TestStep.ImportBlock: testing for import blocks

[kmoe]

Add a new sub-mode of TestStep.ImportState for testing with the new Terraform v1.5 import block feature. The aim of this PR is to allow provider developers to add tests for import blocks with as little work as possible.

The test framework can generate an import block from the parameters already required for an ImportState test, e.g.

import {
  to = test_resource.foo
  id = "123"
}

Provider developers can optionally write their own import block and supply it with TestStep.ImportBlockConfig.

Other functionality for finding the import ID and verifying the import state is shared with existing ImportState testing.

Example usage

An existing ImportState TestStep can be converted into import block tests with the addition of ImportBlock: true, e.g.

		Steps: []resource.TestStep{
			{
				Config: `resource "test_resource" "foo" {}`,
			},
			{
				ResourceName:      resourceName,
				ImportState:       true,
				ImportBlock:       true,
				ImportStateVerify: true,
			},
		},

Design questions

1. Should ImportBlock be a separate TestStep mode entirely, with new TestStep.ImportBlock* fields?

To do

• Deduplicate code between modes
• Handle TestStep.ImportResourceGenerateConfig (for testing terraform plan -generate-config-out)
• Docs (where do these live?)

[bflad]

Hi @kmoe 👋 Thank you for submitting this. Is there any urgency to this feature? We have some design inflection points coming up this quarter to get away from forever growing TestStep type, so it might be best suited to discuss this feature within that context.