test-coverage

A remediation workflow for raising and enforcing the 80% line-coverage hard gate that Cognite Flows apps must pass before approval. Rather than only reporting where coverage is thin, the skill actively closes gaps: it configures the test tooling, writes the missing tests, exercises untested code paths, and refactors code for testability when needed. It is meant to be run against a single file or directory passed as an argument, or against the whole app when no argument is supplied.

The work proceeds through ordered steps. First it verifies that a test framework (Vitest or Jest) is installed and that a coverage section exists in the config, installing @vitest/coverage-v8 and adding a v8 coverage block with text and lcov reporters if they are missing. It then validates coverage scope, insisting that all .ts and .tsx files under src/ count toward the threshold and that only test files, type declarations like vite-env.d.ts, and the main.tsx entry point are excluded; exclusions hiding pages, components, or hooks are stripped out. Next it runs the coverage command, records statements, branches, functions, and lines, and fixes any failing tests caused by missing imports, broken mocks, stale snapshots, missing dependencies, or config errors.

Finally it locates production files that lack a corresponding test and writes comprehensive tests for services, hooks, utils, and contexts, while marking pure presentational components, barrel exports, and type-only files as not requiring tests. It applies framework-appropriate patterns, for example renderHook with QueryClientProvider wrappers for hooks and direct function calls for services and utils, covering happy path, error path, empty state, and edge cases. Use it whenever a Flows app is below the coverage gate or when tests need to be added, fixed, or made to pass. It assumes a pnpm-based React/TypeScript project structure.