Merge pull request #156 from jamescooke/assignment-expression

Assert compatibility with Python 3.8's assignment expression

CHANGELOG.rst

@@ -14,6 +14,13 @@ Unreleased_
 See also `latest documentation
 <https://flake8-aaa.readthedocs.io/en/latest/#__unreleased_marker__>`_.
 
+Added
+.....
+
+* Add good example usage of the assignment expression in Python 3.8 to
+  guarantee compatibility. `#120
+  <https://github.com/jamescooke/flake8-aaa/issues/120>`_.
+
 Changed
 .......
 
@@ -28,7 +35,11 @@ Added
 .....
 
 * Test examples are intended to be real but simple examples. All examples added
-  or updated are now executed with pytest and no imports and must be green.
+  or updated from now on must:
+
+  - Go green when run with Pytest.
+
+  - Use only standard library imports.
 
 Changed
 .......

Makefile

@@ -23,7 +23,6 @@ tox:
 
 # --- Tox recipes ---
 
-# Tox: -e "py3{6,7,8}-lint"
 .PHONY: lint
 lint:
 	@echo "=== flake8 ==="
@@ -48,37 +47,40 @@ fixlint:
 	@echo "=== fixing yapf ==="
 	yapf --recursive --in-place $(lint_files)
 
-# Tox: -e "py3{6,7,8}-lintexamples"
 .PHONY: lintexamples
 lintexamples:
 	@echo "=== flake8 ==="
-	flake8 examples | sort > flake8.out
+	flake8 examples/good examples/bad | sort > flake8.out
 	diff examples/bad/flake8_expected.out flake8.out
 	@echo "=== mypy ==="
 	mypy examples examples/good --ignore-missing-imports
 	mypy examples/bad --ignore-missing-imports
 	@echo "=== black ==="
 	black --check --diff --verbose examples/good/black
 
+.PHONY: lintexamplespy38
+lintexamplespy38:
+	@echo "=== flake8 ==="
+	flake8 examples/good_py38
+	@echo "=== mypy ==="
+	mypy examples/good_py38
+
 .PHONY: fixlintexamples
 fixlintexamples:
 	@echo "=== black ==="
 	black examples/good/black
 
-# Tox: -e "py36-doc"
 .PHONY: doc
 doc:
 	$(MAKE) -C docs html
 
-# Tox: -e "py3{6,7,8}-cmd"
 .PHONY: cmd
 cmd:
 	for i in $(good_examples); do \
 		echo "\n=== $$i ==="; \
 		python -m flake8_aaa "$$i" || break -1; \
 	done
 
-# Tox: -e "py3{6,7,8}-cmdbad"
 # NOTE: Checks that all bad example files give at least 1 error and all return
 # an error code greater than 0. The `echo;` is used to wipe the error code from
 # the last test, or the for loop fails.

examples/good_py38/test_assignment_operator.py

@@ -0,0 +1,10 @@
+def test():
+    """
+    clear() removes all items from a list
+    """
+    shopping = ["apples", "bananas", "cabbages"]
+
+    result = shopping.clear()
+
+    assert result is None
+    assert (n := len(shopping)) == 0, f"Expected 0 items of shopping, got {n}"

requirements/base.txt

@@ -5,8 +5,8 @@
 #    pip-compile --output-file=base.txt base.in
 #
 asttokens==2.0.4          # via -r base.in
-flake8==3.8.2             # via -r base.in
-importlib-metadata==1.6.0  # via flake8
+flake8==3.8.3             # via -r base.in
+importlib-metadata==1.6.1  # via flake8
 mccabe==0.6.1             # via flake8
 pycodestyle==2.6.0        # via flake8
 pyflakes==2.2.0           # via flake8

requirements/dev.txt

@@ -5,18 +5,18 @@
 #    pip-compile --output-file=dev.txt dev.in
 #
 bleach==3.1.5             # via readme-renderer
-certifi==2020.4.5.1       # via -c test.txt, requests
+certifi==2020.4.5.2       # via -c test.txt, requests
 cffi==1.14.0              # via cryptography
 chardet==3.0.4            # via -c test.txt, requests
 click==7.1.2              # via pip-tools
 cryptography==2.9.2       # via secretstorage
 docutils==0.16            # via -c test.txt, readme-renderer
 idna==2.9                 # via -c test.txt, requests
-importlib-metadata==1.6.0  # via -c base.txt, -c test.txt, keyring, twine
+importlib-metadata==1.6.1  # via -c base.txt, -c test.txt, keyring, twine
 jeepney==0.4.3            # via keyring, secretstorage
 keyring==21.2.1           # via twine
 packaging==20.4           # via -c test.txt, bleach
-pip-tools==5.1.2          # via -r dev.in
+pip-tools==5.2.1          # via -r dev.in
 pkginfo==1.5.0.1          # via twine
 pycparser==2.20           # via cffi
 pygments==2.6.1           # via -c test.txt, readme-renderer
@@ -26,7 +26,7 @@ requests-toolbelt==0.9.1  # via twine
 requests==2.23.0          # via -c test.txt, requests-toolbelt, twine
 secretstorage==3.1.2      # via keyring
 six==1.15.0               # via -c base.txt, -c test.txt, bleach, cryptography, packaging, pip-tools, readme-renderer
-tqdm==4.46.0              # via twine
+tqdm==4.46.1              # via twine
 twine==3.1.1              # via -r dev.in
 urllib3==1.25.9           # via -c test.txt, requests
 webencodings==0.5.1       # via bleach

requirements/examples.txt

@@ -8,24 +8,24 @@ appdirs==1.4.4            # via black
 attrs==19.3.0             # via black, pytest
 black==19.10b0            # via -r examples.in
 click==7.1.2              # via black
-flake8==3.8.2             # via -r examples.in
-importlib-metadata==1.6.0  # via flake8, pluggy, pytest
+flake8==3.8.3             # via -r examples.in
+importlib-metadata==1.6.1  # via flake8, pluggy, pytest
 mccabe==0.6.1             # via flake8
 more-itertools==8.3.0     # via pytest
 mypy-extensions==0.4.3    # via mypy
-mypy==0.770               # via -r examples.in
+mypy==0.780               # via -r examples.in
 packaging==20.4           # via pytest
 pathspec==0.8.0           # via black
 pluggy==0.13.1            # via pytest
 py==1.8.1                 # via pytest
 pycodestyle==2.6.0        # via flake8
 pyflakes==2.2.0           # via flake8
 pyparsing==2.4.7          # via packaging
-pytest==5.4.2             # via -r examples.in
-regex==2020.5.14          # via black
+pytest==5.4.3             # via -r examples.in
+regex==2020.6.8           # via black
 six==1.15.0               # via packaging
 toml==0.10.1              # via black
 typed-ast==1.4.1          # via black, mypy
 typing-extensions==3.7.4.2  # via mypy
-wcwidth==0.1.9            # via pytest
+wcwidth==0.2.4            # via pytest
 zipp==3.1.0               # via importlib-metadata

requirements/test.txt

@@ -8,51 +8,51 @@ alabaster==0.7.12         # via sphinx
 appdirs==1.4.4            # via virtualenv
 attrs==19.3.0             # via pytest
 babel==2.8.0              # via sphinx
-certifi==2020.4.5.1       # via requests
+certifi==2020.4.5.2       # via requests
 chardet==3.0.4            # via requests
 distlib==0.3.0            # via virtualenv
 docutils==0.16            # via restructuredtext-lint, sphinx
 filelock==3.0.12          # via tox, virtualenv
-flake8==3.8.2             # via -c base.txt, -r test.in
+flake8==3.8.3             # via -c base.txt, -r test.in
 idna==2.9                 # via requests
 imagesize==1.2.0          # via sphinx
-importlib-metadata==1.6.0  # via -c base.txt, flake8, importlib-resources, pluggy, pytest, tox, virtualenv
+importlib-metadata==1.6.1  # via -c base.txt, flake8, importlib-resources, pluggy, pytest, tox, virtualenv
 importlib-resources==1.5.0  # via virtualenv
 isort==4.3.21             # via -r test.in
 jinja2==2.11.2            # via sphinx
 markupsafe==1.1.1         # via jinja2
 mccabe==0.6.1             # via -c base.txt, flake8
 more-itertools==8.3.0     # via pytest
 mypy-extensions==0.4.3    # via mypy
-mypy==0.770               # via -r test.in
+mypy==0.780               # via -r test.in
 packaging==20.4           # via pytest, sphinx, tox
 pluggy==0.13.1            # via pytest, tox
 py==1.8.1                 # via pytest, tox
 pycodestyle==2.6.0        # via -c base.txt, flake8
 pyflakes==2.2.0           # via -c base.txt, flake8
 pygments==2.6.1           # via -r test.in, sphinx
 pyparsing==2.4.7          # via packaging
-pytest==5.4.2             # via -r test.in
+pytest==5.4.3             # via -r test.in
 pytz==2020.1              # via babel
 requests==2.23.0          # via sphinx
-restructuredtext-lint==1.3.0  # via -r test.in
+restructuredtext-lint==1.3.1  # via -r test.in
 six==1.15.0               # via -c base.txt, -r test.in, packaging, tox, virtualenv
 snowballstemmer==2.0.0    # via sphinx
 sphinx-rtd-theme==0.4.3   # via -r test.in
-sphinx==3.0.3             # via -r test.in, sphinx-rtd-theme
+sphinx==3.1.0             # via -r test.in, sphinx-rtd-theme
 sphinxcontrib-applehelp==1.0.2  # via sphinx
 sphinxcontrib-devhelp==1.0.2  # via sphinx
 sphinxcontrib-htmlhelp==1.0.3  # via sphinx
 sphinxcontrib-jsmath==1.0.1  # via sphinx
 sphinxcontrib-qthelp==1.0.3  # via sphinx
 sphinxcontrib-serializinghtml==1.1.4  # via sphinx
 toml==0.10.1              # via tox
-tox==3.15.1               # via -r test.in
+tox==3.15.2               # via -r test.in
 typed-ast==1.4.1          # via mypy
 typing-extensions==3.7.4.2  # via mypy
 urllib3==1.25.9           # via requests
 virtualenv==20.0.21       # via tox
-wcwidth==0.1.9            # via pytest
+wcwidth==0.2.4            # via pytest
 yapf==0.30.0              # via -r test.in
 zipp==3.1.0               # via -c base.txt, importlib-metadata, importlib-resources
 

tox.ini

@@ -44,6 +44,7 @@ commands =
     cmdbad: make cmdbad
     doc: make doc
     examples: {[examples]commands}
+    py38-examples: {[py38-examples]commands}
     examples_aaa: {[examples_aaa]commands}
     install: {[install]commands}
     lint: make lint
@@ -69,13 +70,19 @@ commands =
 commands =
     make lintexamples
     pytest \
+        examples/good/black/test_context_block_act.py \
         examples/good/test_with_statement.py \
         examples/good/test_with_statement_unittest.py \
-        examples/good/black/test_context_block_act.py \
         examples/bad/test_aaa03.py \
         examples/bad/test_aaa03_04.py \
         examples/bad/test_aaa04.py
 
+[py38-examples]
+# Add extra checks on Python 3.8 files
+commands =
+    make lintexamplespy38
+    pytest examples/good_py38/test_assignment_operator.py
+
 [examples_aaa]
 commands =
     flake8 --version