chore: Adopt black formatting

.pre-commit-config.yaml

@@ -0,0 +1,7 @@
+repos:
+  - repo: https://github.com/python/black
+    rev: 19.3b0
+    hooks:
+      - id: black
+        language_version: python3.7
+        exclude_types: ['markdown', 'ini', 'toml', 'rst']

.travis.yml

@@ -21,6 +21,12 @@ matrix:
 
 install:
 # Install the code requirements
+- mkdir $HOME/bin-black
+- wget -O $HOME/bin-black/black https://github.com/python/black/releases/download/19.3b0/black
+- chmod +x $HOME/bin-black/black
+- export PATH=$PATH:$HOME/bin-black
+- black --version
+
 - make init
 
 # Install Docs requirements

DEVELOPMENT_GUIDE.rst

@@ -26,8 +26,23 @@ Setup Python locally using `pyenv`_
 #. ``pyenv install 2.7.14``
 #. Make the Python version available in the project: ``pyenv local 2.7.14``
 
+2. Install Additional Tooling
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+1. Black
+~~~~~~~~
+We format our code using [Black](https://github.com/python/black) and verify the source code is black compliant
+in Appveyor during PRs. You can find installation instructions on [Black's docs](https://black.readthedocs.io/en/stable/installation_and_usage.html).
 
-2. Activate Virtualenv
+After installing, you can run our formatting through our Makefile by `make black-format` or integrating Black directly in your favorite IDE (instructions
+can be found [here](https://black.readthedocs.io/en/stable/editor_integration.html))
+
+Pre-commit
+~~~~~~~~~~
+If you don't wish to manually run black on each pr or install black manually, we have integrated black into git hooks through [pre-commit](https://pre-commit.com/).
+After installing pre-commit, run `pre-commit install` in the root of the project. This will install black for you and run the black formatting on
+commit.
+
+3. Activate Virtualenv
 ~~~~~~~~~~~~~~~~~~~~~~
 Virtualenv allows you to install required libraries outside of the Python installation. A good practice is to setup
 a different virtualenv for each project. `pyenv`_ comes with a handy plugin that can create virtualenv.
@@ -37,7 +52,7 @@ a different virtualenv for each project. `pyenv`_ comes with a handy plugin that
 #. [Optional] Automatically activate the virtualenv in for this folder: ``pyenv local samtranslator27``
 
 
-3. Install dependencies
+4. Install dependencies
 ~~~~~~~~~~~~~~~~~~~~~~~
 Install dependencies by running the following command. Make sure the Virtualenv you created above is active.
 

Makefile

@@ -39,19 +39,21 @@ init:
 	$(info [*] Install requirements...)
 	@pip install -r requirements/dev.txt -r requirements/base.txt
 
-flake:
-	$(info [*] Running flake8...)
-	@flake8 samtranslator
-
 test:
 	$(info [*] Run the unit test with minimum code coverage of $(CODE_COVERAGE)%...)
 	@pytest --cov samtranslator --cov-report term-missing --cov-fail-under $(CODE_COVERAGE) tests
 
+black:
+	black setup.py samtranslator/* tests/* bin/*
+
+black-check:
+	black --check setup.py samtranslator/* tests/* bin/*
+
 # Command to run everytime you make changes to verify everything works
-dev: flake test
+dev: test
 
 # Verifications to run before sending a pull request
-pr: init dev
+pr: black-check init dev
 
 define HELP_MESSAGE
 
@@ -64,7 +66,6 @@ TARGETS
 	init        Initialize and install the requirements and dev-requirements for this project.
 	test        Run the Unit tests.
 	dev         Run all development tests after a change.
-	build-docs  Generate the documentation.
 	pr          Perform all checks before submitting a Pull Request.
 
 endef

bin/sam-translate.py

@@ -29,7 +29,7 @@
 from docopt import docopt
 
 my_path = os.path.dirname(os.path.abspath(__file__))
-sys.path.insert(0, my_path + '/..')
+sys.path.insert(0, my_path + "/..")
 
 from samtranslator.public.translator import ManagedPolicyLoader
 from samtranslator.translator.transform import transform
@@ -38,18 +38,19 @@
 
 LOG = logging.getLogger(__name__)
 cli_options = docopt(__doc__)
-iam_client = boto3.client('iam')
+iam_client = boto3.client("iam")
 cwd = os.getcwd()
 
-if cli_options.get('--verbose'):
+if cli_options.get("--verbose"):
     logging.basicConfig(level=logging.DEBUG)
 else:
     logging.basicConfig()
 
+
 def execute_command(command, args):
     try:
-        aws_cmd = 'aws' if platform.system().lower() != 'windows' else 'aws.cmd'
-        command_with_args = [aws_cmd, 'cloudformation', command] + list(args)
+        aws_cmd = "aws" if platform.system().lower() != "windows" else "aws.cmd"
+        command_with_args = [aws_cmd, "cloudformation", command] + list(args)
 
