Enable strict mode for mypy + other error codes

[mkniewallner]

PR Checklist

• A description of the changes is added to the description of this PR.
• If there is a related issue, make sure it is linked to this PR.
• If you've fixed a bug or added code that should be tested, add tests!
• Documentation in docs is updated

Description of changes

Enable strict mode for mypy, which enables the following flags, according to --strict documentation:

$ poetry run mypy --help | grep -A 8 "\--strict "
  --strict                  Strict mode; enables the following flags: --warn-
                            unused-configs, --disallow-any-generics,
                            --disallow-subclassing-any, --disallow-untyped-
                            calls, --disallow-untyped-defs, --disallow-
                            incomplete-defs, --check-untyped-defs, --disallow-
                            untyped-decorators, --no-implicit-optional,
                            --warn-redundant-casts, --warn-unused-ignores,
                            --warn-return-any, --no-implicit-reexport,
                            --strict-equality, --strict-concatenate

Also enable:

• warn_unreachable to warn about unreachable code
• ignore-without-code to avoid using ignore without specifying specific error codes
• redundant-expr to avoid redundant/useless expressions
• truthy-bool to avoid conditional checks where the result would always be True
• pretty to better see the location of an error reported by mypy. For instance:

deptry/json_writer.py:16: error: Missing type parameters for generic type "Dict"  [type-arg]
        def write(self, issues: Dict) -> None:
                                ^

Raw list of errors reported by mypy after activating the checks:

$ poetry run mypy
deptry/notebook_import_extractor.py:29: error: Missing type parameters for generic type "dict"  [type-arg]
        def _read_ipynb_file(path_to_ipynb: Path) -> dict:
                                                     ^
deptry/notebook_import_extractor.py:32: error: Returning Any from function declared to return "Dict[Any, Any]"  [no-any-return]
            return notebook
            ^~~~~~~~~~~~~~~
deptry/notebook_import_extractor.py:35: error: Missing type parameters for generic type "dict"  [type-arg]
        def _keep_code_cells(notebook: dict) -> List[dict]:
                                       ^
deptry/notebook_import_extractor.py:42: error: Missing type parameters for generic type "dict"  [type-arg]
        def _extract_import_statements_from_cell(self, cell: dict) -> List[str]:
                                                             ^
deptry/notebook_import_extractor.py:46: error: Missing type parameters for generic type "List"  [type-arg]
        def _flatten(list_of_lists: List[List]) -> List:
                                         ^
deptry/json_writer.py:16: error: Missing type parameters for generic type "Dict"  [type-arg]
        def write(self, issues: Dict) -> None:
                                ^
deptry/dependency.py:5: error: Module "deptry.compat" does not explicitly export attribute "PackageNotFoundError"; implicit reexport disabled  [attr-defined]
    from deptry.compat import PackageNotFoundError, metadata
    ^
deptry/module.py:7: error: Module "deptry.compat" does not explicitly export attribute "PackageNotFoundError"; implicit reexport disabled  [attr-defined]
    from deptry.compat import PackageNotFoundError, metadata
    ^
deptry/module.py:132: error: Skipping analyzing "deptry.stdlibs.py310": module is installed, but missing library stubs or py.typed marker  [import]
                    from deptry.stdlibs.py310 import stdlib
    ^
deptry/module.py:135: error: Returning Any from function declared to return "Set[str]"  [no-any-return]
                return stdlib
                ^~~~~~~~~~~~~
deptry/dependency_getter/requirements_txt.py:120: error: Missing type parameters for generic type "Match"  [type-arg]
        def _line_is_url(line: str) -> Optional[re.Match]:
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
deptry/import_parser.py:52: error: "type: ignore" comment without error code (consider "type: ignore[call-overload]" instead)  [ignore-without-code]
                    root = ast.parse(f.read(), path_to_py_file)  # type: ignore
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
deptry/import_parser.py:61: error: "type: ignore" comment without error code (consider "type: ignore[call-overload]" instead)  [ignore-without-code]
                    root = ast.parse(f.read(), path_to_py_file)  # type: ignore
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
deptry/import_parser.py:98: error: Left operand of "and" is always true  [redundant-expr]
                elif isinstance(node, ast.ImportFrom) and node.module and node.level == 0:
                     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
deptry/import_parser.py:103: error: Missing type parameters for generic type "List"  [type-arg]
        def _flatten_list(modules_per_file: List[List]) -> List:
                                                 ^
deptry/utils.py:36: error: Missing type parameters for generic type "Dict"  [type-arg]
    def load_pyproject_toml(pyproject_toml_path: str = PYPROJECT_TOML_PATH) -> Dict:
                                                                               ^
deptry/dependency_getter/pyproject_toml.py:40: error: Returning Any from function declared to return "Dict[str, Any]"  [no-any-return]
            return dependencies
            ^~~~~~~~~~~~~~~~~~~
deptry/dependency_getter/pyproject_toml.py:69: error: Missing type parameters for generic type "dict"  [type-arg]
        def _is_optional(dep: str, spec: Union[str, dict]) -> bool:
                                                    ^
deptry/dependency_getter/pyproject_toml.py:76: error: Missing type parameters for generic type "dict"  [type-arg]
        def _is_conditional(dep: str, spec: Union[str, dict]) -> bool:
                                                       ^
deptry/core.py:8: error: Skipping analyzing "deptry.dependency_getter.pyproject_toml": module is installed, but missing library stubs or py.typed marker  [import]
    from deptry.dependency_getter.pyproject_toml import PyprojectTomlDependencyGetter
    ^
deptry/core.py:8: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
deptry/core.py:9: error: Skipping analyzing "deptry.dependency_getter.requirements_txt": module is installed, but missing library stubs or py.typed marker  [import]
    from deptry.dependency_getter.requirements_txt import RequirementsTxtDependencyGetter
    ^
deptry/core.py:12: error: Skipping analyzing "deptry.issue_finders.misplaced_dev": module is installed, but missing library stubs or py.typed marker  [import]
    from deptry.issue_finders.misplaced_dev import MisplacedDevDependenciesFinder
    ^
deptry/core.py:13: error: Skipping analyzing "deptry.issue_finders.missing": module is installed, but missing library stubs or py.typed marker  [import]
    from deptry.issue_finders.missing import MissingDependenciesFinder
    ^
deptry/core.py:14: error: Skipping analyzing "deptry.issue_finders.obsolete": module is installed, but missing library stubs or py.typed marker  [import]
    from deptry.issue_finders.obsolete import ObsoleteDependenciesFinder
    ^
deptry/core.py:15: error: Skipping analyzing "deptry.issue_finders.transitive": module is installed, but missing library stubs or py.typed marker  [import]
    from deptry.issue_finders.transitive import TransitiveDependenciesFinder
    ^
deptry/cli.py:211: error: "root" has type "Path" which does not implement __bool__ or __len__ so it could always be true in boolean context  [truthy-bool]
        if not root:
               ^~~~
Found 26 errors in 10 files (checked 26 source files)

[codecov-commenter]

Codecov Report

Merging #149 (69afb8e) into main (55aa5fd) will decrease coverage by 0.1%.
The diff coverage is 96.8%.

@@           Coverage Diff           @@
##            main    #149     +/-   ##
=======================================
- Coverage   92.3%   92.2%   -0.2%     
=======================================
  Files         39      42      +3     
  Lines       1342    1348      +6     
=======================================
+ Hits        1240    1243      +3     
- Misses       102     105      +3     

Impacted Files	Coverage Δ
deptry/cli.py	73.0% <66.6%> (ø)
deptry/compat.py	71.4% <100.0%> (+4.7%)	⬆️
deptry/dependency.py	92.9% <100.0%> (ø)
deptry/dependency_getter/pyproject_toml.py	100.0% <100.0%> (ø)
deptry/dependency_getter/requirements_txt.py	96.5% <100.0%> (ø)
deptry/import_parser.py	96.7% <100.0%> (ø)
deptry/issue_finders/transitive.py	96.0% <100.0%> (+0.1%)	⬆️
deptry/json_writer.py	100.0% <100.0%> (ø)
deptry/module.py	89.7% <100.0%> (+0.1%)	⬆️
deptry/notebook_import_extractor.py	100.0% <100.0%> (ø)
... and 4 more

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[mkniewallner]

69afb8e is a good occasion to see #138 (comment) happening in the wild.