tests/service/costandusagereporting: Migrate to automatic region lookup

Reference: #8316
Reference: #15737

Output from acceptance testing in AWS Commercial:

```
--- PASS: TestAccAwsCurReportDefinition_refresh (13.35s)
--- PASS: TestAccAwsCurReportDefinition_overwrite (13.53s)
--- PASS: TestAccAwsCurReportDefinition_athena (13.55s)
--- PASS: TestAccAwsCurReportDefinition_basic (13.56s)
--- PASS: TestAccAwsCurReportDefinition_textOrCsv (13.77s)
--- PASS: TestAccAwsCurReportDefinition_parquet (13.83s)

--- PASS: TestAccDataSourceAwsCurReportDefinition_additional (15.71s)
--- PASS: TestAccDataSourceAwsCurReportDefinition_basic (16.05s)
```

Output from acceptance testing in AWS GovCloud (US):

```
--- SKIP: TestAccAwsCurReportDefinition_refresh (1.22s)
--- SKIP: TestAccAwsCurReportDefinition_athena (1.22s)
--- SKIP: TestAccAwsCurReportDefinition_basic (1.23s)
--- SKIP: TestAccAwsCurReportDefinition_textOrCsv (1.23s)
--- SKIP: TestAccAwsCurReportDefinition_overwrite (1.24s)
--- SKIP: TestAccAwsCurReportDefinition_parquet (1.25s)
```

aws/cur_test.go

@@ -0,0 +1,83 @@
+package aws
+
+import (
+	"context"
+	"sync"
+	"testing"
+
+	"github.com/aws/aws-sdk-go/aws/endpoints"
+	"github.com/aws/aws-sdk-go/service/costandusagereportservice"
+	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
+	"github.com/hashicorp/terraform-plugin-sdk/v2/terraform"
+)
+
+// testAccCurRegion is the chosen Cost and Usage Reporting testing region
+//
+// Cached to prevent issues should multiple regions become available.
+var testAccCurRegion string
+
+// testAccProviderCur is the Cost and Usage Reporting provider instance
+//
+// This Provider can be used in testing code for API calls without requiring
+// the use of saving and referencing specific ProviderFactories instances.
+//
+// testAccPreCheckCur(t) must be called before using this provider instance.
+var testAccProviderCur *schema.Provider
+
+// testAccProviderCurConfigure ensures the provider is only configured once
+var testAccProviderCurConfigure sync.Once
+
+// testAccPreCheckCur verifies AWS credentials and that Cost and Usage Reporting is supported
+func testAccPreCheckCur(t *testing.T) {
+	testAccPartitionHasServicePreCheck(costandusagereportservice.ServiceName, t)
+
+	// Since we are outside the scope of the Terraform configuration we must
+	// call Configure() to properly initialize the provider configuration.
+	testAccProviderCurConfigure.Do(func() {
+		testAccProviderCur = Provider()
+
+		config := map[string]interface{}{
+			"region": testAccGetCurRegion(),
+		}
+
+		err := testAccProviderCur.Configure(context.Background(), terraform.NewResourceConfigRaw(config))
+
+		if err != nil {
+			t.Fatal(err)
+		}
+	})
+}
+
+// testAccCurRegionProviderConfig is the Terraform provider configuration for Cost and Usage Reporting region testing
+//
+// Testing Cost and Usage Reporting assumes no other provider configurations
+// are necessary and overwrites the "aws" provider configuration.
+func testAccCurRegionProviderConfig() string {
+	return testAccRegionalProviderConfig(testAccGetCurRegion())
+}
+
+// testAccGetCurRegion returns the Cost and Usage Reporting region for testing
+func testAccGetCurRegion() string {
+	if testAccCurRegion != "" {
+		return testAccCurRegion
+	}
+
+	if rs, ok := endpoints.RegionsForService(endpoints.DefaultPartitions(), testAccGetPartition(), costandusagereportservice.ServiceName); ok {
+		// return available region (random if multiple)
+		for regionID := range rs {
+			testAccCurRegion = regionID
+			return testAccCurRegion
+		}
+	}
+
+	testAccCurRegion = testAccGetRegion()
+
+	return testAccCurRegion
+}
+
+// testAccProviderFactoriesCur initializes providers for Cost and Usage Reporting testing.
+//
+// Deprecated: This will be replaced with testAccProviderFactories when it only returns the "aws" provider
+func testAccProviderFactoriesCur() map[string]func() (*schema.Provider, error) {
+	return testAccProviderFactoriesInit(nil, []string{ProviderNameAws})
+}

aws/data_source_aws_cur_report_definition_test.go

@@ -2,7 +2,6 @@ package aws
 
 import (
 	"fmt"
-	"os"
 	"testing"
 
