Add full violations codes to docs

CHANGELOG.md

@@ -17,6 +17,11 @@ Semantic versioning in our case means:
   change the client facing API, change code conventions significantly, etc.
 
 
+## 0.16.2
+
+### Misc
+- Adds full violation codes to docs and `BaseViolation.full_code` #2409 
+
 ## 0.16.1
 
 ### Bugfixes

tests/test_violations/test_docs.py

@@ -60,3 +60,9 @@ def test_configuration(all_violations):
 
     for option_item, is_listed in option_listed.items():
         assert is_listed, option_item
+
+
+def test_all_violations_doc_start_with_full_code(all_violations):
+    """Ensures that all violations have `versionadded` tag."""
+    for violation in all_violations:
+        assert violation.__doc__.lstrip().startswith(violation.full_code)

wemake_python_styleguide/violations/base.py

@@ -67,6 +67,11 @@ class SomeViolation(ASTViolation):
 #: We use this type to define helper classes with callbacks to add violations.
 ErrorCallback = Callable[['BaseViolation'], None]
 
+def _prepend_skipping_whitespaces(prefix: str, text: str) -> str:
+    lstripped_text = text.lstrip()
+    leading_whitespaces = text[:len(text) - len(lstripped_text)]
+    return f'{leading_whitespaces}{prefix}{lstripped_text}'
+
 
 @enum.unique
 class ViolationPostfixes(enum.Enum):
@@ -98,12 +103,28 @@ class BaseViolation(object, metaclass=abc.ABCMeta):
     code: ClassVar[int]
     previous_codes: ClassVar[Set[int]]
     deprecated: ClassVar[bool] = False
+
+    # assigned in __init_subclass__
+    full_code: ClassVar[str]
+    summary: ClassVar[str]
 
     # We use this code to show base metrics and thresholds mostly:
     postfix_template: ClassVar[ViolationPostfixes] = (
         ViolationPostfixes.bigger_than
     )
 
+    def __init_subclass__(cls) -> None:
+        """
+        Derives and sets additional values for subclasses
+        """
+        if hasattr(cls, 'code'):
+            # this is mostly done for docs to display the full code,
+            # allowing its indexing in search engines and better discoverability
+            cls.full_code = cls._full_code()
+            cls.summary = cls.__doc__.lstrip().split('\n', maxsplit=1)[0]
+            # this hack adds full code to summary table in the docs
+            cls.__doc__ = _prepend_skipping_whitespaces(f'{cls.full_code} — ', cls.__doc__)
+
     def __init__(
         self,
         node: ErrorNode,
@@ -131,7 +152,7 @@ def message(self) -> str:
         Conditionally formats the ``error_template`` if it is required.
         """
         return '{0} {1}{2}'.format(
-            self._full_code(),
+            self.full_code,
             self.error_template.format(self._text),
             self._postfix_information(),
         )
@@ -142,14 +163,15 @@ def node_items(self) -> Tuple[int, int, str]:
         return (*self._location(), self.message())
 
     @final
-    def _full_code(self) -> str:
+    @classmethod
+    def _full_code(cls) -> str:
         """
         Returns fully formatted code.
 
         Adds violation letter to the numbers.
         Also ensures that codes like ``3`` will be represented as ``WPS003``.
         """
-        return 'WPS{0}'.format(str(self.code).zfill(3))
+        return 'WPS{0}'.format(str(cls.code).zfill(3))
 
     @final
     def _postfix_information(self) -> str: