SERVER-8219 empty tag sets [{}] asserts with primary read preference

1 files changed, 9 insertions, 1 deletions

diff --git a/jstests/sharding/read_pref.js b/jstests/sharding/read_pref.js
index 6542a80dab1..fd69f890836 100755
--- a/jstests/sharding/read_pref.js
+++ b/jstests/sharding/read_pref.js
@@ -100,9 +100,17 @@ assert.eq( 1, explain.n );
 
 // Cannot use tags with primaryOnly
 assert.throws( function() {
-    coll.find().readPref( "primaryOnly", [] ).explain();
+    coll.find().readPref( "primary", [{ s: "2" }] ).explain();
 });
 
+
+// Ok to use empty tags on primaryOnly
+explain = coll.find().readPref("primary", [{}]).explain();
+assert.eq(primaryNode.name, explain.server);
+
+explain = coll.find().readPref("primary", []).explain();
+assert.eq(primaryNode.name, explain.server);
+
 // Check that mongos will try the next tag if nothing matches the first
 explain = coll.find().readPref( "secondary", [{ z: "3" }, { dc: "jp" }] ).explain();
 checkTag( explain.server, { dc: "jp" });