Test the migration

Before migration, ensure that your SDKv2 provider has adequete test coverage, and that all of your tests pass. During migration, write migration tests to verify that the behaviour of your provider has not been altered by the migration itself. You must also update your existing tests to use a provider factory to test both the SDKv2 and framework versions of your provider.

Background

To reduce the risk of introducing breaking changes during migration, we strongly recommend that your ensure adequate test coverage before you begin migrating your provider to the framework and that all of your tests pass.

During migration, we recommend writing tests to verify that switching from SDKv2 to the framework does not affect your provider's behavior. These tests use identical configuration for both the SDK and the framework, and validate that migrating does not result in Terraform plan changes when there are no configuration changes.

To run your provider's existing tests against your framework implementation, you must update your provider factories to use the framework.

Refer to the Plugin Testing documentation for more details about testing providers that use the framework.

Migration tests

Before you migrate a resource or data source, create a migration test to ensure that the behavior of the resource or data source does not change between the SDKv2 implementation and the framework version.

Each migration test runs terraform plan to generate state with the SDKv2 version of your provider. Next, it generates a plan with the framework version of the provider. This step also verifies that the there are no differences between the plans created by the SDKv2 and provider versions, and confirms that migrating to the framework will not alter the behavior of existing configurations that use your provider.

Use the ExternalProviders field within a resource.TestStep to specify which provider to use during each test step. Specify a version of the provider built on SDKv2 during the first test step, and then use a version of the provider built on the framework in subsequent test steps to verify that Terraform CLI does not detect any planned changes.

External providers

To test migration of a resource or data source to the framework, use an external provider to generate state with a previous version of the provider and then verify that there are no planned changes after migrating to the framework.

Example

This example test uses an external provider to test that the resource's attribute values are the same between the SDK and framework implementations.

func TestResource_UpgradeFromVersion(t *testing.T) {
    /* ... */
    resource.Test(t, resource.TestCase{
        Steps: []resource.TestStep{
            {
                ExternalProviders: map[string]resource.ExternalProvider{
                    "<provider>": {
                        VersionConstraint: "<sdk_version>",
                        Source:            "hashicorp/<provider>",
                    },
                },
                Config: `resource "provider_resource" "example" {
                            /* ... */
                        }`,
                Check: resource.ComposeTestCheckFunc(
                    resource.TestCheckResourceAttr("provider_resource.example", "<attribute>", "<value>"),
                    /* ... */
                ),
            },
            {
                ProtoV6ProviderFactories: protoV6ProviderFactories(),
                Config: `resource "provider_resource" "example" {
                            /* ... */
                        }`,
                // ConfigPlanChecks is a terraform-plugin-testing feature.
                // If acceptance testing is still using terraform-plugin-sdk/v2,
                // use `PlanOnly: true` instead. When migrating to
                // terraform-plugin-testing, switch to `ConfigPlanChecks` or you
                // will likely experience test failures.
                ConfigPlanChecks: resource.ConfigPlanChecks{
                    PreApply: []plancheck.PlanCheck{
                        plancheck.ExpectEmptyPlan(),
                    },
                },
            },
        },
    })
}

• The first TestStep uses ExternalProviders to cause terraform apply to execute with a previous version of the provider, which is built on SDKv2.

• The second TestStep uses ProtoV6ProviderFactories so that the test uses the provider code contained within the provider repository. Then it uses ConfigPlanChecks to verify that an empty (no-op) plan is generated, indicating that configuring using the SDKv2 version of your provider will continue to work the same way after you migrate your provider to the framework.

Testing data sources

Terraform refreshes data sources during every plan operation, but it does not use prior state during the operation. As a result, you should use a separate managed resource or output value to ensure that there are no differences between a data source implemented with SDKv2 and the same data source after migration to the framework.

If you are using Terraform 1.4 and later, use the terraform_data managed resource, which is implicitly available for configurations in Terraform 1.4 and later.

