test(storage): ensure both standard localhost and Android localhost are handled

[EchoEllet]

Description

Add unit tests to ensure that partsFromHttpUrl does not return null for localhost URLs on all platforms.

The PR #7003 fixed an issue where refFromUrl returns null when the URL is localhost, which is required when connecting to the Firebase emulator of the machine. While that fix works on all platforms that use the standard localhost, it does not work on Android emulators, where the only way to connect to the machine of the emulator is by using the 127.0.0.1 address, so #12047 patched it to work on Android as well.

The PR #12047 was sent by me, and I just came across this code. I improved it a bit by:

• Adding unit tests to handle both localhost and 127.0.0.1, so adding these two unit tests while removing these two PRs will cause the tests to fail as expected.
• Refactoring the related code to improve the readability and avoid duplicating localhost and 127.0.0.1

Related Issues

• Related fix(storage, android): fix refFromUrl() when using firebase storage emulator. Essentially, check 10.0.2.2 domain as well. #12047
• Related fix(firebase_storage): fix localhost url parsing for Storage Emulator #7003

Emulators vs Firebase Emulators?

It might be confusing, but by emulators I mean Android and iOS emulators, and by Firebase emulators I mean Firebase Local Emulator Suite.

To test and use Firebase fully, only the development machine without a real Android/iOS device and a Firebase project, the emulators are used to run the mobile app, and Firebase emulators are used on the development machine for local hosting, so the apps can connect to them locally.

All platforms, including iOS simulators, desktop, and web, need localhost to connect to Firebase emulators, while Android emulators need 127.0.0.1 (special case).

Checklist

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• My PR includes unit or integration tests for all changed/updated/fixed behaviors (See Contributor Guide).
• All existing and new tests are passing.
• I updated/added relevant documentation (comments with //).
• The analyzer (melos run analyze) does not report any problems on my PR.
• I read and followed the Flutter Style Guide.
• I signed the CLA.
• I am willing to follow-up on review comments in a timely manner.

Breaking Change

• Yes, this is a breaking change.
• No, this is not a breaking change.

[SelaseKay]

Hi @EchoEllet, LGTM!

[MichaelVerdon]

Looks good to me, thanks.