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k3s/tests/TESTING.md

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# Testing Standards in K3s
Testing in K3s comes in 5 forms:
- [Unit](#unit-tests)
- [Integration](#integration-tests)
- [Smoke](#smoke-tests)
- [Performance](#performance)
- [End-to-End (E2E)](#end-to-end-e2e-tests)
This document will explain *when* each test should be written and *how* each test should be
generated, formatted, and run.
Note: all shell commands given are relative to the root k3s repo directory.
___
## Unit Tests
Unit tests should be written when a component or function of a package needs testing.
Unit tests should be used for "white box" testing.
### Framework
All unit tests in K3s follow a [Table Driven Test](https://github.com/golang/go/wiki/TableDrivenTests) style. Specifically, K3s unit tests are automatically generated using the [gotests](https://github.com/cweill/gotests) tool. This is built into the Go vscode extension, has documented integrations for other popular editors, or can be run via command line. Additionally, a set of custom templates are provided to extend the generated test's functionality. To use these templates, call:
```bash
gotests --template_dir=<PATH_TO_K3S>/contrib/gotests_templates
```
Or in vscode, edit the Go extension setting `Go: Generate Tests Flags`
and add `--template_dir=<PATH_TO_K3S>/contrib/gotests_templates` as an item.
To facilitate unit test creation, see `tests/util/runtime.go` helper functions.
### Format
All unit tests should be placed within the package of the file they test.
All unit test files should be named: `<FILE_UNDER_TEST>_test.go`.
All unit test functions should be named: `Test_Unit<FUNCTION_TO_TEST>` or `Test_Unit<RECEIVER>_<METHOD_TO_TEST>`.
See the [etcd unit test](../pkg/etcd/etcd_test.go) as an example.
### Running
```bash
go test ./pkg/... -run Unit
```
Note: As unit tests call functions directly, they are the primary drivers of K3s's code coverage
metric.
___
## Integration Tests
Integration tests should be used to test a specific functionality of k3s that exists across multiple Go packages, either via exported function calls, or more often, CLI commands.
Integration tests should be used for "black box" testing.
See [integration/README.md](./integration/README.md) for more info.
___
## Smoke Tests
Smoke tests are a collection of tests defined under the [tests](../tests) path at the root of this repository.
The sub-directories therein contain fixtures for running simple clusters to assert correct behavior for "happy path" scenarios. These fixtures are mostly self-contained Vagrantfiles describing single-node installations that are easily spun up with Vagrant for the `libvirt` and `virtualbox` providers:
- [Install Script](../tests/install) :arrow_right: scheduled nightly
- [CentOS 7](../tests/install/centos-7) (stand-in for RHEL 7)
- [Rocky Linux 8](../tests/install/rocky-8) (stand-in for RHEL 8)
- [Fedora](../tests/install/fedora)
- [Leap 15.4](../tests/install/opensuse-leap) (stand-in for SLES)
- [MicroOS](../tests/install/opensuse-microos) (stand-in for SLE-Micro)
- [Ubuntu 20.04](../tests/install/ubuntu-focal) (Focal Fossa)
- [Control Groups](../tests/cgroup) :arrow_right: on any code change
- [mode=unified](../tests/cgroup/unified) (cgroups v2)
- [Fedora 35](../tests/cgroup/unified/fedora-35) (rootfull + rootless)
- [Snapshotter](../tests/snapshotter/btrfs/opensuse-leap) :arrow_right: on any code change
- [BTRFS](../tests/snapshotter/btrfs) ([containerd built-in](https://github.com/containerd/containerd/tree/main/snapshots/btrfs))
- [Leap 15.4](../tests/snapshotter/btrfs/opensuse-leap)
When adding new installer test(s) please copy the prevalent style for the `Vagrantfile`.
Ideally, the boxes used for additional assertions will support the default `virtualbox` provider which
enables them to be used by our Github Actions Workflow(s). See:
- [cgroup.yaml](../.github/workflows/cgroup.yaml).
- [install.yaml](../.github/workflows/install.yaml).
### Framework
If you are new to Vagrant, Hashicorp has written some pretty decent introductory tutorials and docs, see:
- https://learn.hashicorp.com/collections/vagrant/getting-started
- https://www.vagrantup.com/docs/installation
#### Plugins and Providers
The `libvirt` and `vmware_desktop` providers cannot be used without first [installing the relevant plugins](https://www.vagrantup.com/docs/cli/plugin#plugin-install)
which are [`vagrant-libvirt`](https://github.com/vagrant-libvirt/vagrant-libvirt) and
[`vagrant-vmware-desktop`](https://www.vagrantup.com/docs/providers/vmware/installation), respectively.
Much like the default [`virtualbox` provider](https://www.vagrantup.com/docs/providers/virtualbox) these will do
nothing useful without also installing the relevant server runtimes and/or client programs.
#### Environment Variables
These can be set on the CLI or exported before invoking Vagrant:
- `TEST_VM_CPUS` (default :arrow_right: 2)<br/>
The number of vCPU for the guest to use.
- `TEST_VM_MEMORY` (default :arrow_right: 2048)<br/>
The number of megabytes of memory for the guest to use.
- `TEST_VM_BOOT_TIMEOUT` (default :arrow_right: 600)<br/>
The time in seconds that Vagrant will wait for the machine to boot and be accessible.
### Running
The **Install Script** tests can be run by changing to the fixture directory and invoking `vagrant up`, e.g.:
```shell
cd tests/install/rocky-8
vagrant up
# the following provisioners are optional. the do not run by default but are invoked
# explicitly by github actions workflow to avoid certain timeout issues on slow runners
vagrant provision --provision-with=k3s-wait-for-node
vagrant provision --provision-with=k3s-wait-for-coredns
vagrant provision --provision-with=k3s-wait-for-local-storage
vagrant provision --provision-with=k3s-wait-for-metrics-server
vagrant provision --provision-with=k3s-wait-for-traefik
vagrant provision --provision-with=k3s-status
vagrant provision --provision-with=k3s-procps
```
The **Control Groups** and **Snapshotter** tests require that k3s binary is built at `dist/artifacts/k3s`.
They are invoked similarly, i.e. `vagrant up`, but with different sets of named shell provisioners.
Take a look at the individual Vagrantfiles and/or the Github Actions workflows that harness them to get
an idea of how they can be invoked.
___
## Performance Tests
Performance tests use Terraform to test large scale deployments of K3s clusters.
See [perf/README.md](./perf/README.md) for more info.
___
## End-to-End (E2E) Tests
E2E tests cover multi-node K3s configuration and administration: bringup, update, teardown etc. across a wide range of operating systems. E2E tests are run nightly as part of K3s quality assurance (QA).
See [e2e/README.md](./e2e/README.md) for more info.
___
## Contributing New Or Updated Tests
We gladly accept new and updated tests of all types. If you wish to create
a new test or update an existing test, please submit a PR with a title that includes the words `<NAME_OF_TEST> (Created/Updated)`.