tests/resource/aws_lightsail_domain: Remove hardcoded region and standardize disappears testing

Reference: #16302

Output from acceptance testing in AWS Commercial:

```
--- PASS: TestAccAWSLightsailDomain_disappears (10.22s)
--- PASS: TestAccAWSLightsailDomain_basic (10.27s)
```

Output from acceptance testing in AWS GovCloud (US):

```
--- SKIP: TestAccAWSLightsailDomain_basic (1.70s)
--- SKIP: TestAccAWSLightsailDomain_disappears (1.70s)
```

Author: bflad

aws/lightsail_domain_test.go

@@ -0,0 +1,90 @@
+package aws
+
+import (
+	"context"
+	"sync"
+	"testing"
+
+	"github.com/aws/aws-sdk-go/aws/endpoints"
+	"github.com/aws/aws-sdk-go/service/lightsail"
+	"github.com/hashicorp/terraform-plugin-sdk/v2/diag"
+	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
+	"github.com/hashicorp/terraform-plugin-sdk/v2/terraform"
+)
+
+// Lightsail Domains can only be created in specific regions.
+
+// testAccLightsailDomainRegion is the chosen Lightsail Domains testing region
+//
+// Cached to prevent issues should multiple regions become available.
+var testAccLightsailDomainRegion string
+
+// testAccProviderLightsailDomain is the Lightsail Domains provider instance
+//
+// This Provider can be used in testing code for API calls without requiring
+// the use of saving and referencing specific ProviderFactories instances.
+//
+// testAccPreCheckLightsailDomain(t) must be called before using this provider instance.
+var testAccProviderLightsailDomain *schema.Provider
+
+// testAccProviderLightsailDomainConfigure ensures the provider is only configured once
+var testAccProviderLightsailDomainConfigure sync.Once
+
+// Prevent panic with testAccCheckResourceDisappears
+func init() {
+	testAccProviderLightsailDomain = Provider()
+}
+
+// testAccPreCheckLightsailDomain verifies AWS credentials and that Lightsail Domains is supported
+func testAccPreCheckLightsailDomain(t *testing.T) {
+	testAccPartitionHasServicePreCheck(lightsail.EndpointsID, t)
+
+	// Since we are outside the scope of the Terraform configuration we must
+	// call Configure() to properly initialize the provider configuration.
+	testAccProviderLightsailDomainConfigure.Do(func() {
+		region := testAccGetLightsailDomainRegion()
+
+		if region == "" {
+			t.Skip("Lightsail Domains not available in this AWS Partition")
+		}
+
+		config := map[string]interface{}{
+			"region": region,
+		}
+
+		diags := testAccProviderLightsailDomain.Configure(context.Background(), terraform.NewResourceConfigRaw(config))
+
+		if diags != nil && diags.HasError() {
+			for _, d := range diags {
+				if d.Severity == diag.Error {
+					t.Fatalf("error configuring Lightsail Domains provider: %s", d.Summary)
+				}
+			}
+		}
+	})
+}
+
+// testAccLightsailDomainRegionProviderConfig is the Terraform provider configuration for Lightsail Domains region testing
+//
+// Testing Lightsail Domains assumes no other provider configurations
+// are necessary and overwrites the "aws" provider configuration.
+func testAccLightsailDomainRegionProviderConfig() string {
+	return testAccRegionalProviderConfig(testAccGetLightsailDomainRegion())
+}
+
+// testAccGetLightsailDomainRegion returns the Lightsail Domains region for testing
+func testAccGetLightsailDomainRegion() string {
+	if testAccLightsailDomainRegion != "" {
+		return testAccLightsailDomainRegion
+	}
+
+	// AWS Commercial: https://lightsail.aws.amazon.com/ls/docs/en_us/articles/lightsail-how-to-create-dns-entry
+	// AWS GovCloud (US) - service not supported: https://docs.aws.amazon.com/govcloud-us/latest/UserGuide/using-services.html
+	// AWS China - service not supported: https://www.amazonaws.cn/en/about-aws/regional-product-services/
+	switch testAccGetPartition() {
+	case endpoints.AwsPartitionID:
+		testAccLightsailDomainRegion = endpoints.UsEast1RegionID
+	}
+
+	return testAccLightsailDomainRegion
+}

aws/resource_aws_lightsail_domain_test.go

@@ -16,16 +16,17 @@ import (
 func TestAccAWSLightsailDomain_basic(t *testing.T) {
 	var domain lightsail.Domain
 	lightsailDomainName := fmt.Sprintf("tf-test-lightsail-%s.com", acctest.RandString(5))
+	resourceName := "aws_lightsail_domain.test"
 
