How-to test a Charm

1. Write the test cases

Create a <charm name>_test.go file in the same directory as your charm code. This file will contain the test cases for your charm using the goopstest package. Here we assume the charm name is example:

package charm_test

import (
    "example/internal/charm"
    "testing"

    "github.com/gruyaume/goops/goopstest"
)

func TestConfigure(t *testing.T) {
    ctx := goopstest.NewContext(charm.Configure)

    stateIn := goopstest.State{
        Leader: true,
        Config: map[string]any{
            "username": "",
        },
    }

    stateOut := ctx.Run("install", stateIn)

    if ctx.CharmErr != nil {
        t.Fatalf("Configure failed: %v", ctx.CharmErr)
    }

    expectedStatus := goopstest.Status{
        Name:    goopstest.StatusBlocked,
        Message: "Username is not set in config",
    }
    if stateOut.UnitStatus != expectedStatus {
        t.Errorf("expected unit status %v, got %v", expectedStatus, stateOut.UnitStatus)
    }
}

Info

Learn more about goopstest:

• Unit testing explanation
• goopstest API

2. Run the tests

Run the tests using go test ./... -v:

(venv) guillaume@courge:~/example$ go test ./... -v
?       example/cmd/example     [no test files]
=== RUN   TestConfigure
--- PASS: TestConfigure (0.00s)
PASS
ok      example/internal/charm  0.002s