Improve requirements.yml detection (#275)

Gives explicit error message about invalid requirements.yml files,
especially as an unsupported format was used during the 2020 split.

Closes: #274
Related: ansible-community/community-topics#230

Author: ssbarnea

examples/reqs_broken/requirements.yml

@@ -0,0 +1,4 @@
+roles: []
+collections: []
+integration_tests_dependencies: [] # <-- invalid key
+unit_tests_dependencies: [] # <-- invalid key

src/ansible_compat/constants.py

@@ -1,6 +1,16 @@
 """Constants used by ansible_compat."""
 
 
+REQUIREMENT_LOCATIONS = [
+    "requirements.yml",
+    "roles/requirements.yml",
+    "collections/requirements.yml",
+    # These is more of less the official way to store test requirements in collections so far, comments shows number of repos using this reported by https://sourcegraph.com/ at the time of writing
+    "tests/requirements.yml",  # 170
+    "tests/integration/requirements.yml",  # 3
+    "tests/unit/requirements.yml",  # 1
+]
+
 # Minimal version of Ansible we support for runtime
 ANSIBLE_MIN_VERSION = "2.12"
 

src/ansible_compat/runtime.py

@@ -22,7 +22,11 @@
     ansible_collections_path,
     parse_ansible_version,
 )
-from ansible_compat.constants import MSG_INVALID_FQRL, RC_ANSIBLE_OPTIONS_ERROR
+from ansible_compat.constants import (
+    MSG_INVALID_FQRL,
+    RC_ANSIBLE_OPTIONS_ERROR,
+    REQUIREMENT_LOCATIONS,
+)
 from ansible_compat.errors import (
     AnsibleCommandError,
     AnsibleCompatError,
@@ -411,6 +415,12 @@ def install_requirements(  # noqa: C901
             msg = f"{requirement} file is not a valid Ansible requirements file."
             raise InvalidPrerequisiteError(msg)
 
+        if isinstance(reqs_yaml, dict):
+            for key in reqs_yaml:
+                if key not in ("roles", "collections"):
+                    msg = f"{requirement} file is not a valid Ansible requirements file. Only 'roles' and 'collections' keys are allowed at root level. Recognized valid locations are: {', '.join(REQUIREMENT_LOCATIONS)}"
+                    raise InvalidPrerequisiteError(msg)
+
         if isinstance(reqs_yaml, list) or "roles" in reqs_yaml:
             cmd = [
                 "ansible-galaxy",
@@ -485,13 +495,7 @@ def prepare_environment(  # noqa: C901
         # are part of Tower specification
         # https://docs.ansible.com/ansible-tower/latest/html/userguide/projects.html#ansible-galaxy-support
         # https://docs.ansible.com/ansible-tower/latest/html/userguide/projects.html#collections-support
-        for req_file in [
-            "requirements.yml",
-            "roles/requirements.yml",
-            "collections/requirements.yml",
-            # These is more of less the official way to store test requirements in collections so far:
-            "tests/requirements.yml",
-        ]:
+        for req_file in REQUIREMENT_LOCATIONS:
             self.install_requirements(Path(req_file), retry=retry, offline=offline)
 
         galaxy_path = Path("galaxy.yml")

test/test_runtime.py

@@ -258,6 +258,13 @@ def test_prerun_reqs_v2(caplog: pytest.LogCaptureFixture, runtime: Runtime) -> N
         )
 
 
+def test_prerun_reqs_broken(runtime: Runtime) -> None:
+    """Checks that the we report invalid requirements.yml file."""
+    path = (Path(__file__).parent.parent / "examples" / "reqs_broken").resolve()
+    with cwd(path), pytest.raises(InvalidPrerequisiteError):
+        runtime.prepare_environment()
+
+
 def test__update_env_no_old_value_no_default_no_value(monkeypatch: MonkeyPatch) -> None:
     """Make sure empty value does not touch environment."""
     monkeypatch.delenv("DUMMY_VAR", raising=False)

tox.ini

@@ -68,7 +68,7 @@ setenv =
   PIP_DISABLE_PIP_VERSION_CHECK = 1
   PIP_CONSTRAINT = {toxinidir}/requirements.txt
   PRE_COMMIT_COLOR = always
-  PYTEST_REQPASS = 80
+  PYTEST_REQPASS = 81
   FORCE_COLOR = 1
 allowlist_externals =
   ansible