         LOG.debug("Executing command: %s", command_with_args)
 
@@ -63,8 +64,8 @@ def execute_command(command, args):
 
 
 def get_input_output_file_paths():
-    input_file_option = cli_options.get('--template-file')
-    output_file_option = cli_options.get('--output-template')
+    input_file_option = cli_options.get("--template-file")
+    output_file_option = cli_options.get("--output-template")
     input_file_path = os.path.join(cwd, input_file_option)
     output_file_path = os.path.join(cwd, output_file_option)
 
@@ -73,67 +74,58 @@ def get_input_output_file_paths():
 
 def package(input_file_path, output_file_path):
     template_file = input_file_path
-    package_output_template_file = input_file_path + '._sam_packaged_.yaml'
-    s3_bucket = cli_options.get('--s3-bucket')
+    package_output_template_file = input_file_path + "._sam_packaged_.yaml"
+    s3_bucket = cli_options.get("--s3-bucket")
     args = [
-        '--template-file',
+        "--template-file",
         template_file,
-        '--output-template-file',
+        "--output-template-file",
         package_output_template_file,
-        '--s3-bucket',
-        s3_bucket
+        "--s3-bucket",
+        s3_bucket,
     ]
 
-    execute_command('package', args)
+    execute_command("package", args)
 
     return package_output_template_file
 
 
 def transform_template(input_file_path, output_file_path):
-    with open(input_file_path, 'r') as f:
+    with open(input_file_path, "r") as f:
         sam_template = yaml_parse(f)
 
     try:
-        cloud_formation_template = transform(
-            sam_template, {}, ManagedPolicyLoader(iam_client))
-        cloud_formation_template_prettified = json.dumps(
-            cloud_formation_template, indent=2)
+        cloud_formation_template = transform(sam_template, {}, ManagedPolicyLoader(iam_client))
+        cloud_formation_template_prettified = json.dumps(cloud_formation_template, indent=2)
 
-        with open(output_file_path, 'w') as f:
+        with open(output_file_path, "w") as f:
             f.write(cloud_formation_template_prettified)
 
-        print('Wrote transformed CloudFormation template to: ' + output_file_path)
+        print ("Wrote transformed CloudFormation template to: " + output_file_path)
     except InvalidDocumentException as e:
-        errorMessage = reduce(lambda message, error: message + ' ' + error.message, e.causes, e.message)
+        errorMessage = reduce(lambda message, error: message + " " + error.message, e.causes, e.message)
         LOG.error(errorMessage)
         errors = map(lambda cause: cause.message, e.causes)
         LOG.error(errors)
 
 
 def deploy(template_file):
-    capabilities = cli_options.get('--capabilities')
-    stack_name = cli_options.get('--stack-name')
-    args = [
-        '--template-file',
-        template_file,
-        '--capabilities',
-        capabilities,
-        '--stack-name',
-        stack_name
-    ]
+    capabilities = cli_options.get("--capabilities")
+    stack_name = cli_options.get("--stack-name")
+    args = ["--template-file", template_file, "--capabilities", capabilities, "--stack-name", stack_name]
 
-    execute_command('deploy', args)
+    execute_command("deploy", args)
 
     return package_output_template_file
 
 
-if __name__ == '__main__':
+if __name__ == "__main__":
     input_file_path, output_file_path = get_input_output_file_paths()
 
-    if cli_options.get('package'):
+    if cli_options.get("package"):
         package_output_template_file = package(input_file_path, output_file_path)
         transform_template(package_output_template_file, output_file_path)
-    elif cli_options.get('deploy'):
+    elif cli_options.get("deploy"):
         package_output_template_file = package(input_file_path, output_file_path)
         transform_template(package_output_template_file, output_file_path)
         deploy(output_file_path)

pyproject.toml

@@ -0,0 +1,18 @@
+[tool.black]
+line-length = 120
+target_version = ['py27', 'py37', 'py36', 'py38']
+exclude = '''
+
+(
+  /(
+      \.eggs         # exclude a few common directories in the
+    | \.git          # root of the project
+    | \.tox
+    | \.venv
+    | build
+    | dist
+    | pip-wheel-metadata
+    | examples
+  )/
+)
+'''

samtranslator/__init__.py

@@ -1 +1 @@
-__version__ = '1.20.0'
+__version__ = "1.20.0"

samtranslator/intrinsics/actions.py

@@ -46,10 +46,12 @@ def can_handle(self, input_dict):
         :return: True if it matches expected structure, False otherwise
         """
 
-        return input_dict is not None \
-            and isinstance(input_dict, dict) \
-            and len(input_dict) == 1 \
+        return (
+            input_dict is not None
+            and isinstance(input_dict, dict)
+            and len(input_dict) == 1
             and self.intrinsic_name in input_dict
+        )
 
