Bug 1593779 - Bail out of test-verify tasks faster when there is no work to do; r=bc

This minor optimization is easily implemented: If there are no tests to verify, call fatal(0).
However, I encountered a minor obstacle: If the task exits before creating the upload directory,
the task fails, regardless of exit value; the remaining changes overcome this by creating the
upload directory earlier.

Differential Revision: https://phabricator.services.mozilla.com/D51684

--HG--
extra : moz-landing-system : lando

testing/mozharness/mozharness/mozilla/testing/per_test_base.py

@@ -269,6 +269,9 @@ class SingleTestMixin(object):
         # chunk files
         total_tests = sum([len(self.suites[x]) for x in self.suites])
 
+        if total_tests == 0:
+            self.fatal("No tests to verify: exiting.", 0)
+
         files_per_chunk = total_tests / float(self.config.get('total_chunks', 1))
         files_per_chunk = int(math.ceil(files_per_chunk))
 

testing/mozharness/scripts/desktop_unittest.py

@@ -569,6 +569,9 @@ class DesktopUnittest(TestingMixin, MercurialScript, MozbaseMixin,
     @PreScriptAction('download-and-extract')
     def _pre_download_and_extract(self, action):
         """Abort if --artifact try syntax is used with compiled-code tests"""
+        dir = self.query_abs_dirs()['abs_blob_upload_dir']
+        self.mkdir_p(dir)
+
         if not self.try_message_has_flag('artifact'):
             return
         self.info('Artifact build requested in try syntax.')
@@ -778,8 +781,6 @@ class DesktopUnittest(TestingMixin, MercurialScript, MozbaseMixin,
         """
         try:
             import psutil
-            dir = self.query_abs_dirs()['abs_blob_upload_dir']
-            self.mkdir_p(dir)
             path = os.path.join(dir, "system-info.log")
             with open(path, "w") as f:
                 f.write("System info collected at %s\n\n" % datetime.now())

testing/mozharness/scripts/web_platform_tests.py

@@ -213,11 +213,6 @@ class WebPlatformTest(TestingMixin, MercurialScript, CodeCoverageMixin, AndroidM
         cmd = [self.query_python_path('python'), '-u']
         cmd.append(os.path.join(dirs["abs_wpttest_dir"], run_file_name))
 
-        # Make sure that the logging directory exists
-        if self.mkdir_p(dirs["abs_blob_upload_dir"]) == -1:
-            self.fatal("Could not create blobber upload directory")
-            # Exit
-
         mozinfo.find_and_update_from_json(dirs['abs_test_install_dir'])
 
         cmd += ["--log-raw=-",
@@ -318,9 +313,13 @@ class WebPlatformTest(TestingMixin, MercurialScript, CodeCoverageMixin, AndroidM
                           "mozpack/*",
                           "mozbuild/*"],
             suite_categories=["web-platform"])
+        dirs = self.query_abs_dirs()
         if self.is_android:
-            dirs = self.query_abs_dirs()
             self.xre_path = self.download_hostutils(dirs['abs_xre_dir'])
+        # Make sure that the logging directory exists
+        if self.mkdir_p(dirs["abs_blob_upload_dir"]) == -1:
+            self.fatal("Could not create blobber upload directory")
+            # Exit
 
     def install(self):
         if self.is_android: