# Testing Charts — Helm

Source: https://www.skillbyai.com/en/helm/q-testing

> Check charts with linting, schema validation, unit tests and install tests.

## Layers of chart testing

Test charts the way you test code, from cheap to expensive. **`helm lint`** catches structural problems and template errors. **Rendering plus Kubernetes schema validation**, for example `helm template ... | kubeconform -strict`, catches misspelled fields and wrong API versions without a cluster. **Unit tests** with the community **helm-unittest** plugin assert on rendered output ("when `ingress.enabled` is true, an Ingress with host X exists"), which protects tricky conditionals from regressions. **Install tests** with the **chart-testing** tool (`ct lint` and `ct install`) install changed charts into a throwaway cluster, often **kind**, run `helm test`, and check that upgrades from the previous version work. Run a value matrix: defaults, production-like values and each optional feature switched on.

## The chart testing ladder

Each step catches more problems but costs more time.

![Four steps rising left to right, each step a slightly larger block, with a small check mark above each.](assets/figures/helm/section-6-map.svg) — Figure 6.1 — Lint, schema validation, unit tests and install tests.

## A helm-unittest test file

Lives in `tests/` inside the chart and runs with `helm unittest ./charts/shop-api`.

```yaml
suite: ingress
templates:
  - templates/ingress.yaml
tests:
  - it: is not rendered by default
    asserts:
      - hasDocuments:
          count: 0

  - it: renders one rule per host
    set:
      ingress.enabled: true
      ingress.className: nginx
      ingress.hosts:
        - host: shop.example.com
        - host: api.example.com
    asserts:
      - isKind:
          of: Ingress
      - equal:
          path: spec.rules[1].host
          value: api.example.com
```

## Test the upgrade, not just the install

Many chart bugs only appear when upgrading an existing release: renamed resources, changed selectors, new required values. chart-testing can install the previous version and upgrade to the new one; use that in CI.

**Quiz:** Which approach validates rendered manifests against Kubernetes schemas without a cluster?

- [ ] helm rollback
- [ ] helm status
- [x] helm template piped to kubeconform
- [ ] kubectl get pods

*Answer:* helm template piped to kubeconform. Rendering offline and validating with kubeconform catches invalid fields and API versions early.