SERVER-47779: Clearer error message when both “atClusterTime” and “afterClusterTime” are specified

1 files changed, 16 insertions, 3 deletions

diff --git a/jstests/noPassthrough/readConcern_atClusterTime.js b/jstests/noPassthrough/readConcern_atClusterTime.js
index 9e756c488da..2a666955dc1 100644
--- a/jstests/noPassthrough/readConcern_atClusterTime.js
+++ b/jstests/noPassthrough/readConcern_atClusterTime.js
@@ -35,8 +35,8 @@ if (!testDB.serverStatus().storageEngine.supportsSnapshotReadConcern) {
     return;
 }
 
-const session = testDB.getMongo().startSession({causalConsistency: false});
-const sessionDb = session.getDatabase(dbName);
+let session = testDB.getMongo().startSession({causalConsistency: false});
+let sessionDb = session.getDatabase(dbName);
 
 const clusterTime = _getClusterTime(rst);
 
@@ -104,8 +104,21 @@ session.startTransaction(
     {readConcern: {level: "snapshot", atClusterTime: clusterTime, afterClusterTime: clusterTime}});
 assert.commandFailedWithCode(sessionDb.runCommand({find: collName}), ErrorCodes.InvalidOptions);
 assert.commandFailedWithCode(session.abortTransaction_forTesting(), ErrorCodes.NoSuchTransaction);
-
 session.endSession();
+
+// 'atClusterTime' cannot be used within causally consistent sessions.
+session = testDB.getMongo().startSession();
+sessionDb = session.getDatabase(dbName);
+// Perform a local read to establish an 'afterClusterTime' for the session.
+assert.commandWorked(sessionDb.runCommand({find: collName}));
+assert(assert
+           .commandFailedWithCode(
+               sessionDb.runCommand(
+                   {find: collName, readConcern: {level: "snapshot", atClusterTime: clusterTime}}),
+               ErrorCodes.InvalidOptions)
+           .errmsg.includes("Specifying a timestamp for readConcern snapshot in a causally " +
+                            "consistent session is not allowed"));
+
 rst.stopSet();
 
 // readConcern with 'atClusterTime' should succeed regardless of value of 'enableTestCommands'.