test: add unit tests for retryWithBackoff

[sapnilbiswas]

Summary

This PR adds a comprehensive Jest test suite for the js/utils/retryWithBackoff.js module, which handles race conditions (like waiting for container bounds) using an exponential backoff strategy. This previously untested file now has 100% test coverage (statements, branches, functions, and lines).

What changed

• Added: js/utils/__tests__/retryWithBackoff.test.js — New Jest test file for testing the backoff and retry behavior.

Test coverage

• Immediate Resolution: Verifies that if check() returns truthy on the first try, it resolves immediately without triggering any delay timeouts.
• Exponential Backoff Scaling: Ensures the delay correctly scales exponentially between attempts (initialDelay * 2^attempt).
• Retry Exhaustion: Checks that exceeding maxRetries properly halts execution and throws an Error with the provided (or default) errorMessage.
• Side-effects Callback (onRetry): Asserts that the optional onRetry callback is invoked with the correct attempt index on each failure.
• Default Arguments & Fallbacks: Ensures fallback to the default Promise-wrapped setTimeout when a custom delayFn is omitted, and tests the default maxRetries (20) and initialDelay (50) values.

How it is tested

• Mocking: Used jest.fn() to mock the check(), onSuccess(), onRetry(), and delayFn() functions to strictly verify invocation counts and arguments.
• Simulating State Changes: Utilized .mockReturnValueOnce() to simulate check() initially failing (returning falsy values) before eventually succeeding on later attempts to test the retry loop.
• Fake Timers: For testing the default delayFn (which uses standard setTimeout), jest.useFakeTimers() and jest.advanceTimersByTime() were used to advance the clock instantly, ensuring the tests remain fast and deterministic without actual asynchronous waiting.
• Error Handling: Used Jest's .rejects.toThrow() to validate that the correct error boundaries are hit when the maximum number of retries is exceeded.

PR Category

• Tests

[github-actions]

🧪 Jest Test Results

✅ All Jest tests passed! This PR is ready to merge.

Coverage: Statements: 47.58% | Branches: 38.82% | Functions: 52.5% | Lines: 47.98%
Master Coverage: Statements: 48.09% | Branches: 39.61% | Functions: 52.88% | Lines: 48.49%

[sapnilbiswas]

@walterbender PLease have a look when you get time

[mahesh-09-12]

Tested locally - the added tests cover the retry, backoff, and failure scenarios well.

[Ashutoshx7]

why a separate file when we already have one on master ?

need changes

[walterbender]

Please see the comment by Ahsutosh

[Ashutoshx7]

checking in again for any updates @sapnilbiswas

[sapnilbiswas]

@Ashutoshx7 I apologize for being this late in responding, I was actually going through some end-sem exams and was unable to keep on working on it. I will be back to contributing in a week.

[Ashutoshx7]

@Ashutoshx7 I apologize for being this late in responding, I was actually going through some end-sem exams and was unable to keep on working on it. I will be back to contributing in a week.

Ya sure
Its fine
I should have waited a bit more
Take ur time
And best of luck for your exams

[github-actions]

This PR has merge conflicts with master.

Please rebase your branch:

# Add upstream remote (one-time setup)
git remote add upstream https://github.com/sugarlabs/musicblocks.git

# Fetch latest master and rebase
git fetch upstream
git rebase upstream/master

# Resolve any conflicts, then:
git push --force-with-lease origin YOUR_BRANCH

Tip: Enable "Allow edits from maintainers" on this PR so we can auto-rebase for you next time. This only grants access to your PR branch. Your fork's other branches are not affected.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 58.38%. Comparing base (84e8052) to head (b43de39).

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #7446   +/-   ##
=======================================
  Coverage   58.38%   58.38%           
=======================================
  Files         174      174           
  Lines       57894    57894           
=======================================
+ Hits        33800    33802    +2     
+ Misses      24094    24092    -2     

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