Manage black version using requirement file

.appveyor.yml

@@ -103,11 +103,6 @@ for:
       - sh: "sudo unzip -d /opt/gradle /tmp/gradle-*.zip"
       - sh: "PATH=/opt/gradle/gradle-5.5/bin:$PATH"
 
-      # Install black
-      - sh: "wget -O /tmp/black https://github.com/python/black/releases/download/19.10b0/black"
-      - sh: "chmod +x /tmp/black"
-      - sh: "/tmp/black --version"
-
     build_script:
       - "python -c \"import sys; print(sys.executable)\""
       - "LAMBDA_BUILDERS_DEV=1 pip install -e \".[dev]\""
@@ -119,5 +114,5 @@ for:
       # Runs only in Linux
       - "LAMBDA_BUILDERS_DEV=1 pytest -vv tests/integration"
 
-      # Validate Code was formatted with Black
-      - "/tmp/black --check setup.py tests aws_lambda_builders"
+      # Validate Code was formatted with Black, black is only supported in Python 3
+      - if [[ $PYTHON_VERSION = "3"* ]]; then black --check setup.py tests aws_lambda_builders; fi

.pre-commit-config.yaml

@@ -0,0 +1,9 @@
+# black is in dev.txt, so local repo is used here.
+repos:
+- repo: local
+  hooks:
+    - id: black
+      name: black
+      entry: black
+      language: system
+      types: [python]

Makefile

@@ -28,3 +28,6 @@ black-check:
 
 # Verifications to run before sending a pull request
 pr: init dev black-check
+
+# Verifications to run before sending a pull request, skipping black check because black requires Python 3.6+
+pr2.7: init dev

requirements/dev.txt

@@ -20,3 +20,7 @@ futures==3.2.0; python_version<"3.2.3"
 
 # tempfile backport for < 3.6
 backports.tempfile==1.0; python_version<"3.7"
+
+
+# formatter
+black==20.8b1; python_version >= '3.6'

tests/functional/workflows/provided_make/test_utils.py

@@ -30,7 +30,11 @@ def test_popen_can_accept_cwd_and_env(self):
         env.update({"SOME_ENV": "SOME_VALUE"})
 
         p = self.osutils.popen(
-            [sys.executable, "cwd.py"], stdout=self.osutils.pipe, stderr=self.osutils.pipe, env=env, cwd=testdata_dir,
+            [sys.executable, "cwd.py"],
+            stdout=self.osutils.pipe,
+            stderr=self.osutils.pipe,
+            env=env,
+            cwd=testdata_dir,
         )
 
         out, err = p.communicate()

tests/unit/test_builder.py

@@ -62,8 +62,7 @@ def test_must_not_load_any_workflows(self, get_workflow_mock, importlib_mock):
         importlib_mock.import_module.assert_not_called()
 
     def test_with_real_workflow_class(self):
-        """Define a real workflow class and try to fetch it. This ensures the workflow registration actually works.
-        """
+        """Define a real workflow class and try to fetch it. This ensures the workflow registration actually works."""
 
         # Declare my test workflow.
         class MyWorkflow(BaseWorkflow):