refactor(workflow): contract shared core (#33)

harness/tests/test_module_boundaries.py

@@ -0,0 +1,72 @@
+"""Architecture contracts for the internal workflow modules."""
+
+from __future__ import annotations
+
+import ast
+from pathlib import Path
+
+import pytest
+
+
+THT_ROOT = Path(__file__).resolve().parents[1] / "tht"
+DOMAIN_PACKAGES = ("evidence", "memory")
+
+
+def _package(path: Path) -> tuple[str, ...]:
+    relative = path.relative_to(THT_ROOT).with_suffix("").parts
+    return ("tht", *relative[:-1])
+
+
+def _resolve_import_from(package: tuple[str, ...], node: ast.ImportFrom) -> set[str]:
+    if node.level:
+        keep = len(package) - (node.level - 1)
+        base = package[: max(keep, 0)]
+    else:
+        base = ()
+    module = (*base, *node.module.split(".")) if node.module else base
+    resolved = {".".join(module)} if module else set()
+    if not node.module or node.module == "tht":
+        resolved.update(
+            ".".join((*module, alias.name))
+            for alias in node.names
+            if alias.name != "*"
+        )
+    return resolved
+
+
+def _imports(path: Path) -> set[str]:
+    tree = ast.parse(path.read_text(), filename=str(path))
+    package = _package(path)
+    imported: set[str] = set()
+    for node in ast.walk(tree):
+        if isinstance(node, ast.Import):
+            imported.update(alias.name for alias in node.names)
+        elif isinstance(node, ast.ImportFrom):
+            imported.update(_resolve_import_from(package, node))
+    return imported
+
+
+def test_relative_import_resolution_reaches_a_sibling_domain() -> None:
+    imports = (
+        "from ..memory import core",
+        "from .. import memory",
+        "from tht import memory",
+    )
+
+    for statement in imports:
+        node = ast.parse(statement).body[0]
+        assert isinstance(node, ast.ImportFrom)
+        assert "tht.memory" in _resolve_import_from(("tht", "evidence"), node)
+
+
+@pytest.mark.parametrize("domain", DOMAIN_PACKAGES)
+def test_python_domain_does_not_import_another_domain(domain: str) -> None:
+    forbidden = {f"tht.{other}" for other in DOMAIN_PACKAGES if other != domain}
+    violations: list[str] = []
+
+    for path in sorted((THT_ROOT / domain).rglob("*.py")):
+        for imported in sorted(_imports(path)):
+            if any(imported == root or imported.startswith(f"{root}.") for root in forbidden):
+                violations.append(f"{path.relative_to(THT_ROOT)} -> {imported}")
+
+    assert violations == []