chore: add pre-commit hook to check for absolute imports in routingpy package (#151)

* disallow absolute imports, check it in pre-commit hook
* cancel running ci workflows

Author: nilsnolde

.github/workflows/ci-tests.yml

@@ -15,6 +15,12 @@ on:
       - '.gitignore'
       - '**.md'
       - '**.rst'
+        
+# Cancel CI runs on a branch when new commits were pushed
+# See https://stackoverflow.com/a/72408109/2582935
+concurrency:
+  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
 
 jobs:
   build:

.pre-commit-config.yaml

@@ -14,3 +14,10 @@ repos:
     - id: isort
       name: isort (python)
       args: [--filter-files]
+- repo: local
+  hooks:
+    - id: no-absolute-imports
+      name: Disallow absolute self-imports
+      entry: python tests/scripts/check_imports.py routingpy routingpy
+      language: system
+      pass_filenames: false

tests/scripts/check_imports.py

@@ -0,0 +1,43 @@
+#!/usr/bin/env python3
+
+# Errors on absolute imports in any .py files found in the input paths
+
+import re
+import sys
+from pathlib import Path
+
+
+def check_for_absolute_imports(library_name: str, *dirs):
+    """
+    Ensures no absolute imports of the library (e.g. 'import mylib' or 'from mylib import ...')
+    appear outside test files.
+    """
+    # only matches "from/import <library_name>", while "from/import <library-name>-other" is allowed
+    abs_import_pattern = re.compile(rf"^\s*(?:from|import)\s+{re.escape(library_name)}(?=\.|\s|$)")
+
+    errors = []
+    for dir in dirs:
+        dir_path = Path(dir)
+        for py_file in dir_path.rglob("*.py"):
+            with py_file.open() as f:
+                dir_rel_path = py_file.absolute().relative_to(Path.cwd())
+                for lineno, line in enumerate(f, 1):
+                    if not abs_import_pattern.search(line):
+                        continue
+                    errors.append(f"{dir_rel_path}:{lineno}: {line.strip()}")
+
+    if errors:
+        print(f"❌ Absolute imports of {library_name} found outside tests:")
+        print("\n".join(errors))
+        sys.exit(1)
+    else:
+        print("✅ No forbidden absolute imports found.")
+        sys.exit(0)
+
+
+if __name__ == "__main__":
+    if len(sys.argv) < 3:
+        print("Usage: python check_imports.py <library_name> <dirpath1> [<dirpath2>] ...")
+        sys.exit(1)
+
+    check_for_absolute_imports(sys.argv[1], *sys.argv[2:])