Terratest — Automated Testing for Infrastructure Code

What it is

Terratest is a Go library for writing automated tests for infrastructure code. It deploys real infrastructure (Terraform modules, Kubernetes manifests, Docker images, Packer templates), validates that it works correctly, and then tears it down. Unlike linting or static analysis, Terratest tests actual behavior.

Terratest targets infrastructure engineers and DevOps teams who want confidence that their Terraform modules, Helm charts, and Kubernetes configurations actually work before merging to main.

How it saves time or tokens

Terratest catches infrastructure bugs before they reach production. A broken Terraform module discovered in CI costs minutes. The same bug discovered in production costs hours of debugging and potential downtime. By testing real infrastructure in an isolated environment, you verify networking, IAM permissions, and resource configuration end-to-end.

Terratest also provides helper functions for common assertions (HTTP requests, SSH commands, Kubernetes queries) that would take significant boilerplate to write from scratch.

How to use

1. Create a Go test file in your Terraform module directory:

go mod init test
go get github.com/gruntwork-io/terratest/modules/terraform

1. Write a test that deploys and validates infrastructure:

package test

import (
    "testing"
    "github.com/gruntwork-io/terratest/modules/terraform"
    "github.com/stretchr/testify/assert"
)

func TestWebServer(t *testing.T) {
    opts := &terraform.Options{
        TerraformDir: "../modules/web-server",
        Vars: map[string]interface{}{
            "instance_type": "t3.micro",
        },
    }
    defer terraform.Destroy(t, opts)
    terraform.InitAndApply(t, opts)

    url := terraform.Output(t, opts, "url")
    assert.Contains(t, url, "http")
}

1. Run the test:

go test -v -timeout 30m

Example

Testing a Kubernetes deployment with Terratest:

func TestK8sDeployment(t *testing.T) {
    kubeOpts := k8s.NewKubectlOptions("", "", "test-ns")
    k8s.CreateNamespace(t, kubeOpts, "test-ns")
    defer k8s.DeleteNamespace(t, kubeOpts, "test-ns")

    k8s.KubectlApply(t, kubeOpts, "../manifests/deployment.yaml")
    k8s.WaitUntilDeploymentAvailable(t, kubeOpts, "my-app", 30, 10*time.Second)

    service := k8s.GetService(t, kubeOpts, "my-app")
    assert.Equal(t, int32(80), service.Spec.Ports[0].Port)
}

Related on TokRepo

• AI tools for testing -- Automated testing tools and frameworks
• AI tools for DevOps -- Infrastructure automation and testing

Common pitfalls

• Not setting timeouts. Infrastructure provisioning takes minutes, not seconds. Use go test -timeout 30m and set appropriate retry intervals in Terratest helper functions.
• Testing in shared environments. Always use isolated accounts, namespaces, or resource prefixes to prevent test infrastructure from colliding with production or other test runs.
• Forgetting the defer terraform.Destroy() call. Without it, failed tests leave orphaned cloud resources that accumulate costs.