test: cover config loader interpolation

[saurabhhhcodes]

Summary

• add focused Jest coverage for loadConfig
• verify default config behavior when apidrift.config.json is absent
• verify ${ENV_VAR} interpolation and missing-variable fallback behavior with temp config files

Fixes #2

Validation

• git diff --check
• node --check tests/config/loader.test.js
• npm test -- --runInBand tests/config/loader.test.js could not run locally because npm is not available in this shell

GSSoC labels requested

Please add/keep gssoc and the required difficulty/type scoring labels if this is accepted.

[tanmayjoddar]

hey @saurabhhhcodes Thanks for contributing to apidrift.

Please stop opening PRs for multiple issues without discussion or assignment first.

This is creating review spam and makes contributor coordination difficult.

From now on, comment on the issue first and wait for maintainer confirmation before working on it. Unassigned or low-quality PRs may be closed without review.

[saurabhhhcodes]

Thanks for letting me know, @tanmayjoddar. I understand, and sorry for creating review pressure here.

I’ll pause opening any more PRs in this repo unless an issue is confirmed/assigned first. For the PRs already opened, please feel free to review only the ones that are useful, and I’m happy to close or adjust any of them if that would make triage easier.

[saurabhhhcodes]

Closing this older version to keep the review queue clean. The current replacement for config loader interpolation coverage is #26.