[fuzzer] create a test-suite for the fuzzer

Testrunner test-suite doesn't have automated tests for the Fuzzer. A significant
change for the testrunner may break the fuzzers. We don't have a way to catch
even the syntax errors for the fuzzer before landing CLs.

This CL creates a rudimentary test-suite that runs the fuzzer without any tests
to see if APIs still work as intended.

R=machenbach@chromium.org
CC=yangguo@chromium.org,sergiyb@chromium.org

No-Try: true
Bug: v8:8763
Change-Id: Ib4519ca093de2af5279964edd164cee04aae77a8
Reviewed-on: https://chromium-review.googlesource.com/c/1466301Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Tamer Tas <tmrts@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59535}

tools/unittests/run_tests_test.py

@@ -146,6 +146,8 @@ class SystemTest(unittest.TestCase):
     sys.path.append(TOOLS_ROOT)
     global standard_runner
     from testrunner import standard_runner
+    global num_fuzzer
+    from testrunner import num_fuzzer
     from testrunner.local import command
     from testrunner.local import pool
     command.setup_testing()
@@ -651,5 +653,16 @@ class SystemTest(unittest.TestCase):
       self.assertIn('3 tests ran', result.stdout, result)
       self.assertEqual(1, result.returncode, result)
 
+  def testNumFuzzer(self):
+    sys_args = ['--command-prefix', sys.executable, '--outdir', 'out/Release']
+
+    with temp_base() as basedir:
+      with capture() as (stdout, stderr):
+        code = num_fuzzer.NumFuzzer(basedir=basedir).execute(sys_args)
+        result = Result(stdout.getvalue(), stderr.getvalue(), code)
+
+      self.assertEqual(0, result.returncode, result)
+
+
 if __name__ == '__main__':
   unittest.main()