In the discussion on #328 the consensus seems to be that people like type definitions. This moves toward generating types using jsdoc as suggested by @bollwyvl in that thread.

I don't have much Typescript experience so I would very much appreciate it if people could test them out. The types are available as CircleCI artifacts here:
https://3914-322074228-gh.circle-artifacts.com/0/root/repo/build/pyodide.d.ts

@bollwyvl said that

> types that aren't tested are probably worse than no types at all

If anyone could contribute tests, that would be very helpful (I don't know what they should look like). 

The main limitation I ran into with this approach is that Typescript supports Typescript types in jsdoc annotations but jsdoc does not. This means that if we want to automatically generate docs, we have to stick to the much more limited syntax that jsdoc supports. For example, `isPyProxy` should be typed `obj is PyProxy` but this approach does not allow that as far as I can tell. 
Some basic types. In the discussion on #328 the consensus seems to be that people like type definitions. This moves toward generating types using jsdoc as suggested by @bollwyvl in that thread.

I don't have much Typescript experience so I would very much appreciate it if people could test them out. The types are available as CircleCI artifacts here:
https://3914-322074228-gh.circle-artifacts.com/0/root/repo/build/pyodide.d.ts

@bollwyvl said that

> types that aren't tested are probably worse than no types at all

If anyone could contribute tests, that would be very helpful (I don't know what they should look like). 

The main limitation I ran into with this approach is that Typescript supports Typescript types in jsdoc annotations but jsdoc does not. This means that if we want to automatically generate docs, we have to stick to the much more limited syntax that jsdoc supports. For example, `isPyProxy` should be typed `obj is PyProxy` but this approach does not allow that as far as I can tell. 
import pytest
import os
from pathlib import Path
from pyodide_build.common import _parse_package_subset
from pyodide_build.io import parse_package_config

PKG_DIR = Path(__file__).parent


def registered_packages():
    """Returns a list of registered package names"""
    packages = []
    for name in os.listdir(PKG_DIR):
        if (PKG_DIR / name).is_dir() and (PKG_DIR / name / "meta.yaml").exists():
            packages.append(name)
    return packages


def registered_packages_meta():
    """Returns a dictionary with the contents of `meta.yaml`
    for each registered package
    """
    packages = registered_packages
    return {
        name: parse_package_config(PKG_DIR / name / "meta.yaml") for name in packages
    }


UNSUPPORTED_PACKAGES: dict = {"chrome": [], "firefox": []}


@pytest.mark.parametrize("name", registered_packages())
def test_parse_package(name):
    # check that we can parse the meta.yaml
    meta = parse_package_config(PKG_DIR / name / "meta.yaml")

    skip_host = meta.get("build", {}).get("skip_host", True)
    if name == "numpy":
        assert skip_host is False
    elif name == "pandas":
        assert skip_host is True


@pytest.mark.skip_refcount_check
@pytest.mark.driver_timeout(40)
@pytest.mark.parametrize("name", registered_packages())
def test_import(name, selenium_standalone):
    # check that we can parse the meta.yaml
    meta = parse_package_config(PKG_DIR / name / "meta.yaml")

    if name in UNSUPPORTED_PACKAGES[selenium_standalone.browser]:
        pytest.xfail(
            "{} fails to load and is not supported on {}.".format(
                name, selenium_standalone.browser
            )
        )

    built_packages = _parse_package_subset(os.environ.get("PYODIDE_PACKAGES"))
    # only a subset of packages were built
    if built_packages is not None and name not in built_packages:
        pytest.skip(f"{name} was skipped due to PYODIDE_PACKAGES")

    selenium_standalone.run("import glob, os")

    baseline_pyc = selenium_standalone.run(
        """
        len(list(glob.glob(
            '/lib/python3.8/site-packages/**/*.pyc',
            recursive=True)
        ))
        """
    )
    for import_name in meta.get("test", {}).get("imports", []):
        selenium_standalone.run_async("import %s" % import_name)
        # Make sure that even after importing, there are no additional .pyc
        # files
        assert (
            selenium_standalone.run(
                """
            len(list(glob.glob(
                '/lib/python3.8/site-packages/**/*.pyc',
                recursive=True)
            ))
            """
            )
            == baseline_pyc
        )

import pytest
import os
from pathlib import Path
from pyodide_build.common import _parse_package_subset
from pyodide_build.io import parse_package_config

PKG_DIR = Path(__file__).parent


def registered_packages():
    """Returns a list of registered package names"""
    packages = []
    for name in os.listdir(PKG_DIR):
        if (PKG_DIR / name).is_dir() and (PKG_DIR / name / "meta.yaml").exists():
            packages.append(name)
    return packages


def registered_packages_meta():
    """Returns a dictionary with the contents of `meta.yaml`
    for each registered package
    """
    packages = registered_packages
    return {
        name: parse_package_config(PKG_DIR / name / "meta.yaml") for name in packages
    }


UNSUPPORTED_PACKAGES: dict = {"chrome": [], "firefox": []}


@pytest.mark.parametrize("name", registered_packages())
def test_parse_package(name):
    # check that we can parse the meta.yaml
    meta = parse_package_config(PKG_DIR / name / "meta.yaml")

    skip_host = meta.get("build", {}).get("skip_host", True)
    if name == "numpy":
        assert skip_host is False
    elif name == "pandas":
        assert skip_host is True


@pytest.mark.skip_refcount_check
@pytest.mark.driver_timeout(40)
@pytest.mark.parametrize("name", registered_packages())
def test_import(name, selenium_standalone):
    # check that we can parse the meta.yaml
    meta = parse_package_config(PKG_DIR / name / "meta.yaml")

    if name in UNSUPPORTED_PACKAGES[selenium_standalone.browser]:
        pytest.xfail(
            "{} fails to load and is not supported on {}.".format(
                name, selenium_standalone.browser
            )
        )

    built_packages = _parse_package_subset(os.environ.get("PYODIDE_PACKAGES"))
    # only a subset of packages were built
    if built_packages is not None and name not in built_packages:
        pytest.skip(f"{name} was skipped due to PYODIDE_PACKAGES")

    selenium_standalone.run("import glob, os")

    baseline_pyc = selenium_standalone.run(
        """
        len(list(glob.glob(
            '/lib/python3.8/site-packages/**/*.pyc',
            recursive=True)
        ))
        """
    )
    for import_name in meta.get("test", {}).get("imports", []):
        selenium_standalone.run_async("import %s" % import_name)
        # Make sure that even after importing, there are no additional .pyc
        # files
        assert (
            selenium_standalone.run(
                """
            len(list(glob.glob(
                '/lib/python3.8/site-packages/**/*.pyc',
                recursive=True)
            ))
            """
            )
            == baseline_pyc
        )
