Breaking API Changes Detection

Breaking API changes detection identifies component modifications that will break existing consumer code. Early detection prevents accidental breaking changes from reaching production and enables proper planning when breaking changes are intentional. Detection mechanisms verify that changes maintain backward compatibility.

What Are Breaking API Changes

Breaking API changes are modifications to component interfaces that cause existing consumer code to stop working correctly. Examples include removing props that consumers use, changing prop types in incompatible ways, altering prop behavior that consumers depend on, and renaming exports that consumers import. Breaking changes require consumer code updates.

Breaking changes are distinguished from additive changes. Adding a new optional prop is additive and backward compatible. Removing an existing prop is breaking because consumers using it will fail. Detection systems must identify which changes fall into which category.

How Breaking API Changes Detection Works

Type comparison tools analyze TypeScript definitions between versions. Tools like api-extractor, tsc-diff, or custom comparison scripts identify removed exports, removed or renamed props, changed prop types, and modified function signatures. Type comparison catches structural breaking changes automatically.

Behavioral testing verifies that documented behaviors remain intact. Consumer-facing tests exercise component APIs as consumers would use them. When these tests fail after changes, behavioral breaking changes are indicated. Test suites designed for compatibility verification catch semantic breaking changes that type comparison misses.

Snapshot comparison tracks interface stability. API snapshots capture current interfaces. Changes that modify these snapshots require review. Snapshot comparison catches any interface change, breaking or not, enabling evaluation of each change’s impact.

Consumer simulation tests representative consumer usage patterns. Sample applications or test suites that mimic how consumers use components verify that changes do not break realistic usage. Consumer simulation catches integration-level breaking changes.

CI integration runs detection automatically. Pull requests that modify components trigger breaking change detection. Results inform reviewers about potential impact. Configuration can block merging when breaking changes are detected or require acknowledgment.

Key Considerations

• Detection depends on accurate knowledge of consumer usage patterns
• Some breaking changes only manifest at runtime rather than compile time
• Detection cannot guarantee no breakage; edge cases may escape detection
• Breaking change tolerance varies by component stability commitment
• Intentional breaking changes require different handling than accidental ones

Common Questions

What types of changes are considered breaking?

Several change categories typically constitute breaking changes. Prop removal eliminates props consumers may use. Prop type narrowing removes values that consumers may provide. Required prop addition forces consumers to provide new values. Behavioral changes alter how components respond to inputs consumers depend on. Export renaming or removal breaks import statements. Default value changes alter behavior consumers may expect. CSS selector changes break consumer style overrides. Event payload changes break consumer event handlers. The specific definition depends on organizational API compatibility commitments and what consumers are documented as being able to rely upon.

How should organizations handle intentional breaking changes?

Intentional breaking changes require structured processes. Deprecation warnings alert consumers to upcoming changes before they occur. Version bumps using semantic versioning signal breaking changes through major version increments. Migration guides document how consumers should update their code. Codemods automate mechanical transformations where possible. Communication channels notify consumers about changes and timelines. Transition periods allow time for consumer migration before old patterns stop working. Long-term support for previous versions may be appropriate for widely-used components. These processes manage breaking change impact while enabling necessary evolution.

Summary

Breaking API changes detection identifies modifications that will break consumer code through type comparison, behavioral testing, snapshot comparison, and consumer simulation. Detection integrates into CI pipelines to flag potential breaking changes during review. Breaking change categories include prop removal, type narrowing, required additions, behavioral changes, and export modifications. Intentional breaking changes require deprecation, versioning, migration support, and consumer communication to manage impact while enabling component evolution.