SERVER-21647 add missing $rename unit test

(cherry picked from commit b45dba8425b49714c5ca1394aba0bb97029c2560)

Conflicts:
	src/mongo/db/ops/modifier_rename_test.cpp

1 files changed, 7 insertions, 0 deletions

diff --git a/src/mongo/db/ops/modifier_rename_test.cpp b/src/mongo/db/ops/modifier_rename_test.cpp
index cec279f5975..6d889bb9c58 100644
--- a/src/mongo/db/ops/modifier_rename_test.cpp
+++ b/src/mongo/db/ops/modifier_rename_test.cpp
@@ -153,6 +153,13 @@ namespace {
                                ModifierInterface::Options::normal()));
     }
 
+    TEST(MoveOnSamePath, MoveToSelf) {
+        ModifierRename mod;
+        ASSERT_NOT_OK(
+            mod.init(fromjson("{'b.a':'b.a'}").firstElement(),
+                     ModifierInterface::Options::normal()));
+    }
+
     TEST(MissingTo, SimpleNumberAtRoot) {
         Document doc(fromjson("{a: 2}"));
         Mod setMod(fromjson("{$rename: {'a':'b'}}"));