Helm unit test used in Apache Airflow

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helm unittest

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Unit test for helm chart in YAML to keep your chart consistent and robust!



If you are ready for writing tests, check the DOCUMENT for the test API in YAML.


$ helm plugin install https://github.com/quintush/helm-unittest

It will install the latest version of binary into helm plugin directory.

Get Started

Add tests in .helmignore of your chart, and create the following test file at $YOUR_CHART/tests/deployment_test.yaml:

suite: test deployment
  - deployment.yaml
  - it: should work
      image.tag: latest
      - isKind:
          of: Deployment
      - matchRegex:
          path: metadata.name
          pattern: -my-chart$
      - equal:
          path: spec.template.spec.containers[0].image
          value: nginx:latest

and run:

$ helm unittest $YOUR_CHART

Now there is your first test! ;)

Test Suite File

The test suite file is written in pure YAML, and default placed under the tests/ directory of the chart with suffix _test.yaml. You can also have your own suite files arrangement with -f, --file option of cli set as the glob patterns of test suite files related to chart directory, like:

$ helm unittest -f 'my-tests/*.yaml' -f 'more-tests/*.yaml' my-chart

Check DOCUMENT for more details about writing tests.


$ helm unittest [flags] CHART [...]

This renders your charts locally (without tiller) and runs tests defined in test suite files.


      --color                  enforce printing colored output even stdout is not a tty. Set to false to disable color
  -f, --file stringArray       glob paths of test files location, default to tests\*_test.yaml (default [tests\*_test.yaml])
  -3, --helm3                  parse helm charts as helm3 charts (default false)
  -h, --help                   help for unittest
  -o, --output-file string     output-type the file-format where testresults are written in, accepted types are (JUnit, NUnit, XUnit) (default XUnit)
  -u, --update-snapshot        update the snapshot cached if needed, make sure you review the change before update
  -s, --with-subchart charts   include tests of the subcharts within charts folder (default true)


Check __fixtures__/v2/basic/ for some basic use cases of a simple chart (version < 2). Check __fixtures__/v3/basic/ for some basic use cases of a simple chart (version > 3).

Snapshot Testing

Sometimes you may just want to keep the rendered manifest not changed between changes without every details asserted. That's the reason for snapshot testing! Check the tests below:

  - deployment.yaml
  - it: pod spec should match snapshot
      - matchSnapshot:
          path: spec.template.spec
  # or you can snapshot the whole manifest
  - it: manifest should match snapshot
      - matchSnapshot: {}

The matchSnapshot assertion validate the content rendered the same as cached last time. It fails if the content changed, and you should check and update the cache with -u, --update-snapshot option of cli.

$ helm unittest -u my-chart

The cache files is stored as __snapshot__/v2/*_test.yaml.snap at the directory your test file placed, you should add them in version control with your chart.

Dependend subchart Testing (Requirements.yaml)

If you have dependend subcharts (installed via helm dependency) existed in charts directory (they don't need to be extracted), it is possible to unittest these from the root chart. This feature can be helpfull to validate if good default values are accidently overwritten within your default helm chart.

# $YOUR_CHART/tests/xxx_test.yaml
  - charts/postgresql/templates/xxx.yaml
  - it:
      # this time required to prefix with "postgresql."
      postgresql.somevalue: should_be_scoped
      - ...

Note 1: if dependend subcharts uses an alias, use the alias name in the templates. Note 2: using the folder structure in templates can also be used to unittest templates which are placed in subfolders or unittest subcharts from the rootchart.

Check __fixtures__/v2/with-subchart/ or __fixtures__/v3/with-subchart/ as an example.

Tests within subchart

If you have customized subchart (not installed via helm dependency) existed in charts directory, tests inside would also be executed by default. You can disable this behavior by setting --with-subchart=false flag in cli, thus only the tests in root chart will be executed. Notice that the values defined in subchart tests will be automatically scoped, you don't have to add dependency scope yourself:

# with-subchart/charts/child-chart/tests/xxx_test.yaml
  - xxx.yaml
  - it:
      # no need to prefix with "child-chart."
      somevalue: should_be_scoped
      - ...

Check __fixtures__/v2/with-subchart/ or __fixtures__/v3/with-subchart/ as an example.

Related Projects / Commands

This plugin is inspired by helm-template, and the idea of snapshot testing and some printing format comes from jest.

And there are some other helm commands you might want to use:

  • helm template: render the chart and print the output.

  • helm lint: examines a chart for possible issues, useful to validate chart dependencies.

  • helm test: test a release with testing pod defined in chart. Note this does create resources on your cluster to verify if your release is correct. Check the doc.




Issues and PRs are welcome!
Before start developing this plugin, you must have [go] (https://golang.org/doc/install) >= 1.14 installed, and run:

git clone git@github.com:quintush/helm-unittest.git
cd helm-unittest

And please make CI passed when request a PR which would check following things:

  • gofmt no changes needed. Please run gofmt -w -s . before you commit.
  • go test ./unittest/... passed.

In some cases you might need to manually fix the tests in *_test.go. If the snapshot tests (of the plugin's test code) failed you need to run:

UPDATE_SNAPSHOTS=true go test ./unittest/...

This update the snapshot cache file and please add them before you commit.