Add flake8 to our test suite and fix all errors (#7379)

* Add flake8 to our test suite and fix all errors

* Add some documentation

11 files changed, 80 insertions, 83 deletions

diff --git a/lib/python/kle2xy.py b/lib/python/kle2xy.py
index 929144319..bff1d025b 100644
--- a/lib/python/kle2xy.py
+++ b/lib/python/kle2xy.py
@@ -46,7 +46,7 @@ class KLE2xy(list):
         if 'name' in properties:
             self.name = properties['name']
 
-    def parse_layout(self, layout):
+    def parse_layout(self, layout):  # noqa  FIXME(skullydazed): flake8 says this has a complexity of 25, it should be refactored.
         # Wrap this in a dictionary so hjson will parse KLE raw data
         layout = '{"layout": [' + layout + ']}'
         layout = hjson.loads(layout)['layout']
diff --git a/lib/python/qmk/cli/compile.py b/lib/python/qmk/cli/compile.py
index 5c2980009..234ffb12c 100755
--- a/lib/python/qmk/cli/compile.py
+++ b/lib/python/qmk/cli/compile.py
@@ -2,9 +2,6 @@
 
 You can compile a keymap already in the repo or using a QMK Configurator export.
 """
-import json
-import os
-import sys
 import subprocess
 from argparse import FileType
 
diff --git a/lib/python/qmk/cli/config.py b/lib/python/qmk/cli/config.py
index c4ee20cba..e17d8bb9b 100644
--- a/lib/python/qmk/cli/config.py
+++ b/lib/python/qmk/cli/config.py
@@ -1,8 +1,5 @@
 """Read and write configuration settings
 """
-import os
-import subprocess
-
 from milc import cli
 
 
@@ -12,6 +9,54 @@ def print_config(section, key):
     cli.echo('%s.%s{fg_cyan}={fg_reset}%s', section, key, cli.config[section][key])
 
 
+def show_config():
+    """Print the current configuration to stdout.
+    """
+    for section in cli.config:
+        for key in cli.config[section]:
+            print_config(section, key)
+
+
+def parse_config_token(config_token):
+    """Split a user-supplied configuration-token into its components.
+    """
+    section = option = value = None
+
+    if '=' in config_token and '.' not in config_token:
+        cli.log.error('Invalid configuration token, the key must be of the form <section>.<option>: %s', config_token)
+        return section, option, value
+
+    # Separate the key (<section>.<option>) from the value
+    if '=' in config_token:
+        key, value = config_token.split('=')
+    else:
+        key = config_token
+
+    # Extract the section and option from the key
+    if '.' in key:
+        section, option = key.split('.', 1)
+    else:
+        section = key
+
+    return section, option, value
+
+
+def set_config(section, option, value):
+    """Set a config key in the running config.
+    """
+    log_string = '%s.%s{fg_cyan}:{fg_reset} %s {fg_cyan}->{fg_reset} %s'
+    if cli.args.read_only:
+        log_string += ' {fg_red}(change not written)'
+
+    cli.echo(log_string, section, option, cli.config[section][option], value)
+
+    if not cli.args.read_only:
+        if value == 'None':
+            del cli.config[section][option]
+        else:
+            cli.config[section][option] = value
+
+
 @cli.argument('-ro', '--read-only', arg_only=True, action='store_true', help='Operate in read-only mode.')
 @cli.argument('configs', nargs='*', arg_only=True, help='Configuration options to read or write.')
 @cli.subcommand("Read and write configuration settings.")
@@ -33,12 +78,7 @@ def config(cli):
     No validation is done to ensure that the supplied section.key is actually used by qmk scripts.
     """
     if not cli.args.configs:
-        # Walk the config tree
-        for section in cli.config:
-            for key in cli.config[section]:
-                print_config(section, key)
-
-        return True
+        return show_config()
 
