test(a2a-server): use vi.stubEnv() for env vars per GEMINI.md

[Pluviobyte]

Summary

Migrate the remaining direct process.env usage in the a2a-server tests to vi.stubEnv() / vi.unstubAllEnvs(), following the testing convention documented in GEMINI.md. Direct process.env mutation can leak state between tests. config.test.ts already follows the convention, so this completes the migration for the package.

Details

From GEMINI.md:

When testing code that depends on environment variables, use vi.stubEnv('NAME', 'value') in beforeEach and vi.unstubAllEnvs() in afterEach. Avoid modifying process.env directly as it can lead to test leakage and is less reliable. To "unset" a variable, use an empty string vi.stubEnv('NAME', '').

Changes:

• src/commands/init.test.ts: stub CODER_AGENT_WORKSPACE_PATH in beforeEach, and add an afterEach that calls vi.unstubAllEnvs().
• src/http/app.test.ts: replace the inline set/delete of CODER_AGENT_WORKSPACE_PATH with vi.stubEnv(); use an empty string when testing an unset value, matching GEMINI.md; and add vi.unstubAllEnvs() to the suite afterEach.

No production code changes.

Related Issues

Fixes #19826

How to Validate

From packages/a2a-server:

• npx vitest run src/commands/init.test.ts src/http/app.test.ts -> 25 tests pass (5 + 20).
• npx prettier --check src/commands/init.test.ts src/http/app.test.ts -> passes.
• npx eslint src/commands/init.test.ts src/http/app.test.ts -> no warnings/errors.

Pre-Merge Checklist

• Updated relevant documentation and README (if needed) — N/A
• Added/updated tests (if needed) — test-only change
• Noted breaking changes (if any) — none
• Validated on required platforms/methods:
  • MacOS
    • npm run (vitest, prettier, eslint)

[gemini-code-assist]

Summary of Changes

Hello, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request refactors test suites in the a2a-server package to align with established testing conventions. By replacing direct modifications of process.env with Vitest's stubbing utilities, the changes improve test isolation and reliability, ensuring that environment variable changes do not persist across test boundaries.

Highlights

• Environment Variable Stubbing: Replaced direct process.env mutations with vi.stubEnv() to prevent test state leakage.
• Test Cleanup: Added vi.unstubAllEnvs() to afterEach hooks to ensure a clean environment after every test execution.

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[gemini-code-assist]

Code Review

This pull request refactors the test files init.test.ts and app.test.ts to use Vitest's environment variable stubbing utilities (vi.stubEnv and vi.unstubAllEnvs) instead of directly modifying process.env. The review feedback correctly points out that, according to the repository style guide, environment variables should be unset using an empty string (e.g., vi.stubEnv('CODER_AGENT_WORKSPACE_PATH', '')) rather than passing undefined.

[gemini-code-assist]

According to the repository style guide, to "unset" an environment variable during testing, you should use an empty string vi.stubEnv('NAME', '') instead of passing undefined.

Suggested change

	vi.stubEnv('CODER_AGENT_WORKSPACE_PATH', undefined);
	vi.stubEnv('CODER_AGENT_WORKSPACE_PATH', '');

References

1. To "unset" a variable, use an empty string vi.stubEnv('NAME', ''). ^(link)

[gemini-code-assist]

According to the repository style guide, to "unset" an environment variable during testing, you should use an empty string vi.stubEnv('NAME', '') instead of passing undefined.

Suggested change

	vi.stubEnv('CODER_AGENT_WORKSPACE_PATH', undefined);
	vi.stubEnv('CODER_AGENT_WORKSPACE_PATH', '');

References

1. To "unset" a variable, use an empty string vi.stubEnv('NAME', ''). ^(link)