Fix typo in error message.

Change-Id: I36350b0023668b47732d06b94b6fe2bddd226b05
diff --git a/src/test/java/com/android/tools/r8/maindexlist/MainDexListOutputTest.java b/src/test/java/com/android/tools/r8/maindexlist/MainDexListOutputTest.java
index 447ed7e..7565cf7 100644
--- a/src/test/java/com/android/tools/r8/maindexlist/MainDexListOutputTest.java
+++ b/src/test/java/com/android/tools/r8/maindexlist/MainDexListOutputTest.java
@@ -87,7 +87,7 @@
                     .assertErrorsMatch(
                         diagnosticMessage(
                             containsString(
-                                "--main-dex-list-output require --main-dex-rules and/or"
+                                "--main-dex-list-output requires --main-dex-rules and/or"
                                     + " --main-dex-list"))));
   }