Fix some small bugs in error handlers for image capture

lib/wraith/save_images.rb

@@ -76,7 +76,7 @@ def run_command(command)
   end
 
   def parallel_task(jobs)
-    Parallel.each(jobs, :in_threads => wraith.threads) do |_label, _path, width, url, filename, selector, global_before_capture, path_before_capture|
+    Parallel.each(jobs, :in_threads => wraith.threads) do |_label, _path, width, url, filename, selector, global_before_capture, path_before_capture, invalid_image_name|
       begin
         if meta.engine == "chrome"
           capture_image_selenium(width, url, filename, selector, global_before_capture, path_before_capture)
@@ -143,7 +143,7 @@ def capture_image_selenium(screen_sizes, url, file_name, selector, global_before
           crop_selector(driver, selector, new_file_name) if selector && selector.length > 0
           break
         rescue Net::ReadTimeout => e
-          logger.error "Got #{e} on attempt #{attempt} at screen size #{screensize}. URL = #{url}"
+          logger.error "Got #{e} on attempt #{attempt} at screen size #{screen_size}. URL = #{url}"
         end
       end
     end

spec/save_images_spec.rb

@@ -70,4 +70,31 @@
       expect(File).to exist("shots/thumbnails/test/test_diff.png")
     end
   end
+
+  describe "when parallelising jobs" do
+    context "when something goes wrong" do
+      it "creates a dummy invalid image" do
+        allow(saving).to receive(:attempt_image_capture).and_raise("boom")
+        # Create the image at the original res of the invalid image, so that we
+        # can compare its md5 easily
+        jobs = [
+          ['test', '/test/path', '1500x1500', test_url1, test_image1, nil, nil, nil,
+           'invalid1.jpg']
+        ]
+        saving.parallel_task(jobs)
+        # Create the expected image so we can compare them, because they'll
+        # differ between imagemagick versions and platforms and so we can't just
+        # use a fixture.
+        saving.create_invalid_image("shots/test/invalid1.png", 1500, "invalid1.jpg")
+        Wraith::CompareImages.new(config_name).compare_task(
+          test_image1,
+          "shots/test/invalid1.png",
+          "shots/test/test_diff.png",
+          "shots/test/test.txt"
+        )
+        diff = File.open("shots/test/test.txt", "rb").read
+        expect(diff).to eq "0.0"
+      end
+    end
+  end
 end