Fix compare-changes wildcard matching and add automated testing

.github/workflows/compare-changes.yml

@@ -0,0 +1,20 @@
+name: compare-changes
+on:
+  pull_request:
+    paths:
+      - ".github/workflows/compare-changes.yml"
+      - "compare-changes/**/*"
+      - "!compare-changes/README.md"
+
+jobs:
+  test:
+    name: Test
+    runs-on: [ubuntu-24.04]
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Run tests
+        shell: sh
+        run: |
+          python3 ./compare-changes/test.py

compare-changes/.gitignore

@@ -0,0 +1 @@
+__pycache__

compare-changes/action.py

@@ -1,7 +1,6 @@
 #!/usr/bin/env python3
 import os
 import json
-import yaml
 import fnmatch
 
 
@@ -12,6 +11,7 @@ def convert_github_patterns_to_fnmatch(github_patterns):
     Handles common GitHub Actions path wildcard patterns:
     - dir/** -> dir/*
     - dir/**/* -> dir/*
+    - **/*.file -> *.file
 
     Returns a list of converted patterns.
     """
@@ -26,6 +26,10 @@ def convert_github_patterns_to_fnmatch(github_patterns):
         elif pattern.endswith("**/*"):
             converted = pattern[:-4] + "*"
             fnmatch_patterns.append(converted)
+        # Handle **/*.file pattern (matches any .file at any depth)
+        elif pattern.startswith("**/*."):
+            converted = pattern[3:]
+            fnmatch_patterns.append(converted)
         # Keep other patterns as is
         else:
             fnmatch_patterns.append(pattern)
@@ -64,18 +68,21 @@ def extract_path_patterns(config):
     )
 
 
-def check_for_matches(path_patterns, changed_files):
-    """Check if any changed file matches any path pattern."""
+def check_for_matches(original_patterns, fnmatch_patterns, changed_files):
+    """Check if any changed file matches any path pattern, using original pattern intent."""
     for changed_file in changed_files:
-        for pattern in path_patterns:
-            # For patterns without slashes that aren't directory patterns,
-            # ensure they only match at the root level
-            if "/" not in pattern and "*" in pattern and "/" in changed_file:
+        for orig_pattern, fn_pattern in zip(original_patterns, fnmatch_patterns):
+            # Only restrict to root-level if the original pattern does NOT contain a slash or '**/'
+            is_root_only = "/" not in orig_pattern and not orig_pattern.startswith(
+                "**/"
+            )
+            if is_root_only and "*" in fn_pattern and "/" in changed_file:
                 # Skip files in subdirectories for root-level patterns
                 continue
-
-            if fnmatch.fnmatch(changed_file, pattern):
-                print(f"File '{changed_file}' matches pattern '{pattern}'")
+            if fnmatch.fnmatch(changed_file, fn_pattern):
+                print(
+                    f"File '{changed_file}' matches pattern '{fn_pattern}' (original: '{orig_pattern}')"
+                )
                 print(
                     "Returning early as an optimisation, there may be more matches not listed here."
                 )
@@ -84,6 +91,8 @@ def check_for_matches(path_patterns, changed_files):
 
 
 def main():
+    import yaml  # Only import yaml when main() is run
+
     # Get inputs from environment variables
     changes_json = os.environ.get("INPUT_CHANGES", "[]")
     wildcard_name = os.environ.get("INPUT_WILDCARD")
@@ -125,7 +134,7 @@ def main():
                 print(f"- '{before}' -> '{after}'")
 
         # Check for matches (using converted patterns)
-        matched = check_for_matches(fnmatch_patterns, changed_files)
+        matched = check_for_matches(path_patterns, fnmatch_patterns, changed_files)
 
         # Output the result to GitHub Actions
         appending_mode = "a"

compare-changes/test.py

@@ -0,0 +1,102 @@
+import sys
+import os
+import importlib.util
+
+# Dynamically import action.py as a module
+script_dir = os.path.dirname(os.path.abspath(__file__))
+action_path = os.path.join(script_dir, "action.py")
+spec = importlib.util.spec_from_file_location("action", action_path)
+action = importlib.util.module_from_spec(spec)
+sys.modules["action"] = action
+spec.loader.exec_module(action)
+
+
+def test_check_for_matches():
+    """Table-driven tests for pattern matching logic."""
+    test_cases = [
+        # pattern, changeset, expected_result
+        {
+            "patterns": ["*.yml"],
+            "changes": ["foo.yml", "bar/test.yml"],
+            "expected": True,
+        },
+        {
+            "patterns": ["*.yml"],
+            "changes": ["bar/test.yml"],
+            "expected": False
+        },
+        {
+            "patterns": ["**/*.yml"],
+            "changes": ["foo.yml", "bar/test.yml"],
+            "expected": True,
+        },
+        {
+            "patterns": ["dir/**"],
+            "changes": ["dir/file.txt", "dir/sub/file.txt"],
+            "expected": True,
+        },
+        {
+            "patterns": ["dir/**"],
+            "changes": ["dir/sub/file.txt"],
+            "expected": True,
+        },
+        {
+            "patterns": ["dir/**/*"],
+            "changes": ["dir/file.txt", "dir/sub/file.txt"],
+            "expected": True,
+        },
+        {
+            "patterns": ["dir/**/*"],
+            "changes": ["dir/sub/file.txt"],
+            "expected": True,
+        },
+        {
+            "patterns": ["**/*.py"],
+            "changes": ["main.py", "src/app.py", "docs/readme.md"],
+            "expected": True,
+        },
+        {
+            "patterns": ["**/*.py"],
+            "changes": ["src/foo/app.py"],
+            "expected": True,
+        },
+        {
+            "patterns": ["*.md"],
+            "changes": ["docs/readme.md"],
+            "expected": False
+        },
+        {
+            "patterns": ["*.md"],
+            "changes": ["readme.md"],
+            "expected": True
+        },
+        {
+            "patterns": ["**/*.md"],
+            "changes": ["docs/readme.md"],
+            "expected": True
+        },
+        {
+            "patterns": ["foo/bar.txt"],
+            "changes": ["foo/bar.txt", "bar/foo.txt"],
+            "expected": True,
+        },
+        {
+            "patterns": ["foo/bar.txt"],
+            "changes": ["bar/foo.txt"],
+            "expected": False
+        },
+    ]
+    for i, case in enumerate(test_cases):
+        fnmatch_patterns = action.convert_github_patterns_to_fnmatch(case["patterns"])
+        result = action.check_for_matches(
+            case["patterns"], fnmatch_patterns, case["changes"]
+        )
+        print(
+            f"Test case {i + 1}: patterns={case['patterns']} changes={case['changes']}\nExpected: {case['expected']} Got: {result}"
+        )
+        assert result == case["expected"], f"Failed test case {i + 1}"
+    print("All tests passed.")
+
+
+if __name__ == "__main__":
+    test_check_for_matches()