Fix #4236 : Add tests for AsyncResultSubject

[TanishMoral11]

Explanation

This PR adds tests for the AsyncResultSubject class. It verifies that the AsyncResultSubject handles non-iterable results correctly and ensures that the expected failures occur when the result is not iterable. The test specifically checks that the appropriate behavior is triggered when a non-iterable result is provided.

• Fixes part of #4236: Adds tests to ensure correct handling of non-iterable async results.

Essential Checklist

• The PR title and explanation each start with "Fix #bugnum: " (If this PR fixes part of an issue, prefix the title with "Fix part of #bugnum: ...".)
• Any changes to scripts/assets files have their rationale included in the PR explanation.
• The PR follows the style guide.
• The PR does not contain any unnecessary code changes from Android Studio (reference).
• The PR is made from a branch that's not called "develop" and is up-to-date with "develop".
• The PR is assigned to the appropriate reviewers (reference).

[TanishMoral11]

Hey @adhiamboperes PTAL, and suggest me if there are any changes to make.

[TanishMoral11]

Hey @adhiamboperes, PTAL !!

[github-actions]

Coverage Report

Results

Number of files assessed: 3
Overall Coverage: 89.81%
Coverage Analysis: PASS ✅

Passing coverage

Files with passing code coverage

File	Coverage	Lines Hit	Status	Min Required
MathTagHandler.kt utility/src/main/java/org/oppia/android/util/parser/html/MathTagHandler.kt	89.81%	97 / 108	✅	70%

Exempted coverage

Files exempted from coverage

File	Exemption Reason
StateRetriever.kt domain/src/main/java/org/oppia/android/domain/util/StateRetriever.kt	This file is incompatible with code coverage tooling; skipping coverage check.
AsyncResultSubject.kt testing/src/main/java/org/oppia/android/testing/data/AsyncResultSubject.kt	This file is exempted from having a test file; skipping coverage check.

Refer test_file_exemptions.textproto for the comprehensive list of file exemptions and their required coverage percentages.

To learn more, visit the Oppia Android Code Coverage wiki page