Add first bindings unit test and enable testing.

third_party/WebKit/Tools/Scripts/run-bindings-tests

 #!/usr/bin/python
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 import sys
 
 from webkitpy.bindings.bindings_tests import run_bindings_tests
+from webkitpy.common import webkit_finder
+webkit_finder.add_typ_dir_to_sys_path()
 
+import typ
 
 def main(argv):
     """Runs Blink bindings IDL compiler on test IDL files and compares the
     results with reference files.
 
     Please execute the script whenever changes are made to the compiler
     (this is automatically done as a presubmit script),
     and submit changes to the test results in the same patch.
     This makes it easier to track and review changes in generated code.
+    """
+    argument_parser = typ.ArgumentParser()

[peria, 2016/12/12 04:43:10]

optional:
I prefer to put a routine to parse options into a separate function.

[dglazkov, 2016/12/12 05:08:22]

SG, I'll think of a way to break it up better.

+    argument_parser.add_argument('--reset-results',
+        default=False,
+        action='store_true',
+        help='Overwrites reference files with the generated results.')
+    argument_parser.add_argument('--skip-unit-tests',
+        default=False,
+        action='store_true',
+        help='Skip running unit tests (only run reference tests).')
+    argument_parser.add_argument('--skip-reference-tests',
+        default=False,
+        action='store_true',
+        help='Skip running reference tests (only run unit tests).')
 
-    Options:
-       --reset-results: Overwrites reference files with the generated results.
-       --verbose: Show output on success and logging messages (not just failure)
-    """
-    reset_results = '--reset-results' in argv
-    verbose = '--verbose' in argv
+    # First, run bindings unit tests.

[peria, 2016/12/12 04:43:10]

Why don't you use typ.main() as you did in
https://codereview.chromium.org/2554503004/?

I think it good to check if one or more tests exist,
but it is a bit too aggressive to run tests directly.

[dglazkov, 2016/12/12 05:08:22]

Ah, turns out, I can't. I need to effectively break apart typ.main, since I need
to inform typ that the embedding app has additional arguments (--reset-results),
and feed it its own argument parser. First, I had to go teach typ that this is
possible
(https://github.com/dpranke/typ/commit/c8845b2354afb6350244beb2d4430da3a2b203e3)
and Dirk graciously rolled it in to chromium over the weekend. Nesting yak
shaves! :)

I didn't realize this was necessary in
https://codereview.chromium.org/2554503004/, not until I actually tried using
--reset-results :D

Otherwise, supplying "--reset-results" as a command argument results in typ
throwing an exception, complaining of unknown argument.

+    runner = typ.Runner()
+    runner.parse_args(argument_parser, argv[1:])
+    args = runner.args
+    if argument_parser.exit_status is not None:
+        return argument_parser.exit_status
+    runner.args.top_level_dir = webkit_finder.get_bindings_scripts_dir()
+    if not args.skip_unit_tests:
+        return_code, _, _ = runner.run()
+        if return_code != 0:
+            return return_code
 
-    return run_bindings_tests(reset_results, verbose)
+    if args.skip_reference_tests:
+        return 0
+
+    # Now run the bindings end-to-end tests.
+    return run_bindings_tests(args.reset_results, args.verbose)
 
 
 if __name__ == '__main__':
     sys.exit(main(sys.argv))