Adds layer-linter, closes #452

.travis.yml

@@ -19,6 +19,7 @@ install:
 script:
   - poetry run flake8 wemake_python_styleguide tests docs
   - poetry run mypy wemake_python_styleguide
+  - poetry run layer-lint --quiet wemake_python_styleguide
   - poetry run pytest
   - poetry run doc8 -q docs
   - poetry check

CHANGELOG.md

@@ -64,20 +64,15 @@ We used to have incremental versioning before `0.1.0`.
 - Improves docs: we have added a special graph to show our architecure
 - Improves docs: we now have a clean page for `checker` without extra junk
 - Improves docs: we now have a tutorial for creating new rules
-
-
-## Version 0.6.2
-
-### Bugfixes
-
-- Fixes a [crash](https://github.com/wemake-services/wemake-python-styleguide/issues/423) with class attributes assignment
+- Refactoring: moves `presets` package to the root
+- Improves tests: we now lint our layered architecure with `layer-lint`
 
 
 ## Version 0.6.3
 
 ### Bugfixes
 
-- Fixes a [crash](https://github.com/wemake-services/wemake-python-styleguide/issues/450) with `dict`s with just values and no keys
+- Fixes an [issue-450](https://github.com/wemake-services/wemake-python-styleguide/issues/450) with `dict`s with just values and no keys
 
 
 ## Version 0.6.2

CONTRIBUTING.md

@@ -68,6 +68,19 @@ flake8 wemake_python_styleguide tests docs
 These steps are mandatory during the CI.
 
 
+## Architecture
+
+We use [`layer-lint`](https://layer-linter.readthedocs.io/en/latest/usage.html)
+to enforce strict layered architecture.
+
+```bash
+layer-lint wemake_python_styleguide
+```
+
+All contracts must be valid for each commit.
+This step is mandatory during the CI.
+
+
 ## Type checks
 
 We use `mypy` to run type checks on our code.
@@ -122,7 +135,8 @@ Before submitting your code please do the following steps:
 7. Run `pytest` again to make sure it is still working
 8. Run `mypy` to ensure that types are correct
 9. Run `flake8` to ensure that style is correct
-10. Run `doc8` to ensure that docs are correct
+10. Run `layer-lint` to ensure that architecture contracts are correct
+11. Run `doc8` to ensure that docs are correct
 
 
 ## Other help

appveyor.yml

@@ -32,6 +32,7 @@ build: off
 test_script:
   - "poetry run flake8 wemake_python_styleguide tests docs"
   - "poetry run mypy wemake_python_styleguide"
+  - "poetry run layer-lint --quiet wemake_python_styleguide"
   - "poetry run pytest"
   - "poetry run doc8 -q docs"
   - "poetry check"

docs/pages/api.rst

@@ -50,7 +50,7 @@ our linter. This is a very simplified architecture that will help you
 to understand how all components are bound together.
 
 .. mermaid::
-   :caption: Architecture overview
+   :caption: Architecture overview.
 
    sequenceDiagram
       participant flake8
@@ -65,6 +65,11 @@ to understand how all components are bound together.
       Visitor->>Violation: Visitors raise violations when they find bad code
       Violation-->>flake8: Raised violations are shown to user by flake8
 
+We use a layered architecture that follows this contract:
+
+.. literalinclude :: ../../layers.yml
+   :language: yaml
+
 Contributing
 ------------
 

layers.yml

@@ -0,0 +1,10 @@
+Linting process:
+  containers:
+    - wemake_python_styleguide
+  layers:
+    - checker
+    - transformations
+    - presets
+    - visitors
+    - violations
+    - logics

pyproject.toml

@@ -81,3 +81,4 @@ added-value = "^0.14"
 tomlkit = "^0.5"
 safety = "^1.8"
 sphinxcontrib-mermaid = "^0.3"
+layer-linter = "^0.12.0"

tests/test_checker/test_presets.py

@@ -42,7 +42,7 @@ def _import_module_by_path(path: str):
 
 
 def _visitors_paths():
-    base_path = Path('wemake_python_styleguide', 'visitors')
+    base_path = Path('wemake_python_styleguide')
     excluded_paths = list(Path(base_path, 'presets').glob('**/*.py'))
     return [
         path for path in

wemake_python_styleguide/checker.py

@@ -49,11 +49,11 @@
 from wemake_python_styleguide.options.config import Configuration
 from wemake_python_styleguide.transformations.ast_tree import transform
 from wemake_python_styleguide.visitors import base
-from wemake_python_styleguide.visitors.presets import (
+from wemake_python_styleguide.presets import (
     complexity,
     general,
-    tokens,
 )
+from wemake_python_styleguide.presets import tokens
 
 VisitorClass = Type[base.BaseVisitor]
 

wemake_python_styleguide/presets/__init__.py

@@ -0,0 +1,3 @@
+# -*- coding: utf-8 -*-
+
+"""See :term:`preset` in the docs."""

wemake_python_styleguide/visitors/base.py

@@ -64,17 +64,13 @@
 
 import ast
 import tokenize
-from typing import TYPE_CHECKING, List, Sequence, Type
+from typing import List, Sequence, Type
 
 from wemake_python_styleguide import constants
 from wemake_python_styleguide.logics.filenames import get_stem
 from wemake_python_styleguide.types import ConfigurationOptions, final
 from wemake_python_styleguide.violations.base import BaseViolation
 
-if TYPE_CHECKING:  # pragma: no cover
-    # Hack to remove circular imports:
-    from wemake_python_styleguide.checker import Checker  # noqa: Z435
-
 
 class BaseVisitor(object):
     """
@@ -101,7 +97,7 @@ def __init__(
     @classmethod
     def from_checker(
         cls: Type['BaseVisitor'],
-        checker: 'Checker',
+        checker,
     ) -> 'BaseVisitor':
         """
         Constructs visitor instance from the checker.