Acceptance Testing Returning JSON Plan Difference After Apply (regression between v2.0.3 and HEAD)

[bflad]

SDK version

Current HEAD (post v2.0.3, pre v2.0.4):

github.com/hashicorp/terraform-plugin-sdk/v2@951f045a9f1406210062af4371b9a7be6e158edb

Relevant provider source code

Can provide if needed.

Terraform Configuration Files

Can provide if needed.

Debug Output

Can provide if needed.

Expected Behavior

v2.0.1 showed the human readable plan difference on refresh after apply issues:

=== CONT  TestAccAWSDmsReplicationTask_basic
TestAccAWSDmsReplicationTask_basic: resource_aws_dms_replication_task_test.go:18: After applying this test step, the plan was not empty.
stdout:
An execution plan has been generated and is shown below.
Resource actions are indicated with the following symbols:
~ update in-place
Terraform will perform the following actions:
# aws_dms_replication_task.dms_replication_task will be updated in-place
~ resource "aws_dms_replication_task" "dms_replication_task" {
id                        = "tf-test-dms-replication-task-e2hd26cy"
migration_type            = "full-load"
replication_instance_arn  = "arn:aws:dms:us-west-2:*******:rep:IJ7XT3Q6SEKNGQV7JC7PDGBQGFJIWMFJHISA4KY"
replication_task_arn      = "arn:aws:dms:us-west-2:*******:task:3P2GAUOSQJUKISSPPWRVOVS6NWW5333VZZTMXLI"
replication_task_id       = "tf-test-dms-replication-task-e2hd26cy"
~ replication_task_settings = jsonencode(
~ {
- BeforeImageSettings               = null -> null

Actual Behavior

=== CONT  TestAccAWSDmsReplicationTask_basic
TestAccAWSDmsReplicationTask_basic: resource_aws_dms_replication_task_test.go:18: Step 1/3 error: After applying this test step, the plan was not empty.
stdout:
{"format_version":"0.1","terraform_version":"0.12.29","planned_values":{"root_module":{"resources":[{"address":"aws_dms_endpoint.dms_endpoint_source","mode":"managed","type":"aws_dms_endpoint","name":"dms_endpoint_source","provider_name":"aws","schema_version":0,"values":{"certificate_arn":"","database_name":"tf-test-dms-db","elasticsearch_settings":[],"endpoint_arn":"arn:aws:dms:us-west-2:*******:endpoint:JIH35DGCIVAHLVA4L3H7S2QJKNIMW5K2X7LDSAY","endpoint_id":"tf-test-dms-endpoint-source-0qkeppvm","endpoint_type":"source","engine_name":"aurora","extra_connection_attributes":"","id":"tf-test-dms-endpoint-source-0qkeppvm","kafka_settings":[],"kinesis_settings":[],"kms_key_arn":"arn:aws:kms:us-west-2:*******:key/f5709827-76e0-4544-b2ec-9d09d1138bb1","mongodb_settings":[],"password":"tftest","port":3306,"s3_settings":[],"server_name":"tf-test-cluster.cluster-xxxxxxx.us-west-2.rds.amazonaws.com","service_access_role":null,"ssl_mode":"none","tags":null,"username":"tftest"}},{"address":"aws_dms_endpoint.dms_endpoint_target","mode":"managed","type":"aws_dms_endpoint","name":"dms_endpoint_target","provider_name":"aws","schema_version":0,"values":{"certificate_arn":"","database_name":"tf-test-dms-db","elasticsearch_settings":[],"endpoint_arn":"arn:...........

Steps to Reproduce

1. TF_ACC=1 go test -run=TestAccAWSDmsReplicationTask_basic -v

References

#578

https://github.com/hashicorp/terraform-plugin-test/blob/025e2cb31d4123a77fcb60455bca889d31fa4239/working_dir.go#L320-L339

terraform-plugin-sdk/internal/plugintest/working_dir.go

Lines 234 to 253 in 951f045

	// SavedPlanStdout returns a stdout capture of the current saved plan file, if any.
	//
	// If no plan is saved or if the plan file cannot be read, SavedPlanStdout returns
	// an error.
	func (wd *WorkingDir) SavedPlanStdout() (string, error) {
	if !wd.HasSavedPlan() {
	return "", fmt.Errorf("there is no current saved plan")
	}
	var ret bytes.Buffer
	wd.tf.SetStdout(&ret)
	defer wd.tf.SetStdout(ioutil.Discard)
	_, err := wd.tf.ShowPlanFile(context.Background(), wd.planFilename(), tfexec.Reattach(wd.reattachInfo))
	if err != nil {
	return "", err
	}
	return ret.String(), nil
	}

[bflad]

Fix proposal: #605

[ghost]

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