Ensures that the gold output directory exists

This will land after this CL
https://chromium-review.googlesource.com/c/424575/
as a way of making sure it works as intended.

TBR=borenet
BUG=skia:5973

Review-Url: https://codereview.chromium.org/2629943002

testing/tools/gold.py

diff --git a/testing/tools/gold.py b/testing/tools/gold.py
index fda63b6..7598caf 100644
--- a/testing/tools/gold.py
+++ b/testing/tools/gold.py
@@ -67,6 +67,10 @@
     self._results =  []
     self._outputDir = outputDir
 
+    # make sure the output directory exists.
+    if not os.path.exists(outputDir):
+      os.makedirs(outputDir)
+
   def AddTestResult(self, testName, md5Hash, outputImagePath):
     # Copy the image to <output_dir>/<md5Hash>.<image_extension>
     imgExt = os.path.splitext(outputImagePath)[1].lstrip(".")

testing/tools/test_runner.py

diff --git a/testing/tools/test_runner.py b/testing/tools/test_runner.py
index fad7a9c..92db911 100644
--- a/testing/tools/test_runner.py
+++ b/testing/tools/test_runner.py
@@ -127,10 +127,11 @@
   def HandleResult(self, input_filename, input_path, result):
     if self.gold_results:
       success, image_paths = result
-      for img_path, md5_hash in image_paths:
-        # the output filename (without extension becomes the test name)
-        test_name = os.path.splitext(os.path.split(img_path)[1])[0]
-        self.gold_results.AddTestResult(test_name, md5_hash, img_path)
+      if image_paths:
+        for img_path, md5_hash in image_paths:
+          # the output filename (without extension becomes the test name)
+          test_name = os.path.splitext(os.path.split(img_path)[1])[0]
+          self.gold_results.AddTestResult(test_name, md5_hash, img_path)
 
     if self.test_suppressor.IsResultSuppressed(input_filename):
       if result: