How do I implement terratest(golang) with customized "terraform apply" command?

Question

I use the following lines to run my terraform plan & apply in example/ folder:

"aws-vault exec sandbox-admin-role --region=us-east-2 -- terraform plan -out=tfplan --var-file=customized.us-east-2.tfvars"
"aws-vault exec sandbox-admin-role --region=us-east-2 -- terraform apply --auto-approve tfplan"

They are running fine & I can destroy it with similar command:

aws-vault exec sandbox-admin-role --region=us-east-2 -- terraform destroy --auto-approve --var-file=customized.us-east-2.tfvars

How do I test it in Golang/terratest with customized terraform command like above? This is my golang lines testing the the terraform module.

package test
...
...
func TestTerraformAwsS3Example(t *testing.T) {
    t.Parallel()
...
    terraformOptions := terraform.WithDefaultRetryableErrors(t, &terraform.Options{
        TerraformDir: "../examples",
        VarFiles:     []string{"customized.us-east-2.tfvars"},
    })
    
    defer terraform.Destroy(t, terraformOptions)
    
    terraform.InitAndApply(t, terraformOptions)

And I got the following errors when running "go test -v test/s3-bucket_test.go":

TestTerraformAwsS3Example 2022-03-01T19:14:33-06:00 logger.go:66: Terraform has been successfully initialized!
TestTerraformAwsS3Example 2022-03-01T19:14:33-06:00 logger.go:66: 
TestTerraformAwsS3Example 2022-03-01T19:14:33-06:00 logger.go:66: You may now begin working with Terraform. Try running "terraform plan" to see
TestTerraformAwsS3Example 2022-03-01T19:14:33-06:00 logger.go:66: any changes that are required for your infrastructure. All Terraform commands
TestTerraformAwsS3Example 2022-03-01T19:14:33-06:00 logger.go:66: should now work.
TestTerraformAwsS3Example 2022-03-01T19:14:33-06:00 logger.go:66: 
TestTerraformAwsS3Example 2022-03-01T19:14:33-06:00 logger.go:66: If you ever set or change modules or backend configuration for Terraform,
TestTerraformAwsS3Example 2022-03-01T19:14:33-06:00 logger.go:66: rerun this command to reinitialize your working directory. If you forget, other
TestTerraformAwsS3Example 2022-03-01T19:14:33-06:00 logger.go:66: commands will detect it and remind you to do so if necessary.
TestTerraformAwsS3Example 2022-03-01T19:14:33-06:00 retry.go:91: terraform [apply -input=false -auto-approve -var-file fixtures.us-east-2.tfvars -lock=false]
TestTerraformAwsS3Example 2022-03-01T19:14:33-06:00 logger.go:66: Running command terraform with args [apply -input=false -auto-approve -var-file fixtures.us-east-2.tfvars -lock=false]
TestTerraformAwsS3Example 2022-03-01T19:14:35-06:00 logger.go:66: 
TestTerraformAwsS3Example 2022-03-01T19:14:35-06:00 logger.go:66: Error: Missing required argument
TestTerraformAwsS3Example 2022-03-01T19:14:35-06:00 logger.go:66: 
TestTerraformAwsS3Example 2022-03-01T19:14:35-06:00 logger.go:66: The argument "region" is required, but was not set.
TestTerraformAwsS3Example 2022-03-01T19:14:35-06:00 logger.go:66: 
TestTerraformAwsS3Example 2022-03-01T19:14:35-06:00 retry.go:99: Returning due to fatal error: FatalError{Underlying: error while running command: exit status 1; 
Error: Missing required argument

The argument "region" is required, but was not set.

How do I customize "terraform apply" for the golang test so they could run plan&apply successfully?

Help appreciated!

Answer 1

To get rid of the mysterious "The argument "region" is required, but was not set." error. I run the test as follows, the region error is gone:

% aws-vault exec sandbox-admin-role --region=us-east-2 -- go test -v tests/s3-bucket_test.go

    Warning: parent_profile is deprecated, please use include_profile instead in your AWS config
    === RUN   TestTerraformAwsS3Example
    === PAUSE TestTerraformAwsS3Example
    === CONT  TestTerraformAwsS3Example
    TestTerraformAwsS3Example 2022-03-03T10:10:15-06:00 retry.go:91: terraform [init -upgrade=false]
    TestTerraformAwsS3Example 2022-03-03T10:10:15-06:00 logger.go:66: Running command terraform with args [init -upgrade=false]
    TestTerraformAwsS3Example 2022-03-03T10:10:16-06:00 logger.go:66: Initializing modules...
    TestTerraformAwsS3Example 2022-03-03T10:10:16-06:00 logger.go:66: 
    TestTerraformAwsS3Example 2022-03-03T10:10:16-06:00 logger.go:66: Initializing the backend...
    TestTerraformAwsS3Example 2022-03-03T10:10:17-06:00 logger.go:66: 
    TestTerraformAwsS3Example 2022-03-03T10:10:17-06:00 logger.go:66: Initializing provider plugins...
    TestTerraformAwsS3Example 2022-03-03T10:10:17-06:00 logger.go:66: - Using previously-installed hashicorp/null v3.1.0
    TestTerraformAwsS3Example 2022-03-03T10:10:17-06:00 logger.go:66: - Using previously-installed hashicorp/aws v3.74.3
    TestTerraformAwsS3Example 2022-03-03T10:10:17-06:00 logger.go:66: - Using previously-installed hashicorp/random v3.1.0
    TestTerraformAwsS3Example 2022-03-03T10:10:17-06:00 logger.go:66: - Using previously-installed hashicorp/local v2.1.0
    TestTerraformAwsS3Example 2022-03-03T10:10:18-06:00 logger.go:66: 
    TestTerraformAwsS3Example 2022-03-03T10:10:18-06:00 logger.go:66: Terraform has been successfully initialized!
    TestTerraformAwsS3Example 2022-03-03T10:10:18-06:00 logger.go:66: 

I could not find any documentation to alter the terraform.InitAndApply(t, terraformOptions) behavior.