     # Process config_tokens
     save_config = False
@@ -46,43 +86,23 @@ def config(cli):
     for argument in cli.args.configs:
         # Split on space in case they quoted multiple config tokens
         for config_token in argument.split(' '):
-            # Extract the section, config_key, and value to write from the supplied config_token.
-            if '=' in config_token:
-                key, value = config_token.split('=')
-            else:
-                key = config_token
-                value = None
-
-            if '.' in key:
-                section, config_key = key.split('.', 1)
-            else:
-                section = key
-                config_key = None
+            section, option, value = parse_config_token(config_token)
 
             # Validation
-            if config_key and '.' in config_key:
-                cli.log.error('Config keys may not have more than one period! "%s" is not valid.', key)
+            if option and '.' in option:
+                cli.log.error('Config keys may not have more than one period! "%s" is not valid.', config_token)
                 return False
 
             # Do what the user wants
-            if section and config_key and value:
-                # Write a config key
-                log_string = '%s.%s{fg_cyan}:{fg_reset} %s {fg_cyan}->{fg_reset} %s'
-                if cli.args.read_only:
-                    log_string += ' {fg_red}(change not written)'
-
-                cli.echo(log_string, section, config_key, cli.config[section][config_key], value)
-
+            if section and option and value:
+                # Write a configuration option
+                set_config(section, option, value)
                 if not cli.args.read_only:
-                    if value == 'None':
-                        del cli.config[section][config_key]
-                    else:
-                        cli.config[section][config_key] = value
                     save_config = True
 
-            elif section and config_key:
+            elif section and option:
                 # Display a single key
-                print_config(section, config_key)
+                print_config(section, option)
 
             elif section:
                 # Display an entire section
diff --git a/lib/python/qmk/cli/doctor.py b/lib/python/qmk/cli/doctor.py
index c2723bfcb..1010eafb3 100755
--- a/lib/python/qmk/cli/doctor.py
+++ b/lib/python/qmk/cli/doctor.py
@@ -2,11 +2,9 @@
 
 Check up for QMK environment.
 """
-import os
 import platform
 import shutil
 import subprocess
-from glob import glob
 
 from milc import cli
 
diff --git a/lib/python/qmk/cli/flash.py b/lib/python/qmk/cli/flash.py
index 37556aaaf..031cb9496 100644
--- a/lib/python/qmk/cli/flash.py
+++ b/lib/python/qmk/cli/flash.py
@@ -3,17 +3,11 @@
 You can compile a keymap already in the repo or using a QMK Configurator export.
 A bootloader must be specified.
 """
-import os
-import sys
 import subprocess
-from argparse import FileType
-
-from milc import cli
-from qmk.commands import create_make_command
-from qmk.commands import parse_configurator_json
-from qmk.commands import compile_configurator_json
 
 import qmk.path
+from milc import cli
+from qmk.commands import compile_configurator_json, create_make_command, parse_configurator_json
 
 
 def print_bootloader_help():
diff --git a/lib/python/qmk/cli/json/keymap.py b/lib/python/qmk/cli/json/keymap.py
index 7b7553104..a030ab53d 100755
--- a/lib/python/qmk/cli/json/keymap.py
+++ b/lib/python/qmk/cli/json/keymap.py
@@ -2,7 +2,6 @@
 """
 import json
 import os
-import sys
 
 from milc import cli
 
diff --git a/lib/python/qmk/cli/kle2json.py b/lib/python/qmk/cli/kle2json.py
index 5a4e97e3a..00f63d362 100755
--- a/lib/python/qmk/cli/kle2json.py
+++ b/lib/python/qmk/cli/kle2json.py
@@ -1,10 +1,8 @@
 """Convert raw KLE to JSON
-
 """
 import json
 import os
 from pathlib import Path
-from argparse import FileType
 from decimal import Decimal
 from collections import OrderedDict
 
@@ -23,7 +21,7 @@ class CustomJSONEncoder(json.JSONEncoder):
                 return float(obj)
         except TypeError:
             pass
-        return JSONEncoder.default(self, obj)
+        return json.JSONEncoder.default(self, obj)
 
