This fixes a bug in the previous version where if the code does not use top level await but returns a generator or coroutine, the code would try to await it. This sometimes causes strange errors or other unexpected behaviors.

Instead, I switched to a new method of returning by raising an exception. This makes it so the coroutines produced by top level await are returned via a separate channel from return values from the code so we won't confuse them anymore.

I added a new class Executor. On creation, the Executor is given the source code and config options and produces an AST. The caller can then manipulate the AST as they see fit before calling `compile` and then `run` or `run_async`. This passes to the user the most powerful possible interface, and should make it so that Executor is helpful even in complicated use cases.

I put the main parse/compile logic into a separate generator to avoid storing any of the config options on the Executor class. This helps separate out control logic from config options and limit the scope of variables as far as possible.
ENH Improvements to eval_code. This fixes a bug in the previous version where if the code does not use top level await but returns a generator or coroutine, the code would try to await it. This sometimes causes strange errors or other unexpected behaviors.

Instead, I switched to a new method of returning by raising an exception. This makes it so the coroutines produced by top level await are returned via a separate channel from return values from the code so we won't confuse them anymore.

I added a new class Executor. On creation, the Executor is given the source code and config options and produces an AST. The caller can then manipulate the AST as they see fit before calling `compile` and then `run` or `run_async`. This passes to the user the most powerful possible interface, and should make it so that Executor is helpful even in complicated use cases.

I put the main parse/compile logic into a separate generator to avoid storing any of the config options on the Executor class. This helps separate out control logic from config options and limit the scope of variables as far as possible.
import pytest
import inspect
from typing import Callable, Dict, List, Optional, Union
import contextlib


def _run_in_pyodide_get_source(f):
    lines, start_line = inspect.getsourcelines(f)
    num_decorator_lines = 0
    for line in lines:
        if line.startswith("def"):
            break
        num_decorator_lines += 1
    start_line += num_decorator_lines - 1
    # Remove first line, which is the decorator. Then pad with empty lines to fix line number.
    lines = ["\n"] * start_line + lines[num_decorator_lines:]
    return "".join(lines)


def run_in_pyodide(
    _function: Optional[Callable] = None,
    standalone: bool = False,
    packages: List[str] = [],
    xfail_browsers: Dict[str, str] = {},
    driver_timeout: Optional[Union[str, int]] = None,
) -> Callable:
    """
    This decorator can be called in two ways --- with arguments and without
    arguments. If it is called without arguments, then the `_function` kwarg
    catches the function the decorator is applied to. Otherewise, standalone
    and packages are the actual arguments to the decorator.

    See docs/testing.md for details on how to use this.

    Parameters
    ----------
    standalone : bool, default=False
        Whether to use a standalone selenium instance to run the test or not
    packages : List[str]
        List of packages to load before running the test
    driver_timeout : Optional[Union[str, int]]
        selenium driver timeout (in seconds)
    """

    def decorator(f):
        def inner(selenium):
            if selenium.browser in xfail_browsers:
                xfail_message = xfail_browsers[selenium.browser]
                pytest.xfail(xfail_message)
            with set_webdriver_script_timeout(selenium, driver_timeout):
                if len(packages) > 0:
                    selenium.load_package(packages)
                err = None
                try:
                    # When writing the function, we set the filename to the file
                    # containing the source. This results in a more helpful
                    # traceback
                    selenium.run_js(
                        """pyodide._module.pyodide_py.eval_code.callKwargs(
                                {{
                                    code : {!r},
                                    globals : pyodide._module.globals,
                                    filename : {!r}
                                }}
                            )""".format(
                            _run_in_pyodide_get_source(f), inspect.getsourcefile(f)
                        )
                    )
                    # When invoking the function, use the default filename <eval>
                    selenium.run_js(
                        """pyodide._module.pyodide_py.eval_code("{}()", pyodide._module.globals)""".format(
                            f.__name__
                        )
                    )
                except selenium.JavascriptException as e:
                    err = e

            if err is not None:
                pytest.fail(
                    "Error running function in pyodide\n\n" + str(err),
                    pytrace=False,
                )

        if standalone:

            def wrapped_standalone(selenium_standalone):
                inner(selenium_standalone)

            return wrapped_standalone

        else:

            def wrapped(selenium):
                inner(selenium)

            return wrapped

    if _function is not None:
        return decorator(_function)
    else:
        return decorator