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/acctest"
@@ -11,22 +10,16 @@ import (
 )
 
 func TestAccDataSourceAwsCurReportDefinition_basic(t *testing.T) {
-	testAccPartitionHasServicePreCheck("cur", t) // This check must come before os.Setenv() or creds fail on GovCloud
-
-	oldvar := os.Getenv("AWS_DEFAULT_REGION")
-	os.Setenv("AWS_DEFAULT_REGION", "us-east-1") // lintignore:AWSAT003
-	defer os.Setenv("AWS_DEFAULT_REGION", oldvar)
-
 	resourceName := "aws_cur_report_definition.test"
 	datasourceName := "data.aws_cur_report_definition.test"
 
 	reportName := acctest.RandomWithPrefix("tf_acc_test")
 	bucketName := fmt.Sprintf("tf-test-bucket-%d", acctest.RandInt())
 
 	resource.ParallelTest(t, resource.TestCase{
-		PreCheck:     func() { testAccPreCheck(t); testAccPreCheckAWSCur(t) },
-		Providers:    testAccProviders,
-		CheckDestroy: testAccCheckAwsCurReportDefinitionDestroy,
+		PreCheck:          func() { testAccPreCheck(t); testAccPreCheckCur(t) },
+		ProviderFactories: testAccProviderFactoriesCur(),
+		CheckDestroy:      testAccCheckAwsCurReportDefinitionDestroy,
 		Steps: []resource.TestStep{
 			{
 				Config: testAccDataSourceAwsCurReportDefinitionConfig_basic(reportName, bucketName),
@@ -47,22 +40,16 @@ func TestAccDataSourceAwsCurReportDefinition_basic(t *testing.T) {
 }
 
 func TestAccDataSourceAwsCurReportDefinition_additional(t *testing.T) {
-	testAccPartitionHasServicePreCheck("cur", t) // This check must come before os.Setenv() or creds fail on GovCloud
-
-	oldvar := os.Getenv("AWS_DEFAULT_REGION")
-	os.Setenv("AWS_DEFAULT_REGION", "us-east-1") //lintignore:AWSAT003
-	defer os.Setenv("AWS_DEFAULT_REGION", oldvar)
-
 	resourceName := "aws_cur_report_definition.test"
 	datasourceName := "data.aws_cur_report_definition.test"
 
 	reportName := acctest.RandomWithPrefix("tf_acc_test")
 	bucketName := fmt.Sprintf("tf-test-bucket-%d", acctest.RandInt())
 
 	resource.ParallelTest(t, resource.TestCase{
-		PreCheck:     func() { testAccPreCheck(t); testAccPreCheckAWSCur(t) },
-		Providers:    testAccProviders,
-		CheckDestroy: testAccCheckAwsCurReportDefinitionDestroy,
+		PreCheck:          func() { testAccPreCheck(t); testAccPreCheckCur(t) },
+		ProviderFactories: testAccProviderFactoriesCur(),
+		CheckDestroy:      testAccCheckAwsCurReportDefinitionDestroy,
 		Steps: []resource.TestStep{
 			{
 				Config: testAccDataSourceAwsCurReportDefinitionConfig_additional(reportName, bucketName),
@@ -98,14 +85,10 @@ func testAccDataSourceAwsCurReportDefinitionCheckExists(datasourceName, resource
 	}
 }
 
-// note: cur report definitions are currently only supported in us-east-1
 func testAccDataSourceAwsCurReportDefinitionConfig_basic(reportName string, bucketName string) string {
-	//lintignore:AWSAT003,AWSAT005
-	return fmt.Sprintf(`
-provider "aws" {
-  region = "us-east-1"
-}
-
+	return composeConfig(
+		testAccCurRegionProviderConfig(),
+		fmt.Sprintf(`
 data "aws_billing_service_account" "test" {}
 
 resource "aws_s3_bucket" "test" {
@@ -165,16 +148,13 @@ resource "aws_cur_report_definition" "test" {
 data "aws_cur_report_definition" "test" {
   report_name = aws_cur_report_definition.test.report_name
 }
-`, reportName, bucketName)
+`, reportName, bucketName))
 }
 
 func testAccDataSourceAwsCurReportDefinitionConfig_additional(reportName string, bucketName string) string {
-	//lintignore:AWSAT003,AWSAT005
-	return fmt.Sprintf(`
-provider "aws" {
-  region = "us-east-1"
-}
-
+	return composeConfig(
+		testAccCurRegionProviderConfig(),
+		fmt.Sprintf(`
 data "aws_billing_service_account" "test" {}
 
 resource "aws_s3_bucket" "test" {
@@ -236,5 +216,5 @@ resource "aws_cur_report_definition" "test" {
 data "aws_cur_report_definition" "test" {
   report_name = aws_cur_report_definition.test.report_name
 }
-`, reportName, bucketName)
+`, reportName, bucketName))
 }