 import com.annimon.stream.Stream;
@@ -64,7 +65,8 @@ public final class MentionUtil {
     return update(body, mentions, m -> MENTION_PLACEHOLDER);
   }
 
-  private static @NonNull UpdatedBodyAndMentions update(@Nullable CharSequence body, @NonNull List<Mention> mentions, @NonNull Function<Mention, CharSequence> replacementTextGenerator) {
+  @VisibleForTesting
+  static @NonNull UpdatedBodyAndMentions update(@Nullable CharSequence body, @NonNull List<Mention> mentions, @NonNull Function<Mention, CharSequence> replacementTextGenerator) {
     if (body == null || mentions.isEmpty()) {
       return new UpdatedBodyAndMentions(body, mentions);
     }
@@ -76,7 +78,7 @@ public final class MentionUtil {
     int bodyIndex = 0;
 
     for (Mention mention : sortedMentions) {
-      if (invalidMention(body, mention)) {
+      if (invalidMention(body, mention) || bodyIndex > mention.getStart()) {
         continue;
       }
 

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"))
+  }
+}