asolution.py

from __future__ import annotations
from collections.abc import Collection
from pathlib import Path
from typing import Optional, Type, Any, Literal, Union, Annotated
from typing_extensions import Self
from pydantic import ValidationError
from pydantic.fields import AliasChoices, Field
from pydantic_settings import (
    BaseSettings,
    PydanticBaseSettingsSource,
    CliSettingsSource,
)

class MyConfigSettings(BaseSettings):
    job_name: str = Field(alias=AliasChoices('JOB_NAME', 'job_name'))
    job_run_id: str = Field(alias=AliasChoices('JOB_RUN_ID', 'job_run_id'))
    workflow_name: Optional[str] = Field(default=None, alias=AliasChoices('WORKFLOW_NAME', 'workflow_name'))
    workflow_run_id: Optional[str] = Field(default=None, alias=AliasChoices('WORKFLOW_RUN_ID', 'workflow_run_id'))
      
    @classmethod
    def settings_customise_sources(
        cls,
        settings_cls: Type[BaseSettings],
        init_settings: PydanticBaseSettingsSource,
        env_settings: PydanticBaseSettingsSource,
        dotenv_settings: PydanticBaseSettingsSource,
        file_secret_settings: PydanticBaseSettingsSource,
    ) -> tuple[PydanticBaseSettingsSource, ...]:
        """
        This method overrides the default settings sources so that initially, only
        init_settings are considered.
        """
        return (init_settings,)
    
    @classmethod
    def load(cls, args: Optional[Collection[str]] = None, **kwargs: Any) -> Self:
        class WrapperConfig(cls):
            @classmethod
            def settings_customise_sources(
                cls,
                settings_cls: Type[BaseSettings],
                init_settings: PydanticBaseSettingsSource,
                env_settings: PydanticBaseSettingsSource,
                dotenv_settings: PydanticBaseSettingsSource,
                file_secret_settings: PydanticBaseSettingsSource,
            ) -> tuple[PydanticBaseSettingsSource, ...]:
                """
                Restore the sources you want
                """
                return (
                    CliSettingsSource(cli_parse_args=True, cli_ignore_unknown_args=True),
                    init_settings,
                    env_settings,
                    dotenv_settings,
                    file_secret_settings,
                )

        return WrapperConfig(**kwargs, _cli_parse_args=args)
    
    
# Following test code is now OK
def test_something_depending_on_schema():
    my_config = MyConfigSettings(
      job_name='test_job',
      job_run_id='test_job_inst_1'
    )
    something_that_needs_config(my_config)

theproblem.py

from __future__ import annotations
from typing import Optional
from pydantic.fields import AliasChoices, Field
from pydantic_settings import BaseSettings


class MyConfigSettings(BaseSettings, cli_parse_args=True):
    job_name: str = Field(alias=AliasChoices('JOB_NAME', 'job_name'))
    job_run_id: str = Field(alias=AliasChoices('JOB_RUN_ID', 'job_run_id'))
    workflow_name: Optional[str] = Field(default=None, alias=AliasChoices('WORKFLOW_NAME', 'workflow_name'))
    workflow_run_id: Optional[str] = Field(default=None, alias=AliasChoices('WORKFLOW_RUN_ID', 'workflow_run_id'))


# Following test code violates principle of least surprise, need to do DI that only Python can support
def test_something_depending_on_schema():
    my_config = MyConfigSettings(
      job_name='test_job',
      job_run_id='test_job_inst_1'
    )
    something_that_needs_config(my_config)

    
# If someone runs pytest -k depending_on_schema, there is an error because the "-k" is not supported.