Add test coverage infrastructure and comprehensive unit tests for core components#461

Draft

Copilot wants to merge 14 commits intomasterfrom

copilot/improve-unit-tests-coverage

Commits on Jan 7, 2026

Initial plan
Copilot
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Add coverage reporting infrastructure to CI/CD pipeline

Copilot
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lukasmatta
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Add comprehensive tests for button, checkbox, switch, chip, and tag components

Copilot
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lukasmatta
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Add tests for divider, loader, and progress components

Copilot
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lukasmatta
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Configure realistic coverage thresholds for incremental improvement

Copilot
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lukasmatta
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Fix ControlValueAccessor test patterns based on code review feedback

Copilot
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lukasmatta
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Replace unmaintained lcov-reporter-action and remove Codecov integration

Copilot
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lukasmatta
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Fix typos
lukasmatta
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