     @classmethod
     def _parse_resource_reference(cls, ref_value):
@@ -132,9 +134,7 @@ def resolve_resource_refs(self, input_dict, supported_resource_refs):
         if not resolved_value:
             return input_dict
 
-        return {
-            self.intrinsic_name: resolved_value
-        }
+        return {self.intrinsic_name: resolved_value}
 
     def resolve_resource_id_refs(self, input_dict, supported_resource_id_refs):
         """
@@ -161,9 +161,7 @@ def resolve_resource_id_refs(self, input_dict, supported_resource_id_refs):
         if not resolved_value:
             return input_dict
 
-        return {
-            self.intrinsic_name: resolved_value
-        }
+        return {self.intrinsic_name: resolved_value}
 
 
 class SubAction(Action):
@@ -372,16 +370,18 @@ def handler_method(full_ref, ref_value):
         """
 
         # RegExp to find pattern "${logicalId.property}" and return the word inside bracket
-        logical_id_regex = '[A-Za-z0-9\.]+|AWS::[A-Z][A-Za-z]*'
-        ref_pattern = re.compile(r'\$\{(' + logical_id_regex + ')\}')
+        logical_id_regex = "[A-Za-z0-9\.]+|AWS::[A-Z][A-Za-z]*"
+        ref_pattern = re.compile(r"\$\{(" + logical_id_regex + ")\}")
 
         # Find all the pattern, and call the handler to decide how to substitute them.
         # Do the substitution and return the final text
-        return re.sub(ref_pattern,
-                      # Pass the handler entire string ${logicalId.property} as first parameter and "logicalId.property"
-                      # as second parameter. Return value will be substituted
-                      lambda match: handler_method(match.group(0), match.group(1)),
-                      text)
+        return re.sub(
+            ref_pattern,
+            # Pass the handler entire string ${logicalId.property} as first parameter and "logicalId.property"
+            # as second parameter. Return value will be substituted
+            lambda match: handler_method(match.group(0), match.group(1)),
+            text,
+        )
 
 
 class GetAttAction(Action):
@@ -427,10 +427,14 @@ def resolve_resource_refs(self, input_dict, supported_resource_refs):
         if not isinstance(value, list) or len(value) < 2:
             return input_dict
 
-        if (not all(isinstance(entry, string_types) for entry in value)):
+        if not all(isinstance(entry, string_types) for entry in value):
             raise InvalidDocumentException(
-                [InvalidTemplateException('Invalid GetAtt value {}. GetAtt expects an array with 2 strings.'
-                                          .format(value))])
+                [
+                    InvalidTemplateException(
+                        "Invalid GetAtt value {}. GetAtt expects an array with 2 strings.".format(value)
+                    )
+                ]
+            )
 
         # Value of GetAtt is an array. It can contain any number of elements, with first being the LogicalId of
         # resource and rest being the attributes. In a SAM template, a reference to a resource can be used in the
@@ -515,6 +519,7 @@ class FindInMapAction(Action):
     """
     This action can't be used along with other actions.
     """
+
     intrinsic_name = "Fn::FindInMap"
 
     def resolve_parameter_refs(self, input_dict, parameters):
@@ -535,21 +540,29 @@ def resolve_parameter_refs(self, input_dict, parameters):
         # FindInMap expects an array with 3 values
         if not isinstance(value, list) or len(value) != 3:
             raise InvalidDocumentException(
-                [InvalidTemplateException('Invalid FindInMap value {}. FindInMap expects an array with 3 values.'
-                                          .format(value))])
+                [
+                    InvalidTemplateException(
+                        "Invalid FindInMap value {}. FindInMap expects an array with 3 values.".format(value)
+                    )
+                ]
+            )
 
         map_name = self.resolve_parameter_refs(value[0], parameters)
         top_level_key = self.resolve_parameter_refs(value[1], parameters)
         second_level_key = self.resolve_parameter_refs(value[2], parameters)
 
-        if not isinstance(map_name, string_types) or \
-                not isinstance(top_level_key, string_types) or \
-                not isinstance(second_level_key, string_types):
+        if (
+            not isinstance(map_name, string_types)
+            or not isinstance(top_level_key, string_types)
+            or not isinstance(second_level_key, string_types)
+        ):
             return input_dict
 
-        if map_name not in parameters or \
-                top_level_key not in parameters[map_name] or \
-                second_level_key not in parameters[map_name][top_level_key]:
+        if (
+            map_name not in parameters
+            or top_level_key not in parameters[map_name]
+            or second_level_key not in parameters[map_name][top_level_key]
+        ):
             return input_dict
 
         return parameters[map_name][top_level_key][second_level_key]