 
 @cli.argument('filename', help='The KLE raw txt to convert')
diff --git a/lib/python/qmk/cli/list/keyboards.py b/lib/python/qmk/cli/list/keyboards.py
index 2a29ccb14..76e7760e8 100644
--- a/lib/python/qmk/cli/list/keyboards.py
+++ b/lib/python/qmk/cli/list/keyboards.py
@@ -1,27 +1,27 @@
 """List the keyboards currently defined within QMK
 """
 import os
-import re
 import glob
 
 from milc import cli
 
+BASE_PATH = os.path.join(os.getcwd(), "keyboards") + os.path.sep
+KB_WILDCARD = os.path.join(BASE_PATH, "**", "rules.mk")
+
+
+def find_name(path):
+    """Determine the keyboard name by stripping off the base_path and rules.mk.
+    """
+    return path.replace(BASE_PATH, "").replace(os.path.sep + "rules.mk", "")
+
 
 @cli.subcommand("List the keyboards currently defined within QMK")
 def list_keyboards(cli):
     """List the keyboards currently defined within QMK
     """
-
-    base_path = os.path.join(os.getcwd(), "keyboards") + os.path.sep
-    kb_path_wildcard = os.path.join(base_path, "**", "rules.mk")
-
     # find everywhere we have rules.mk where keymaps isn't in the path
-    paths = [path for path in glob.iglob(kb_path_wildcard, recursive=True) if 'keymaps' not in path]
-
-    # strip the keyboard directory path prefix and rules.mk suffix and alphabetize
-    find_name = lambda path: path.replace(base_path, "").replace(os.path.sep + "rules.mk", "")
-    names = sorted(map(find_name, paths))
+    paths = [path for path in glob.iglob(KB_WILDCARD, recursive=True) if 'keymaps' not in path]
 
-    for name in names:
-        # We echo instead of cli.log.info to allow easier piping of this output
-        cli.echo(name)
+    # Extract the keyboard name from the path and print it
+    for keyboard_name in sorted(map(find_name, paths)):
+        print(keyboard_name)
diff --git a/lib/python/qmk/cli/pytest.py b/lib/python/qmk/cli/pytest.py
index 14613e1d9..09611d750 100644
--- a/lib/python/qmk/cli/pytest.py
+++ b/lib/python/qmk/cli/pytest.py
@@ -2,19 +2,15 @@
 
 QMK script to run unit and integration tests against our python code.
 """
-import sys
+import subprocess
+
 from milc import cli
 
 
 @cli.subcommand('QMK Python Unit Tests')
 def pytest(cli):
-    """Use nose2 to run unittests
+    """Run several linting/testing commands.
     """
-    try:
-        import nose2
-
-    except ImportError:
-        cli.log.error('Could not import nose2! Please install it with {fg_cyan}pip3 install nose2')
-        return False
-
-    nose2.discover(argv=['nose2', '-v'])
+    flake8 = subprocess.run(['flake8', 'lib/python', 'bin/qmk'])
+    nose2 = subprocess.run(['nose2', '-v'])
+    return flake8.returncode | nose2.returncode
diff --git a/lib/python/qmk/keymap.py b/lib/python/qmk/keymap.py
index 396b53a6f..f4a2893f3 100644
--- a/lib/python/qmk/keymap.py
+++ b/lib/python/qmk/keymap.py
@@ -1,12 +1,8 @@
 """Functions that help you work with QMK keymaps.
 """
-import json
-import logging
 import os
-from traceback import format_exc
 
 import qmk.path
-from qmk.errors import NoSuchKeyboardError
 
 # The `keymap.c` template to use when a keyboard doesn't have its own
 DEFAULT_KEYMAP_C = """#include QMK_KEYBOARD_H
diff --git a/lib/python/qmk/path.py b/lib/python/qmk/path.py
index 2149625cc..cf087265f 100644
--- a/lib/python/qmk/path.py
+++ b/lib/python/qmk/path.py
@@ -2,7 +2,6 @@
 """
 import logging
 import os
-from pkgutil import walk_packages
 
 from qmk.errors import NoSuchKeyboardError