Bug 932144 - Add option to break into debugger on test failure. r=jmaher

testing/mochitest/browser-test.js

@@ -601,6 +601,12 @@ function testResult(aCondition, aName, aDiag, aIsTodo, aStack) {
       this.result = "TEST-UNEXPECTED-PASS";
     else
       this.result = "TEST-UNEXPECTED-FAIL";
+
+    if (gConfig.debugOnFailure) {
+      // You've hit this line because you requested to break into the
+      // debugger upon a testcase failure on your test run.
+      debugger;
+    }
   }
 }
 

testing/mochitest/mach_commands.py

@@ -186,7 +186,7 @@ class MochitestRunner(MozbuildObject):
         debugger_args=None, shuffle=False, keep_open=False, rerun_failures=False,
         no_autorun=False, repeat=0, run_until_failure=False, slow=False,
         chunk_by_dir=0, total_chunks=None, this_chunk=None, jsdebugger=False,
-        start_at=None, end_at=None):
+        debug_on_failure=False, start_at=None, end_at=None):
         """Runs a mochitest.
 
         test_file is a path to a test file. It can be a relative path from the
@@ -287,6 +287,7 @@ class MochitestRunner(MozbuildObject):
         options.totalChunks = total_chunks
         options.thisChunk = this_chunk
         options.jsdebugger = jsdebugger
+        options.debugOnFailure = debug_on_failure
         options.startAt = start_at
         options.endAt = end_at
 
@@ -416,6 +417,11 @@ def MochitestCommand(func):
         help='If running tests by chunks, the number of the chunk to run.')
     func = this_chunk(func)
 
+    debug_on_failure = CommandArgument('--debug-on-failure', action='store_true',
+        help='Breaks execution and enters the JS debugger on a test failure. ' \
+             'Should be used together with --jsdebugger.')
+    func = debug_on_failure(func)
+
     jsdebugger = CommandArgument('--jsdebugger', action='store_true',
         help='Start the browser JS debugger before running the test. Implies --no-autorun.')
     func = jsdebugger(func)

testing/mochitest/mochitest_options.py

@@ -340,6 +340,12 @@ class MochitestOptions(optparse.OptionParser):
           "dest": "jsdebugger",
           "help": "open the browser debugger",
         }],
+        [["--debug-on-failure"],
+        { "action": "store_true",
+          "default": False,
+          "dest": "debugOnFailure",
+          "help": "breaks execution and enters the JS debugger on a test failure. Should be used together with --jsdebugger."
+        }],
     ]
 
     def __init__(self, **kwargs):
@@ -442,6 +448,9 @@ class MochitestOptions(optparse.OptionParser):
             ]
             options.autorun = False
 
+        if options.debugOnFailure and not options.jsdebugger:
+          self.error("--debug-on-failure should be used together with --jsdebugger.")
+
         # Try to guess the testing modules directory.
         # This somewhat grotesque hack allows the buildbot machines to find the
         # modules directory without having to configure the buildbot hosts. This

testing/mochitest/runtests.py

@@ -342,6 +342,8 @@ class MochitestUtilsMixin(object):
         self.urlOpts.append("failureFile=%s" % self.getFullPath(options.failureFile))
       if options.runSlower:
         self.urlOpts.append("runSlower=true")
+      if options.debugOnFailure:
+        self.urlOpts.append("debugOnFailure=true")
 
   def buildTestPath(self, options):
     """ Build the url path to the specific test harness and test file or directory

testing/mochitest/tests/SimpleTest/TestRunner.js

@@ -213,6 +213,12 @@ TestRunner.error = function(msg) {
     } else {
         dump(msg + "\n");
     }
+
+    if (TestRunner.debugOnFailure) {
+      // You've hit this line because you requested to break into the
+      // debugger upon a testcase failure on your test run.
+      debugger;
+    }
 };
 
 /**

testing/mochitest/tests/SimpleTest/setup.js

@@ -107,6 +107,11 @@ if (params.failureFile) {
   TestRunner.setFailureFile(params.failureFile);
 }
 
+// Breaks execution and enters the JS debugger on a test failure
+if (params.debugOnFailure) {
+  TestRunner.debugOnFailure = true;
+}
+
 // logFile to write our results
 if (params.logFile) {
   var spl = new SpecialPowersLogger(params.logFile);