When implementing or extending functionality, ensure tests (primarily unit tests for non-renderer code) cover the full supported behavior surface—not just a subset. Apply this as: - For new/expanded supported inputs (e.g., HTML tags), add test cases for every supported variant. - Keep unit tests mandatory for all non-renderer code; use integration tests for renderers. Example pattern (unit-test style): ```js const supportedTags = ['em','strong','sup','a','ul','li']; describe('timeline label HTML support', () => { supportedTags.forEach((tag) => { it(`renders timeline label with <${tag}>`, () => { const input = `Label with <${tag}>text`; const output = renderTimelineLabel(input); // your unit-level function expect(output).toContainTag(tag); // adapt to your assertion style }); }); }); ``` This standard prevents partial coverage (only testing `
`/``) and ensures consistent test expectations across the codebase.