SERVER-33734 Improve jsTestLog filterability

(cherry picked from commit 54dc55063a25fdcae65356c2515e55768181dc80)

3 files changed, 5 insertions, 3 deletions

diff --git a/jstests/sharding/read_pref_cmd.js b/jstests/sharding/read_pref_cmd.js
index b9f275ea962..54effe9f249 100644
--- a/jstests/sharding/read_pref_cmd.js
+++ b/jstests/sharding/read_pref_cmd.js
@@ -200,7 +200,7 @@ var testBadMode = function(conn, hostList, isMongos, mode, tagSets) {
             testDB.runReadCommand({distinct: 'user', key: 'x'});
             failureMsg = "Unexpected success running distinct!";
         } catch (e) {
-            jsTest.log(e);
+            jsTest.log(e.toString());
         }
 
         if (failureMsg)
diff --git a/jstests/sharding/zbigMapReduce.js b/jstests/sharding/zbigMapReduce.js
index 733e166745f..a1b44ab0e8a 100644
--- a/jstests/sharding/zbigMapReduce.js
+++ b/jstests/sharding/zbigMapReduce.js
@@ -135,7 +135,7 @@ function runTest(s) {
         db.foo.mapReduce(map, reduce, {out: {replace: "big_out", nonAtomic: true}});
     });
 
-    jsTest.log();
+    jsTest.log("Adding documents");
 
     // Add docs with dup "i"
     valInc = 0;
diff --git a/src/mongo/shell/utils.js b/src/mongo/shell/utils.js
index f8ed9b64ee3..a1bb04c6bfb 100644
--- a/src/mongo/shell/utils.js
+++ b/src/mongo/shell/utils.js
@@ -258,7 +258,9 @@ setJsTestOption = function(name, value) {
 };
 
 jsTestLog = function(msg) {
-    print("\n\n----\n" + msg + "\n----\n\n");
+    assert.eq(typeof(msg), "string", "Received: " + msg);
+    const msgs = ["----", ...msg.split("\n"), "----"].map(s => `[jsTest] ${s}`);
+    print(`\n\n${msgs.join("\n")}\n\n`);
 };
 
 jsTest = {};