@contextlib.contextmanager
def set_webdriver_script_timeout(selenium, script_timeout: Optional[Union[int, float]]):
    """Set selenium script timeout

    Parameters
    ----------
    selenum : SeleniumWrapper
       a SeleniumWrapper wrapper instance
    script_timeout : int | float
       value of the timeout in seconds
    """
    if script_timeout is not None:
        selenium.driver.set_script_timeout(script_timeout)
    yield
    # revert to the initial value
    if script_timeout is not None:
        selenium.driver.set_script_timeout(selenium.script_timeout)


def parse_driver_timeout(request) -> Optional[Union[int, float]]:
    """Parse driver timeout value from pytest request object"""
    mark = request.node.get_closest_marker("driver_timeout")
    if mark is None:
        return None
    else:
        return mark.args[0]

import pytest
import inspect
from typing import Callable, Dict, List, Optional, Union
import contextlib


def _run_in_pyodide_get_source(f):
    lines, start_line = inspect.getsourcelines(f)
    num_decorator_lines = 0
    for line in lines:
        if line.startswith("def"):
            break
        num_decorator_lines += 1
    start_line += num_decorator_lines - 1
    # Remove first line, which is the decorator. Then pad with empty lines to fix line number.
    lines = ["\n"] * start_line + lines[num_decorator_lines:]
    return "".join(lines)


def run_in_pyodide(
    _function: Optional[Callable] = None,
    standalone: bool = False,
    packages: List[str] = [],
    xfail_browsers: Dict[str, str] = {},
    driver_timeout: Optional[Union[str, int]] = None,
) -> Callable:
    """
    This decorator can be called in two ways --- with arguments and without
    arguments. If it is called without arguments, then the `_function` kwarg
    catches the function the decorator is applied to. Otherewise, standalone
    and packages are the actual arguments to the decorator.

    See docs/testing.md for details on how to use this.

    Parameters
    ----------
    standalone : bool, default=False
        Whether to use a standalone selenium instance to run the test or not
    packages : List[str]
        List of packages to load before running the test
    driver_timeout : Optional[Union[str, int]]
        selenium driver timeout (in seconds)
    """

    def decorator(f):
        def inner(selenium):
            if selenium.browser in xfail_browsers:
                xfail_message = xfail_browsers[selenium.browser]
                pytest.xfail(xfail_message)
            with set_webdriver_script_timeout(selenium, driver_timeout):
                if len(packages) > 0:
                    selenium.load_package(packages)
                err = None
                try:
                    # When writing the function, we set the filename to the file
                    # containing the source. This results in a more helpful
                    # traceback
                    selenium.run_js(
                        """pyodide._module.pyodide_py.eval_code.callKwargs(
                                {{
                                    source : {!r},
                                    globals : pyodide._module.globals,
                                    filename : {!r}
                                }}
                            )""".format(
                            _run_in_pyodide_get_source(f), inspect.getsourcefile(f)
                        )
                    )
                    # When invoking the function, use the default filename <eval>
                    selenium.run_js(
                        """pyodide._module.pyodide_py.eval_code("{}()", pyodide._module.globals)""".format(
                            f.__name__
                        )
                    )
                except selenium.JavascriptException as e:
                    err = e

            if err is not None:
                pytest.fail(
                    "Error running function in pyodide\n\n" + str(err),
                    pytrace=False,
                )

        if standalone:

            def wrapped_standalone(selenium_standalone):
                inner(selenium_standalone)

            return wrapped_standalone

        else:

            def wrapped(selenium):
                inner(selenium)

            return wrapped

    if _function is not None:
        return decorator(_function)
    else:
        return decorator


@contextlib.contextmanager
def set_webdriver_script_timeout(selenium, script_timeout: Optional[Union[int, float]]):
    """Set selenium script timeout

    Parameters
    ----------
    selenum : SeleniumWrapper
       a SeleniumWrapper wrapper instance
    script_timeout : int | float
       value of the timeout in seconds
    """
    if script_timeout is not None:
        selenium.driver.set_script_timeout(script_timeout)
    yield
    # revert to the initial value
    if script_timeout is not None:
        selenium.driver.set_script_timeout(selenium.script_timeout)


def parse_driver_timeout(request) -> Optional[Union[int, float]]:
    """Parse driver timeout value from pytest request object"""
    mark = request.node.get_closest_marker("driver_timeout")
    if mark is None:
        return None
    else:
        return mark.args[0]
