| name | add-component-harness |
| description | Workflow for adding a test harness to an existing @skyux/* component in this Nx monorepo. Use when asked to "add a harness", "write a test harness", "create a SkyXHarness", or backfill harness coverage for a component that already ships without one. Covers locating the component and its public API, mirroring a sibling harness, writing the harness + filters + spec, wiring the testing/src/public-api.ts barrel and documentation.json, and the test/lint/format gate. For brand-new components, use the add-skyux-component skill instead (its step 6 creates the harness). |
| argument-hint | <library> <ComponentName> (e.g. forms SkyCheckbox) |
Add a Test Harness to an Existing Component
Use this skill to backfill or add a CDK component test harness for a component
that already lives in a published @skyux/* library. The detailed conventions
live in
component-harnesses.instructions.md
(it auto-applies to **/libs/components/**/testing/src/modules/**) — read it
before writing code rather than guessing.
Read AGENTS.md first if you are not already familiar with
the monorepo's conventions (Nx tasks, public API discipline, the sky/Sky
export prefix, the Karma vs. Jest split, and Conventional Commits).
When to Use
- A consumer needs a harness for an existing component that doesn't have one.
- Extending an existing harness to cover newly added component inputs/outputs.
Do NOT use this skill to:
- Create a brand-new component — use the
add-skyux-component skill, which creates
the harness as part of its flow.
- Author harnesses outside
libs/components/* (the harness base classes and
documentation.json wiring are specific to those libraries).
Procedure
Work top to bottom. Follow the canonical patterns in
component-harnesses.instructions.md
for all code-level detail; open a sibling harness only to look up facts
(which sub-harness a child component exposes, the template's CSS classes), not
to copy its structure or naming.
-
Locate the component and read its public API. Find the component under
libs/components/<library>/src/lib/modules/<module>/. Note its tag/selector
(the hostSelector), every public input()/@Input(), output(),
model(), the relevant template CSS classes, and any child SKY UX
components (candidates for sub-harness composition). The harness should
expose this surface and nothing internal.
-
Choose a base class (SkyComponentHarness or
SkyQueryableComponentHarness) per the instruction file's
"Choosing a base class".
-
Create the harness, filters, and spec under
libs/components/<library>/testing/src/modules/<module>/
(<component>-harness.ts, <component>-harness-filters.ts, and
<component>-harness.spec.ts) following
component-harnesses.instructions.md
for the class structure, locators, filters, and spec conventions. The
harness must expose the public API surface identified in step 1, and the
spec must cover every public method and thrown-error path (most projects
enforce 100% coverage).
-
Wire the public API. Export the harness and its filters from
libs/components/<library>/testing/src/public-api.ts, using the sky/Sky
prefix.
-
Update documentation. Add both doc IDs to the library's
documentation.json under the matching group's testing.docsIds
(e.g. ["SkyExampleHarness", "SkyExampleHarnessFilters"]).
-
Verify. Run the testing project's specs headless, then lint and format:
npx nx test <library>-testing --browsers=ChromeHeadless
npm run lint:affected
nx format --files=<changed-file-paths>
-
Commit. Use a Conventional Commit with the components/<library> scope
per
commit-message.instructions.md.
Definition of Done
- Harness, filters, and harness spec exist under the library's
testing/
tree and follow the patterns in the instruction file.
- The harness exposes the component's public API (inputs/outputs/models, key
interactions, child harnesses) with JSDoc on the class and every public
member;
hostSelector is @internal.
- Harness and filters are exported (with the
sky/Sky prefix) from
testing/src/public-api.ts and listed in documentation.json's
testing.docsIds.
npx nx test <library>-testing passes at the project's coverage threshold,
lint is clean, and changed files are formatted.
