Use mypy for type checking

[jacksonllee]

Add a new step to CircleCI builds for type checking by mypy. Changes needed:

• Add mypy to requirements.txt. Use whatever the latest version is from this PyPI link.
• Add a new step in .circleci/config.yml. This new step should have its name set to be Type checking, and should go just before the existing Lint step. This step should run the command mypy project/wikipron project/tests project/data.
• Fix all mypy issues so that the CircleCI builds pass with the mypy step added.
• Add an entry in CHANGELOG.md.

Guidelines for contributors

For reference, mypy 0.790 would find the following issues to be fixed across the codebase:

tests/test_data/__init__.py:23: error: The return type of a generator function should be "Generator" or one of its supertypes
tests/test_data/__init__.py:23: error: Argument 1 to "contextmanager" has incompatible type "Callable[[bool, str, str], str]"; expected "Callable[..., Iterator[<nothing>]]"
wikipron/extract/core.py:8: error: Skipping analyzing 'requests_html': found module but no type hints or library stubs
wikipron/extract/default.py:22: error: "Response" has no attribute "html"
wikipron/extract/vie.py:37: error: "Response" has no attribute "html"
wikipron/extract/tha.py:20: error: "Response" has no attribute "html"
wikipron/extract/shn.py:31: error: "Response" has no attribute "html"
wikipron/extract/lat.py:93: error: "Response" has no attribute "html"
wikipron/extract/lat.py:111: error: "Response" has no attribute "html"
wikipron/extract/lat.py:138: error: "Response" has no attribute "html"
wikipron/extract/lat.py:148: error: Incompatible types in assignment (expression has type "None", variable has type "Word")
wikipron/extract/khm.py:23: error: "Response" has no attribute "html"
wikipron/extract/khb.py:35: error: "Response" has no attribute "html"
wikipron/extract/jpn.py:41: error: "Response" has no attribute "html"
wikipron/extract/jpn.py:50: error: "Response" has no attribute "html"
wikipron/extract/cmn.py:27: error: "Response" has no attribute "html"
wikipron/config.py:8: error: Skipping analyzing 'iso639': found module but no type hints or library stubs
wikipron/config.py:9: error: Skipping analyzing 'segments': found module but no type hints or library stubs
wikipron/config.py:124: error: Incompatible return value type (got "Callable[[str], str]", expected "Callable[[Word], Word]")
wikipron/scrape.py:6: error: Skipping analyzing 'requests_html': found module but no type hints or library stubs
wikipron/scrape.py:57: error: Incompatible types in "yield" (actual type "Tuple[Any, str]", expected type "Tuple[Word, Pron]")
tests/test_wikipron/__init__.py:11: error: Argument 1 to "Config" has incompatible type "**Dict[str, str]"; expected "bool"
tests/test_wikipron/__init__.py:19: error: Module has no attribute "ConnectTimeout"
data/src/codes.py:30: error: Skipping analyzing 'iso639': found module but no type hints or library stubs
data/src/codes.py:90: error: Item "None" of "Optional[Match[Any]]" has no attribute "group"
tests/test_wikipron/test_scrape.py:3: error: Skipping analyzing 'pytest': found module but no type hints or library stubs
tests/test_wikipron/test_extract.py:1: error: Skipping analyzing 'pytest': found module but no type hints or library stubs
tests/test_wikipron/test_config.py:4: error: Skipping analyzing 'pytest': found module but no type hints or library stubs
tests/test_wikipron/test_config.py:5: error: Skipping analyzing 'requests_html': found module but no type hints or library stubs
tests/test_wikipron/test_languagecodes.py:3: error: Skipping analyzing 'iso639': found module but no type hints or library stubs
tests/test_wikipron/test_languagecodes.py:4: error: Skipping analyzing 'pytest': found module but no type hints or library stubs
tests/test_data/test_scrape.py:5: error: Skipping analyzing 'pytest': found module but no type hints or library stubs
tests/test_data/test_scrape.py:53: error: Need type annotation for 'dummy_tsv_path'
tests/test_data/test_scrape.py:54: error: Value of type "object" is not indexable
tests/test_data/test_scrape.py:57: error: Argument "config_settings" to "_build_scraping_config" has incompatible type "object"; expected "Dict[str, Any]"

[ben-fernandes-sw]

Hey @jacksonllee !
I'd like to work on this. Could you assign it to me?

[jacksonllee]

I'd like to work on this. Could you assign it to me?

Hi @benfernandes, thank you for your interest in contributing! You've been assigned. :-)

[jacksonllee]

Resolved by #247.