test(logo): improve unit test coverage for Logo execution engine

[vanshika2720]

Summary

This PR improves the unit test coverage for logo.js by adding comprehensive tests for previously untested logic and important edge cases. No production code is modified.

Changes Made

Added tests for safePluginExecute()

• Successful function execution
• Error handling and recovery
• Unary, binary, and constant math plugin patterns
• Parameter plugin pattern
• Arbitrary code execution rejection

Expanded parseArg() coverage

• dectofrac with null and non-number child values
• Hue block outside status matrix
• returnValue with empty and populated stacks
• evalArgDict dispatch
• Unknown block fallback handling

Added dispatchTurtleSignals() tests

• All dispatch factor threshold branches:
  • > 100
  • > 50
  • > 25
  • > 12.5
  • ≤ 12.5
• Zero-step-time clamping

Added timer manager tests

• Getter behavior
• clearAll()
• getStats()
• setGuardedTimeout() when:
  • guard allows execution
  • guard suppresses execution

Added doStopTurtles() tests

• Delayed timeout cleanup
• Timer manager cleanup
• Debug logging when timers are cancelled

Added runLogoCommands() tests

• evalOnStartList plugin execution
• Listener cleanup
• Drum block handling in startBlocks

Added runFromBlockNow() tests

• MAX_ITERATIONS guard
• evalFlowDict plugin dispatch
• Null-value argument block handling

Added constructor compatibility tests

• Activity facade delegation
• Empty collection initialization
• Initial state verification

Added miscellaneous edge-case tests

• Empty stepQueue
• Multiple turtle initialization
• clearNoteParams() state reset

Coverage Improvement (logo.js)

Metric	Before	After
Statements	82.53%	87.66%
Branches	68.66%	72.18%
Functions	72.13%	80.32%
Lines	82.93%	88.10%

Testing Performed

• Ran npx jest js/tests/logo.test.js
• Ran the full Jest test suite to ensure no regressions
• Verified ESLint and Prettier pass

Checklist

• Tests added for new and existing behavior
• No production code changes
• Full test suite passes
• ESLint and Prettier pass
• Existing functionality remains unchanged
• Tests

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 56.70%. Comparing base (a138477) to head (18d057c).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7746      +/-   ##
==========================================
+ Coverage   56.60%   56.70%   +0.09%     
==========================================
  Files         172      172              
  Lines       57675    57675              
==========================================
+ Hits        32645    32702      +57     
+ Misses      25030    24973      -57     

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[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.

[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.

[vanshika2720]

@walterbender

[walterbender]

Wow. A big improvement. Thx.