If testing on older versions of Terraform is required, use the null_resource managed resource with an associated ExternalProviders step configuration instead.

Terraform data resource example

In this example, all data source attribute values are compared between the SDKv2 and framework implementations using a terraform_data resource to mirror the attributes from the data source:

func TestDataSource_UpgradeFromVersion(t *testing.T) {
    /* ... */
    resource.Test(t, resource.TestCase{
        Steps: []resource.TestStep{
            {
                ExternalProviders: map[string]resource.ExternalProvider{
                    "<provider>": {
                        VersionConstraint: "<sdk_version>",
                        Source:            "hashicorp/<provider>",
                    },
                },
                Config: `data "provider_datasource" "test" {
                            /* ... */
                        }
                        
                        resource "terraform_data" "test" {
                            input = data.provider_datasource.test
                        }`,
            },
            {
                ProtoV6ProviderFactories: protoV6ProviderFactories(),
                Config: `data "provider_datasource" "test" {
                            /* ... */
                        }
                        
                        resource "terraform_data" "test" {
                            input = data.provider_datasource.test
                        }`,
                // ConfigPlanChecks is a terraform-plugin-testing feature.
                // If acceptance testing is still using terraform-plugin-sdk/v2,
                // use `PlanOnly: true` instead. When migrating to
                // terraform-plugin-testing, switch to `ConfigPlanChecks` or you
                // will likely experience test failures.
                ConfigPlanChecks: resource.ConfigPlanChecks{
                    PreApply: []plancheck.PlanCheck{
                        plancheck.ExpectEmptyPlan(),
                    },
                },
            },
        },
    })
}

Provider factories

In many cases, existing tests do not require significant updates. The only necessary change is to the provider factories that create the provider during the test case. Refer to Acceptance Tests - Specify Providers in the framework documentation for details about selecting specefic provider versions in your tests.

In SDKv2, you use the ProviderFactories field on the resource.TestCase struct to obtain schema.Provider.

The following example shows a test written in SDKv2.

resource.UnitTest(t, resource.TestCase{
    ProviderFactories: testProviders(),

In the framework, use either the ProtoV5ProviderFactories or ProtoV6ProviderFactories field on the resource.TestCase struct to obtain the provider.Provider, depending on the Terraform Plugin Protocol version your provider is using.

Protocol version 6

The following example shows how you can write a test in the framework for a provider that uses protocol version 6.

resource.UnitTest(t, resource.TestCase{
    ProtoV6ProviderFactories: protoV6ProviderFactories(),

Protocol version 5

The following example shows how you can write a test in the framework for a provider that uses protocol version 5.

resource.UnitTest(t, resource.TestCase{
    ProtoV5ProviderFactories: protoV5ProviderFactories(),

Provider factory example

The following code sample shows how to define provider factories within a test case when using SDKv2.

func TestDataSource_Exmple(t *testing.T) {
    /* ... */
    resource.UnitTest(t, resource.TestCase{
        ProviderFactories: testProviders(),
        /* ... */
    })
}

The following shows how to generate provider factories when using SDKv2.

func testProviders() map[string]func() (*schema.Provider, error) {
    return map[string]func() (*schema.Provider, error){
        "example": func() (*schema.Provider, error) { return New(), nil },
    }
}

The following shows how to define provider factories within a test case when using the framework.

func TestDataSource_Example(t *testing.T) {
    /* ... */

    resource.UnitTest(t, resource.TestCase{
        ProtoV6ProviderFactories: protoV6ProviderFactories(),
        /* ... */
    })
}

The following shows how to generate provider factories when using the framework. The call to New returns an instance of the provider. Refer to Provider Definition in this guide for details.

func protoV5ProviderFactories() map[string]func() (tfprotov5.ProviderServer, error) {
    return map[string]func() (tfprotov5.ProviderServer, error){
        "example": providerserver.NewProtocol5WithError(New()),
    }
}