Terraform working directory not set to `ConfigDirectory` when in use

[austinvalle]

terraform-plugin-testing version

github.com/hashicorp/terraform-plugin-testing v1.6.0

The following code was from the local provider when attempting to refactor some of the tests to use ConfigDirectory: https://github.com/hashicorp/terraform-provider-local/blob/3b59b2e8a560c88b572fb46d3965bc9ae3a52ff3/internal/provider/data_source_local_file_test.go

Problem

Implementing a test utilizing (TestStep).ConfigDirectory with the following directory structure:

 $ tree
.
├── data_source_local_file.go
├── data_source_local_file_test.go
├── .... other files
└── testdata
    └── TestLocalFileDataSource
        ├── local_file
        ├── main.tf

data_source_local_file_test.go

func TestLocalFileDataSource(t *testing.T) {
	content := "This is some content"
	checkSums := genFileChecksums([]byte(content))

	resource.UnitTest(t, resource.TestCase{
		ProtoV5ProviderFactories: protoV5ProviderFactories(),
		Steps: []resource.TestStep{
			{
				ConfigDirectory: config.TestNameDirectory(),
				Check: resource.ComposeAggregateTestCheckFunc(
					resource.TestCheckResourceAttr("data.local_file.file", "content", content),
					resource.TestCheckResourceAttr("data.local_file.file", "content_base64", base64.StdEncoding.EncodeToString([]byte(content))),
					resource.TestCheckResourceAttr("data.local_file.file", "content_md5", checkSums.md5Hex),
					resource.TestCheckResourceAttr("data.local_file.file", "content_sha1", checkSums.sha1Hex),
					resource.TestCheckResourceAttr("data.local_file.file", "content_sha256", checkSums.sha256Hex),
					resource.TestCheckResourceAttr("data.local_file.file", "content_base64sha256", checkSums.sha256Base64),
					resource.TestCheckResourceAttr("data.local_file.file", "content_sha512", checkSums.sha512Hex),
					resource.TestCheckResourceAttr("data.local_file.file", "content_base64sha512", checkSums.sha512Base64),
				),
			},
		},
	})
}

When attempting to reference the local_file file from the terraform config directory, you can't use a relative reference, as the working directory is not set to testdata/TestLocalFileDataSource.

main.tf (error)

data "local_file" "file" {
  # This doesn't work, throws an error saying the file can't be found
  filename = "${path.module}/local_file"
}

main.tf (success)

data "local_file" "file" {
  # This works
  filename = "${path.module}/testdata/TestLocalFileDataSource/local_file"
}

Proposal

We should copy the contents of ConfigDirectory to the root of the working directory that terraform will run in. This may have compatibility concerns? Open to other suggestions.

At the very least, we should document that this behavior exists if we opt not to fix it.

[bflad]

Just to provide context on the issue title wording: we intentionally use a temporary working directory to not potentially leave testing-caused files in provider codebase. If I recall, we also wanted ConfigDirectory to copy the running test directory sub-directories (e.g. the top level testdata in your example) similar to how it worked with the prior Config field, so developers could migrate between the two without necessarily changing the Terraform configuration. I think both of these behaviors are desirable in the testing logic over potentially using the ConfigDirectory as the working directory directly.

I do personally think it would be nice if we did copy all files/directories from ConfigDirectory to the temporary working directory to do exactly as you propose though, however, there may be a wrinkle here if there are duplicate directory names between the running test directory sub-directories and ConfigDirectory sub-directories (e.g. if both had their own testdata directories in your example). Maybe pretty uncommon, but the testing logic should probably do something in that situation (e.g. error) rather than picking one or something. Off the top of head, I'm not sure if there are other compatibility concerns if we do wind up copying the ConfigDirectory files/sub-directories.

[bbasata]

A question about recursive ConfigDirectory copy (it's not recursive 😃) led me to take a fresh look at this issue.

I believe the key to the behavior in this issue's original post is provider reattach. I think all of these are true:

• Terraform itself runs in the temporary working directory
• The ConfigDirectory contents are non-recursively copied to the temporary working directory
• The testdata directory is symlinked into the temporary working directory
• When we run go test in the local provider, then the provider server runs in the go test process, and the provider's working directory == the source directory
• ^^^ is different than what the result we'd get when Terraform itself starts the provider as a co-process
• The relative path in this test works because ./testdata/TestLocalFileDataSource/local_file exists relative to the source directory, i.e. the provider's working directory; the testdata symlink in the temporary working directory is not the operative path here
• This behavior does not break relative path handling by Terraform itself (not the provider). For example, I expect that a module block with a relative path will search the temporary working directory.