Compress images a bit

.github/workflows/update_references.yaml

@@ -50,7 +50,7 @@ jobs:
 
           git add docrepr/tests/references
 
-          git commit -m "Update references"
+          git commit -m "Update references for ${{ matrix.os }}"
           git push
         env:
           GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

conftest.py

@@ -58,7 +58,7 @@ def _open_browser(url):
 
 @pytest.fixture
 async def compare_screenshots(request):
-    """Do visual regression tests on the output."""
+    """Run visual regression test on the output."""
     async def _compare_screenshots(test_id, url):
         if (request.config.getoption(COMPARE_SCREENSHOTS_OPTION) or
             request.config.getoption(UPDATE_REFERENCE_SCREENSHOTS_OPTION)):
@@ -89,14 +89,18 @@ async def _compare_screenshots(test_id, url):
                 await page.screenshot(path=screenshot)
                 await browser.close()
 
+            # Compress the screenshot
+            screenshot_im = Image.open(screenshot).convert('RGB')
+            screenshot_im.save(screenshot, quality=80, optimize=True)
+
+            # If a reference update has been requested, we copy the screenshot
+            # and consider the test as "passing"
             if request.config.getoption(UPDATE_REFERENCE_SCREENSHOTS_OPTION):
                 shutil.copyfile(screenshot, reference)
-                # Do not run the visual regression test
                 return
 
             # Compare the screenshot with the reference
             reference_im = Image.open(reference).convert('RGB')
-            screenshot_im = Image.open(screenshot).convert('RGB')
             diff_im = ImageChops.difference(screenshot_im, reference_im)
 
             bbox = diff_im.getbbox()