Custom State Checks

The package statecheck also provides the StateCheck interface, which can be implemented for a custom state check.

The statecheck.CheckStateRequest contains the current state file, parsed by the terraform-json package.

Here is an example implementation of a state check that asserts that a specific resource attribute has a known type and value:

package example_test

import (
    "context"
    "fmt"

    tfjson "github.com/hashicorp/terraform-json"

    "github.com/hashicorp/terraform-plugin-testing/knownvalue"
    "github.com/hashicorp/terraform-plugin-testing/statecheck"
    "github.com/hashicorp/terraform-plugin-testing/tfjsonpath"
)

var _ statecheck.StateCheck = expectKnownValue{}

type expectKnownValue struct {
    resourceAddress string
    attributePath   tfjsonpath.Path
    knownValue      knownvalue.Check
}

func (e expectKnownValue) CheckState(ctx context.Context, req statecheck.CheckStateRequest, resp *statecheck.CheckStateResponse) {
    var resource *tfjson.StateResource

    if req.State == nil {
        resp.Error = fmt.Errorf("state is nil")
    }

    if req.State.Values == nil {
        resp.Error = fmt.Errorf("state does not contain any state values")
    }

    if req.State.Values.RootModule == nil {
        resp.Error = fmt.Errorf("state does not contain a root module")
    }

    for _, r := range req.State.Values.RootModule.Resources {
        if e.resourceAddress == r.Address {
            resource = r

            break
        }
    }

    if resource == nil {
        resp.Error = fmt.Errorf("%s - Resource not found in state", e.resourceAddress)

        return
    }

    result, err := tfjsonpath.Traverse(resource.AttributeValues, e.attributePath)

    if err != nil {
        resp.Error = err

        return
    }

    if err := e.knownValue.CheckValue(result); err != nil {
        resp.Error = err
    }
}

func ExpectKnownValue(resourceAddress string, attributePath tfjsonpath.Path, knownValue knownvalue.Check) statecheck.StateCheck {
    return expectKnownValue{
        resourceAddress: resourceAddress,
        attributePath:   attributePath,
        knownValue:      knownValue,
    }
}

And example usage:

package example_test

import (
    "testing"

    "github.com/hashicorp/terraform-plugin-testing/helper/resource"
    "github.com/hashicorp/terraform-plugin-testing/knownvalue"
    "github.com/hashicorp/terraform-plugin-testing/statecheck"
    "github.com/hashicorp/terraform-plugin-testing/tfjsonpath"
)

func TestExpectKnownValue_CheckState_Bool(t *testing.T) {
    t.Parallel()

    resource.Test(t, resource.TestCase{
        // Provider definition omitted.
        Steps: []resource.TestStep{
            {
                // Example resource containing a computed boolean attribute named "computed_attribute"
                Config: `resource "test_resource" "one" {}`,
                ConfigStateChecks: []statecheck.StateCheck{
                    statecheck.ExpectKnownValue(
                        "test_resource.one",
                        tfjsonpath.New("computed_attribute"),
                        knownvalue.Bool(true),
                    ),
                },
            },
        },
    })
}