 	resource.ParallelTest(t, resource.TestCase{
-		PreCheck:     func() { testAccPreCheck(t); testAccPreCheckAWSLightsail(t) },
-		Providers:    testAccProviders,
-		CheckDestroy: testAccCheckAWSLightsailDomainDestroy,
+		PreCheck:          func() { testAccPreCheck(t); testAccPreCheckLightsailDomain(t) },
+		ProviderFactories: testAccProviderFactories,
+		CheckDestroy:      testAccCheckAWSLightsailDomainDestroy,
 		Steps: []resource.TestStep{
 			{
 				Config: testAccAWSLightsailDomainConfig_basic(lightsailDomainName),
 				Check: resource.ComposeAggregateTestCheckFunc(
-					testAccCheckAWSLightsailDomainExists("aws_lightsail_domain.domain_test", &domain),
+					testAccCheckAWSLightsailDomainExists(resourceName, &domain),
 				),
 			},
 		},
@@ -35,30 +36,18 @@ func TestAccAWSLightsailDomain_basic(t *testing.T) {
 func TestAccAWSLightsailDomain_disappears(t *testing.T) {
 	var domain lightsail.Domain
 	lightsailDomainName := fmt.Sprintf("tf-test-lightsail-%s.com", acctest.RandString(5))
-
-	domainDestroy := func(*terraform.State) error {
-		conn := testAccProvider.Meta().(*AWSClient).lightsailconn
-		_, err := conn.DeleteDomain(&lightsail.DeleteDomainInput{
-			DomainName: aws.String(lightsailDomainName),
-		})
-
-		if err != nil {
-			return fmt.Errorf("Error deleting Lightsail Domain in disapear test")
-		}
-
-		return nil
-	}
+	resourceName := "aws_lightsail_domain.test"
 
 	resource.ParallelTest(t, resource.TestCase{
-		PreCheck:     func() { testAccPreCheck(t); testAccPreCheckAWSLightsail(t) },
-		Providers:    testAccProviders,
-		CheckDestroy: testAccCheckAWSLightsailDomainDestroy,
+		PreCheck:          func() { testAccPreCheck(t); testAccPreCheckLightsailDomain(t) },
+		ProviderFactories: testAccProviderFactories,
+		CheckDestroy:      testAccCheckAWSLightsailDomainDestroy,
 		Steps: []resource.TestStep{
 			{
 				Config: testAccAWSLightsailDomainConfig_basic(lightsailDomainName),
 				Check: resource.ComposeAggregateTestCheckFunc(
-					testAccCheckAWSLightsailDomainExists("aws_lightsail_domain.domain_test", &domain),
-					domainDestroy,
+					testAccCheckAWSLightsailDomainExists(resourceName, &domain),
+					testAccCheckResourceDisappears(testAccProviderLightsailDomain, resourceAwsLightsailDomain(), resourceName),
 				),
 				ExpectNonEmptyPlan: true,
 			},
@@ -77,7 +66,7 @@ func testAccCheckAWSLightsailDomainExists(n string, domain *lightsail.Domain) re
 			return errors.New("No Lightsail Domain ID is set")
 		}
 
-		conn := testAccProvider.Meta().(*AWSClient).lightsailconn
+		conn := testAccProviderLightsailDomain.Meta().(*AWSClient).lightsailconn
 
 		resp, err := conn.GetDomain(&lightsail.GetDomainInput{
 			DomainName: aws.String(rs.Primary.ID),
@@ -101,7 +90,7 @@ func testAccCheckAWSLightsailDomainDestroy(s *terraform.State) error {
 			continue
 		}
 
-		conn := testAccProvider.Meta().(*AWSClient).lightsailconn
+		conn := testAccProviderLightsailDomain.Meta().(*AWSClient).lightsailconn
 
 		resp, err := conn.GetDomain(&lightsail.GetDomainInput{
 			DomainName: aws.String(rs.Primary.ID),
@@ -126,13 +115,11 @@ func testAccCheckAWSLightsailDomainDestroy(s *terraform.State) error {
 }
 
 func testAccAWSLightsailDomainConfig_basic(lightsailDomainName string) string {
-	return fmt.Sprintf(`
-provider "aws" {
-  region = "us-east-1"
-}
-
-resource "aws_lightsail_domain" "domain_test" {
+	return composeConfig(
+		testAccLightsailDomainRegionProviderConfig(),
+		fmt.Sprintf(`
+resource "aws_lightsail_domain" "test" {
   domain_name = "%s"
 }
-`, lightsailDomainName) //lintignore:AT004
+`, lightsailDomainName))
 }