2 files changed, 114 insertions, 4 deletions
diff --git a/jstests/libs/override_methods/set_read_and_write_concerns.js b/jstests/libs/override_methods/set_read_and_write_concerns.js
index 30c853fb54b..267b5ab9bfc 100644
--- a/jstests/libs/override_methods/set_read_and_write_concerns.js
+++ b/jstests/libs/override_methods/set_read_and_write_concerns.js
@@ -57,6 +57,31 @@
         "updateUser",
     ]);
 
+    const kCommandsToEmulateWriteConcern = new Set([
+        "aggregate",
+        "appendOplogNote",
+        "captrunc",
+        "cleanupOrphaned",
+        "clone",
+        "cloneCollection",
+        "cloneCollectionAsCapped",
+        "convertToCapped",
+        "copydb",
+        "create",
+        "createIndexes",
+        "drop",
+        "dropDatabase",
+        "dropIndexes",
+        "emptycapped",
+        "godinsert",
+        "mapReduce",
+        "mapreduce",
+        "mapreduce.shardedfinish",
+        "moveChunk",
+        "renameCollection",
+        "revokePrivilegesFromRole",
+    ]);
+
     function runCommandWithReadAndWriteConcerns(
         conn, dbName, commandName, commandObj, func, makeFuncArgs) {
         if (typeof commandObj !== "object" || commandObj === null) {
@@ -79,10 +104,7 @@
 
         var shouldForceReadConcern = kCommandsSupportingReadConcern.has(commandName);
         var shouldForceWriteConcern = kCommandsSupportingWriteConcern.has(commandName);
-        var shouldEmulateWriteConcern =
-            (commandName === "aggregate" || commandName === "createIndexes" ||
-             commandName === "mapReduce" || commandName === "mapreduce" ||
-             commandName === "mapreduce.shardedfinish");
+        var shouldEmulateWriteConcern = kCommandsToEmulateWriteConcern.has(commandName);
 
         if (commandName === "aggregate") {
             if (OverrideHelpers.isAggregationWithOutStage(commandName, commandObjUnwrapped)) {
diff --git a/jstests/libs/override_methods/set_read_preference_secondary.js b/jstests/libs/override_methods/set_read_preference_secondary.js
new file mode 100644
index 00000000000..270bbf40272
--- /dev/null
+++ b/jstests/libs/override_methods/set_read_preference_secondary.js
@@ -0,0 +1,88 @@
+/**
+ * Use prototype overrides to set read preference to "secondary" when running tests.
+ */
+(function() {
+    "use strict";
+
+    load("jstests/libs/override_methods/override_helpers.js");
+
+    const kReadPreferenceSecondary = {
+        mode: "secondary"
+    };
+    const kCommandsSupportingReadPreference = new Set([
+        "aggregate",
+        "collStats",
+        "count",
+        "dbStats",
+        "distinct",
+        "find",
+        "geoNear",
+        "geoSearch",
+        "group",
+        "mapReduce",
+        "mapreduce",
+        "parallelCollectionScan",
+    ]);
+
+    function runCommandWithReadPreferenceSecondary(
+        conn, dbName, commandName, commandObj, func, makeFuncArgs) {
+        if (typeof commandObj !== "object" || commandObj === null) {
+            return func.apply(conn, makeFuncArgs(commandObj));
+        }
+
+        // If the command is in a wrapped form, then we look for the actual command object inside
+        // the query/$query object.
+        var commandObjUnwrapped = commandObj;
+        if (commandName === "query" || commandName === "$query") {
+            commandObjUnwrapped = commandObj[commandName];
+            commandName = Object.keys(commandObjUnwrapped)[0];
+        }
+
+        if (commandObj[commandName] === "system.profile") {
+            throw new Error("Cowardly refusing to run test with overridden read preference" +
+                            " when it reads from a non-replicated collection: " +
+                            tojson(commandObj));
+        }
+
+        var shouldForceReadPreference = kCommandsSupportingReadPreference.has(commandName);
+        if (OverrideHelpers.isAggregationWithOutStage(commandName, commandObjUnwrapped)) {
+            // An aggregation with a $out stage must be sent to the primary.
+            shouldForceReadPreference = false;
+        } else if ((commandName === "mapReduce" || commandName === "mapreduce") &&
+                   !OverrideHelpers.isMapReduceWithInlineOutput(commandName, commandObjUnwrapped)) {
+            // A map-reduce operation with non-inline output must be sent to the primary.
+            shouldForceReadPreference = false;
+        }
+
+        if (shouldForceReadPreference) {
+            if (commandObj === commandObjUnwrapped) {
+                // We wrap the command object using a "query" field rather than a "$query" field to
+                // match the implementation of DB.prototype._attachReadPreferenceToCommand().
+                commandObj = {
+                    query: commandObj
+                };
+            } else {
+                // We create a copy of 'commandObj' to avoid mutating the parameter the caller
+                // specified.
+                commandObj = Object.assign({}, commandObj);
+            }
+
+            if (commandObj.hasOwnProperty("$readPreference") &&
+                !bsonBinaryEqual({_: commandObj.$readPreference}, {_: kReadPreferenceSecondary})) {
+                throw new Error("Cowardly refusing to override read preference of command: " +
+                                tojson(commandObj));
+            }
+
+            commandObj.$readPreference = kReadPreferenceSecondary;
+        }
+
+        return func.apply(conn, makeFuncArgs(commandObj));
+    }
+
+    startParallelShell = () => {throw new Error(
+        "Cowardly refusing to a run a test that starts a parallel shell because prior to" +
+        " MongoDB 3.4 replica set connections couldn't be used in it.");
+    };
+
+    OverrideHelpers.overrideRunCommand(runCommandWithReadPreferenceSecondary);
+})();