SQ -> Continuous Integration: Export warnings as warning annotations …

…in GitHub Actions

src/crystal/tests/index.py

@@ -245,8 +245,25 @@ def _warnings_sent_to_ci() -> Iterator[None]:
     super_showwarning = warnings.showwarning  # capture
 
     def showwarning(message, category, filename, lineno, file=None, line=None):
+        # Try to reformat `filename` to use the Linux format so that warning
+        # annotations are associated with the correct file
+        # 
+        # Depending on OS, `filename` initially looks like:
+        #     - macOS: setup/dist/Crystal Web Archiver.app/Contents/Resources/lib/python38.zip/crystal/tests/index.py
+        #     - Linux: src/crystal/tests/index.py
+        #     - Windows: crystal\tests\index.pyc
+        filename_parts = filename.split(os.path.sep)
+        if 'crystal' in filename_parts:
+            filename_parts = ['src'] + filename_parts[filename_parts.index('crystal'):]
+            if filename_parts[-1].endswith('.pyc'):
+                filename_parts[-1] = filename_parts[-1][:-1]  # convert .pyc ending to .py
+            filename = '/'.join(filename_parts)  # reinterpret
+
+        # Create warning annotation in GitHub Action's [Summary > Annotations] section
+        # 
         # Syntax: https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#example-setting-a-warning-message
         print(f'::warning file={filename},line={lineno}::{message}')
+
         return super_showwarning(message, category, filename, lineno, file, line)
 
     warnings.showwarning = showwarning