test(emulators): replace 2s sleep delays in import-export tests with active port polling

[joehan]

Description

Replaces hardcoded 2-second setTimeout sleep delays across the 10 end-to-end import/export test cases in scripts/emulator-import-export-tests/tests.ts with an active port release polling helper (waitForPortClosed).

Motivation & Background

• Parent Goal: http://b/563410897 ([Goal] Improve the speed and reliability of the integration test suite)
• Buganizer Task: http://b/563476956 ([Task] Replace arbitrary 2s sleep delays in import-export tests with active port polling)
• Previously, tests.ts used await new Promise((resolve) => setTimeout(resolve, 2000)); at the start of every test to give previously stopped emulator subprocesses time to release their listening ports.
• This introduced 20 seconds of hardcoded dead time per test run. Furthermore, on slower runners (such as Windows CI), 2 seconds was intermittently insufficient for the OS socket stack to fully release port 4000 (hub) and service emulator ports, causing EADDRINUSE collisions that led maintainers to disable test:import-export in Windows CI (.github/workflows/node-test.yml L266).

Changes

1. Added waitForPortClosed(port: number, host?: string, timeoutMs: number = 10000): Promise<void> in scripts/emulator-import-export-tests/tests.ts using tcp-port-used.waitUntilFreeOnHost with 50ms polling interval and dual-stack localhost/127.0.0.1 verification. Errors are wrapped in FirebaseError with original error details preserved.
2. Replaced the 10 blind 2-second sleep delays across the suite with parallel active polling of the hub port and target emulator ports before starting new CLIProcess instances.
3. Tests now proceed immediately when ports are released (typically 20-50ms), saving ~18-20 seconds per run while eliminating port collision race conditions.

Verification

• npm run test:compile: Passed with 0 errors.
• npx eslint scripts/emulator-import-export-tests/tests.ts: Passed with 0 errors.
• Verified active polling resolves in ~43ms when ports are free and emulator test cases pass cleanly.

[gemini-code-assist]

Code Review

This pull request improves the reliability of the emulator import/export integration tests by replacing arbitrary 2-second delays with a helper function, waitForPortClosed, which polls until the required emulator ports are released. The reviewer feedback correctly points out a violation of the repository's style guide regarding strict null checks, recommending that the emulator configuration be validated once at the top level to avoid using the non-null assertion operator (!) repeatedly across the test cases.

[gemini-code-assist]

According to the repository style guide, we should use strict null checks and handle undefined/null explicitly instead of using non-null assertions (!). Since CONFIG.emulators is optional, we should validate its presence once at the top level and throw a FirebaseError with a non-zero exit code if it is missing. This allows us to safely access EMULATORS without using the non-null assertion operator (!) in every test case.

const CONFIG = readConfig();
if (!CONFIG.emulators) {
  throw new FirebaseError("Emulator configuration is missing in firebase.json", { exit: 1 });
}
const EMULATORS = CONFIG.emulators;

References

1. Use strict null checks and handle undefined/null explicitly. ^(link)
2. Throw FirebaseError for expected, user-facing errors. If the error is due to a violation of a precondition, specify a non-zero exit code. ^(link)

[gemini-code-assist]

Use the validated EMULATORS constant instead of CONFIG.emulators! to adhere to the repository style guide's rule of handling undefined/null explicitly.

    await Promise.all([
      waitForPortClosed(EMULATORS.hub.port),
      waitForPortClosed(EMULATORS.firestore.port),
    ]);

References

1. Use strict null checks and handle undefined/null explicitly. ^(link)

[gemini-code-assist]

Use the validated EMULATORS constant instead of CONFIG.emulators! to adhere to the repository style guide's rule of handling undefined/null explicitly.

    await Promise.all([
      waitForPortClosed(EMULATORS.hub.port),
      waitForPortClosed(EMULATORS.database.port),
    ]);

References

1. Use strict null checks and handle undefined/null explicitly. ^(link)

[gemini-code-assist]

Use the validated EMULATORS constant instead of CONFIG.emulators! to adhere to the repository style guide's rule of handling undefined/null explicitly.

    await Promise.all([
      waitForPortClosed(EMULATORS.hub.port),
      waitForPortClosed(EMULATORS.auth.port),
    ]);

References

1. Use strict null checks and handle undefined/null explicitly. ^(link)

[gemini-code-assist]

Use the validated EMULATORS constant instead of CONFIG.emulators! to adhere to the repository style guide's rule of handling undefined/null explicitly.

    await Promise.all([
      waitForPortClosed(EMULATORS.hub.port),
      waitForPortClosed(EMULATORS.auth.port),
    ]);

References

1. Use strict null checks and handle undefined/null explicitly. ^(link)

[gemini-code-assist]

Use the validated EMULATORS constant instead of CONFIG.emulators! to adhere to the repository style guide's rule of handling undefined/null explicitly.

    await Promise.all([
      waitForPortClosed(EMULATORS.hub.port),
      waitForPortClosed(EMULATORS.auth.port),
    ]);

References

1. Use strict null checks and handle undefined/null explicitly. ^(link)

[gemini-code-assist]

Use the validated EMULATORS constant instead of CONFIG.emulators! to adhere to the repository style guide's rule of handling undefined/null explicitly.

    await Promise.all([
      waitForPortClosed(EMULATORS.hub.port),
      waitForPortClosed(EMULATORS.storage.port),
    ]);

References

1. Use strict null checks and handle undefined/null explicitly. ^(link)

[gemini-code-assist]

Use the validated EMULATORS constant instead of CONFIG.emulators! to adhere to the repository style guide's rule of handling undefined/null explicitly.

    await Promise.all([
      waitForPortClosed(EMULATORS.hub.port),
      waitForPortClosed(EMULATORS.storage.port),
      waitForPortClosed(EMULATORS.auth.port),
    ]);

References

1. Use strict null checks and handle undefined/null explicitly. ^(link)

[gemini-code-assist]

Use the validated EMULATORS constant instead of CONFIG.emulators! to adhere to the repository style guide's rule of handling undefined/null explicitly.

    await Promise.all([
      waitForPortClosed(EMULATORS.hub.port),
      waitForPortClosed(EMULATORS.storage.port),
      waitForPortClosed(EMULATORS.auth.port),
    ]);

References

1. Use strict null checks and handle undefined/null explicitly. ^(link)

[gemini-code-assist]

Use the validated EMULATORS constant instead of CONFIG.emulators! to adhere to the repository style guide's rule of handling undefined/null explicitly.

    await Promise.all([
      waitForPortClosed(EMULATORS.hub.port),
      waitForPortClosed(EMULATORS.firestore.port),
    ]);

References

1. Use strict null checks and handle undefined/null explicitly. ^(link)