Fix checking circular imports (#1668)

Author: franciszekjob

circular.py

@@ -1,7 +1,12 @@
 import importlib.util
 import os
+import shutil
 import sys
 
+import pytest
+
+PACKAGE_NAME = "starknet_py"
+
 
 def _import_from_path(module_name, file_path):
     spec = importlib.util.spec_from_file_location(module_name, file_path)
@@ -10,9 +15,81 @@ def _import_from_path(module_name, file_path):
     spec.loader.exec_module(module)
 
 
-def test_circular_imports():
-    for path, _, files in os.walk("starknet_py"):
+def assert_no_circular_imports():
+    for path, _, files in os.walk(PACKAGE_NAME):
         py_files = [f for f in files if f.endswith(".py")]
-        for file_ in py_files:
-            file_path = os.path.join(path, file_)
-            _import_from_path(file_, file_path)
+        for file in py_files:
+            file_path = os.path.join(path, file)
+            relative_path = os.path.relpath(file_path, PACKAGE_NAME)
+            module_path_no_ext = relative_path.removesuffix(".py")
+
+            # Handle __init__.py files specially
+            if module_path_no_ext.endswith("__init__"):
+                module_path_no_init = module_path_no_ext.removesuffix(
+                    "__init__"
+                ).rstrip(os.sep)
+
+                # Top-level __init__.py gives empty module path
+                if not module_path_no_init:
+                    module_name = PACKAGE_NAME
+                else:
+                    dotted_module_path = module_path_no_init.replace(os.sep, ".")
+                    module_name = f"{PACKAGE_NAME}.{dotted_module_path}"
+            else:
+                dotted_module_path = module_path_no_ext.replace(os.sep, ".")
+                module_name = f"{PACKAGE_NAME}.{dotted_module_path}"
+
+            _import_from_path(module_name, file_path)
+
+
+def test_circular_imports_absent():
+    assert_no_circular_imports()
+
+
+def _run_circular_import_test(module_name, import_a, import_b):
+    module_path = os.path.join(PACKAGE_NAME, module_name)
+    os.makedirs(module_path, exist_ok=True)
+    try:
+        with open(os.path.join(module_path, "__init__.py"), "w") as f:
+            f.write("")
+        with open(os.path.join(module_path, "file_a.py"), "w") as f:
+            f.write(f"{import_a}\nclass A:\n    pass\n")
+        with open(os.path.join(module_path, "file_b.py"), "w") as f:
+            f.write(f"{import_b}\nclass B:\n    pass\n")
+        error_regex = (
+            rf"(?:"
+            rf"cannot import name 'A' from '{PACKAGE_NAME}.{module_name}.file_a' \(.*{PACKAGE_NAME}[\\/]+{module_name}[\\/]+file_a\.py\)"
+            rf"|"
+            rf"cannot import name 'B' from '{PACKAGE_NAME}.{module_name}.file_b' \(.*{PACKAGE_NAME}[\\/]+{module_name}[\\/]+file_b\.py\)"
+            rf")"
+        )
+        with pytest.raises(ImportError, match=error_regex):
+            assert_no_circular_imports()
+    finally:
+        # Clean up temporary files
+        if os.path.exists(module_path):
+            shutil.rmtree(module_path)
+        sys.modules.pop(f"{PACKAGE_NAME}.{module_name}.file_a", None)
+        sys.modules.pop(f"{PACKAGE_NAME}.{module_name}.file_b", None)
+        sys.modules.pop(f"{PACKAGE_NAME}.{module_name}", None)
+
+
+def test_circular_imports_present():
+    _run_circular_import_test(
+        "module_x",
+        f"from {PACKAGE_NAME}.module_x.file_b import B",
+        f"from {PACKAGE_NAME}.module_x.file_a import A",
+    )
+
+
+def test_circular_imports_present_with_relative_imports():
+    # This test verifies that circular import detection works correctly when the problematic modules use
+    # relative imports (e.g., `from .file_b import B`) rather than
+    # absolute imports (e.g., `from starknet_py.module.file_b import B`),
+    # which was tested in the previous test case.
+
+    _run_circular_import_test(
+        "module_y",
+        "from .file_b import B",
+        "from .file_a import A",
+    )