Replace recipes_test.py with a new parallel expectation-based test runner.

scripts/slave/unittests/expect_tests/handle_debug.py

+# Copyright 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import sys
+import pdb
+
+from .types import Handler
+
+class DebugHandler(Handler):
+  """Execute each test under the pdb debugger."""
+  SKIP_RUNLOOP = True
+
+  class ResultStageHandler(Handler.ResultStageHandler):
+    @staticmethod
+    def Test(test):
+      dbg = pdb.Pdb()
+      for path, line, funcname in test.breakpoints:
+        dbg.set_break(path, line, funcname=funcname)
+
+      dbg.reset()
+
+      def dispatch_thunk(*args):
+        """Allows us to continue until the actual breakpoint."""
+        val = dbg.trace_dispatch(*args)
+        dbg.set_continue()
+        sys.settrace(dbg.trace_dispatch)
+        return val
+      sys.settrace(dispatch_thunk)
+      try:
+        test.run()
+      except pdb.bdb.BdbQuit:
+        pass
+      finally:
+        dbg.quitting = 1
+        sys.settrace(None)