SERVER-19808 Improve stack trace reports from concurrency suite

We now prepend error messages to stack traces to emulate the behavior
of v8 and to improve debuggability.

1 files changed, 6 insertions, 0 deletions

diff --git a/jstests/concurrency/fsm_libs/runner.js b/jstests/concurrency/fsm_libs/runner.js
index ffe69f6cd6b..5d6e50339c0 100644
--- a/jstests/concurrency/fsm_libs/runner.js
+++ b/jstests/concurrency/fsm_libs/runner.js
@@ -281,6 +281,12 @@ var runner = (function() {
 
         if (workerErrs.length > 0) {
             var stackTraces = workerErrs.map(function(e) {
+                if (e.err && e.stack) {
+                    // Prepend the error message to the stack trace because it
+                    // isn't automatically included in SpiderMonkey stack traces
+                    // (see: SERVER-18781).
+                    return e.err + '\n\n' + e.stack;
+                }
                 return e.stack || e.err;
             });