pw_presubmit: Enable mypy and get it passing

- Fix several typing issues.
- Disable type checking in several places where mypy wasn't working
  correctly.
- Enable mypy.
- Execute individual steps in the same order as they are provided with
  --step.

Change-Id: I229cf8ee39a4db5067c1923b4acfc5fcd164f733

5 files changed, 23 insertions, 15 deletions

diff --git a/pw_cli/py/pw_cli/__main__.py b/pw_cli/py/pw_cli/__main__.py
index e95c7d8ff..cf43c3235 100644
--- a/pw_cli/py/pw_cli/__main__.py
+++ b/pw_cli/py/pw_cli/__main__.py
@@ -25,6 +25,7 @@ import sys
 import logging
 import importlib
 import pkgutil
+from typing import NoReturn
 
 from pw_cli.color import colors
 import pw_cli.log
@@ -41,7 +42,7 @@ _PIGWEED_BANNER = '''
 
 
 class ArgumentParser(argparse.ArgumentParser):
-    def error(self, message: str) -> None:
+    def error(self, message: str) -> NoReturn:
         print(colors().magenta(_PIGWEED_BANNER), file=sys.stderr)
         self.print_usage(sys.stderr)
         self.exit(2, '%s: error: %s\n' % (self.prog, message))
diff --git a/pw_cli/py/pw_cli/color.py b/pw_cli/py/pw_cli/color.py
index b5ca84b71..6559def24 100644
--- a/pw_cli/py/pw_cli/color.py
+++ b/pw_cli/py/pw_cli/color.py
@@ -66,7 +66,7 @@ def colors(enabled: Optional[bool] = None) -> Union[_Color, _NoColor]:
 
     if enabled and os.name == 'nt':
         # Enable ANSI color codes in Windows cmd.exe.
-        kernel32 = ctypes.windll.kernel32
+        kernel32 = ctypes.windll.kernel32  # type: ignore
         kernel32.SetConsoleMode(kernel32.GetStdHandle(-11), 7)
 
     return _Color() if enabled else _NoColor()
diff --git a/pw_cli/py/pw_cli/envparse.py b/pw_cli/py/pw_cli/envparse.py
index da38fe37c..c65330bec 100644
--- a/pw_cli/py/pw_cli/envparse.py
+++ b/pw_cli/py/pw_cli/envparse.py
@@ -77,7 +77,9 @@ class EnvironmentParser:
     def add_var(
         self,
         name: str,
-        type: TypeConversion[T] = str,  # pylint: disable=redefined-builtin
+        # pylint: disable=redefined-builtin
+        type: TypeConversion[T] = str,  # type: ignore
+        # pylint: enable=redefined-builtin
         default: Optional[T] = None,
     ) -> None:
         """Registers an environment variable.
@@ -95,7 +97,10 @@ class EnvironmentParser:
             raise ValueError(
                 f'Variable {name} does not have prefix {self._prefix}')
 
-        self._variables[name] = VariableDescriptor(name, type, default)
+        self._variables[name] = VariableDescriptor(
+            name,
+            type,  # type: ignore
+            default)  # type: ignore
 
     def parse_env(self,
                   env: Optional[Mapping[str, str]] = None) -> EnvNamespace:
diff --git a/pw_cli/py/pw_cli/plugins.py b/pw_cli/py/pw_cli/plugins.py
index dfde79238..f2f0d3e2b 100644
--- a/pw_cli/py/pw_cli/plugins.py
+++ b/pw_cli/py/pw_cli/plugins.py
@@ -15,11 +15,10 @@
 
 import argparse
 import logging
-from typing import Callable
-from typing import NamedTuple
+from typing import Any, Callable, NamedTuple
 _LOG = logging.getLogger(__name__)
 
-DefineArgsFunction = Callable[[argparse.ArgumentParser], None]
+DefineArgsFunction = Callable[[argparse.ArgumentParser], Any]
 
 
 class Plugin(NamedTuple):
diff --git a/pw_cli/py/pw_cli/process.py b/pw_cli/py/pw_cli/process.py
index 7467df8df..cfb2d6368 100644
--- a/pw_cli/py/pw_cli/process.py
+++ b/pw_cli/py/pw_cli/process.py
@@ -29,21 +29,24 @@ _LOG = logging.getLogger(__name__)
 PW_SUBPROCESS_ENV = 'PW_SUBPROCESS'
 
 
-async def run_async(*args: str, silent: bool = False) -> int:
+async def run_async(program: str, *args: str, silent: bool = False) -> int:
     """Runs a command, capturing and logging its output.
 
     Returns the exit status of the command.
     """
 
-    command = args[0]
-    _LOG.debug('Running `%s`', shlex.join(command))
+    _LOG.debug('Running `%s`', shlex.join([program, *args]))
 
     env = os.environ.copy()
     env[PW_SUBPROCESS_ENV] = '1'
 
     stdout = asyncio.subprocess.DEVNULL if silent else asyncio.subprocess.PIPE
     process = await asyncio.create_subprocess_exec(
-        *command, stdout=stdout, stderr=asyncio.subprocess.STDOUT, env=env)
+        program,
+        *args,
+        stdout=stdout,
+        stderr=asyncio.subprocess.STDOUT,
+        env=env)
 
     if process.stdout is not None:
         while True:
@@ -57,13 +60,13 @@ async def run_async(*args: str, silent: bool = False) -> int:
 
     status = await process.wait()
     if status == 0:
-        _LOG.info('%s exited successfully', command[0])
+        _LOG.info('%s exited successfully', program)
     else:
-        _LOG.error('%s exited with status %d', command[0], status)
+        _LOG.error('%s exited with status %d', program, status)
 
     return status
 
 
-def run(*args: str, silent: bool = False) -> int:
+def run(program: str, *args: str, silent: bool = False) -> int:
     """Synchronous wrapper for run_async."""
-    return asyncio.run(run_async(args, silent))
+    return asyncio.run(run_async(program, *args, silent=silent))