Example from: https://github.com/gruntwork-io/terratest/blob/62f6d380e87345ebf11c931671cc740d7968adb7/test/helm_basic_example_template_test.go#L36-L80

helm_basic_example_template_test.go

// An example of how to verify the rendered template object of a Helm Chart given various inputs.
func TestHelmBasicExampleTemplateRenderedDeployment(t *testing.T) {
	t.Parallel()

	// Path to the helm chart we will test
	helmChartPath, err := filepath.Abs("../examples/helm-basic-example")
	releaseName := "helm-basic"
	require.NoError(t, err)

	// Since we aren't deploying any resources, there is no need to setup kubectl authentication or helm home.

	// Set up the namespace; confirm that the template renders the expected value for the namespace.
	namespaceName := "medieval-" + strings.ToLower(random.UniqueId())
	logger.Logf(t, "Namespace: %s\n", namespaceName)

	// Setup the args. For this test, we will set the following input values:
	// - containerImageRepo=nginx
	// - containerImageTag=1.15.8
	options := &helm.Options{
		SetValues: map[string]string{
			"containerImageRepo": "nginx",
			"containerImageTag":  "1.15.8",
		},
		KubectlOptions: k8s.NewKubectlOptions("", "", namespaceName),
	}

	// Run RenderTemplate to render the template and capture the output. Note that we use the version without `E`, since
	// we want to assert that the template renders without any errors.
	// Additionally, although we know there is only one yaml file in the template, we deliberately path a templateFiles
	// arg to demonstrate how to select individual templates to render.
	output := helm.RenderTemplate(t, options, helmChartPath, releaseName, []string{"templates/deployment.yaml"})

	// Now we use kubernetes/client-go library to render the template output into the Deployment struct. This will
	// ensure the Deployment resource is rendered correctly.
	var deployment appsv1.Deployment
	helm.UnmarshalK8SYaml(t, output, &deployment)

	// Verify the namespace matches the expected supplied namespace.
	require.Equal(t, namespaceName, deployment.Namespace)

	// Finally, we verify the deployment pod template spec is set to the expected container image value
	expectedContainerImage := "nginx:1.15.8"
	deploymentContainers := deployment.Spec.Template.Spec.Containers
	require.Equal(t, len(deploymentContainers), 1)
	require.Equal(t, deploymentContainers[0].Image, expectedContainerImage)
}