Added test to ensure parity between previous codes and versionchanged (…

…#869)

* Added test to ensure parity between previous codes and version
changed.

* Update test_docs.py

CHANGELOG.md

@@ -17,6 +17,8 @@ We used to have incremental versioning before `0.1.0`.
 - Forbids using nested `typing.Literal`, `typing.Union` and `typing.Annotated`
 - Forbids use of vague import names (e.g. `from json import loads`)
 - Make ``OveruseOfNoqaCommentViolation`` configurable (`--max-noqa-comments`)
+- Improves tests: we now ensure that each violation with previous codes also 
+  has corresponding versions changed in their documentation
 - Forbid incorrectly swapped variables
 - Forbids to use `+=` with list arguments
 - Forbids to use redundant subscripts (e.g., `[0:7]` or `[3:None]`)

tests/test_violations/test_docs.py

@@ -24,6 +24,16 @@ def test_violation_name(all_violations):
         assert class_name.endswith('Violation'), class_name
 
 
+def test_previous_codes_versionchanged(all_violations):
+    """Tests that we put both in case violation changes."""
+    for violation in all_violations:
+        previous_codes = getattr(violation, 'previous_codes', None)
+        if previous_codes is not None:
+            assert violation.__doc__.count(
+                '.. versionchanged::',
+            ) >= len(violation.previous_codes)
+
+
 def test_configuration(all_violations):
     """Ensures that all configuration options are listed in the docs."""
     option_listed = {