aws/endpoints: Update unit tests use static data instead of live model (

#4389)

Updates the SDK's endpoints model unit tests to ensure that unit tests
are performed on static data instead of the live model that can be
updated at any time. This change was done to ensure that upstream
sources of endpoint models making semantic changes do not cause unit
tests to break.

aws/endpoints/endpoints_test.go

@@ -5,6 +5,12 @@ package endpoints
 
 import "testing"
 
+// ***************************************************************************
+// All endpoint metadata is sourced from the testdata/endpoints.json file at
+// test startup. Not the live endpoints model file. Update the testdata file
+// for the tests to use the latest live model.
+// ***************************************************************************
+
 func TestEnumDefaultPartitions(t *testing.T) {
 	resolver := DefaultResolver()
 	enum, ok := resolver.(EnumPartitions)

aws/endpoints/example_test.go

@@ -13,6 +13,12 @@ import (
 	"github.com/aws/aws-sdk-go/service/sqs"
 )
 
+// ***************************************************************************
+// All endpoint metadata is sourced from the testdata/endpoints.json file at
+// test startup. Not the live endpoints model file. Update the testdata file
+// for the tests to use the latest live model.
+// ***************************************************************************
+
 func ExampleEnumPartitions() {
 	resolver := endpoints.DefaultResolver()
 	partitions := resolver.(endpoints.EnumPartitions).Partitions()
@@ -31,7 +37,9 @@ func ExampleEnumPartitions() {
 }
 
 func ExampleResolverFunc() {
-	myCustomResolver := func(service, region string, optFns ...func(*endpoints.Options)) (endpoints.ResolvedEndpoint, error) {
+	myCustomResolver := func(service, region string, optFns ...func(*endpoints.Options)) (
+		endpoints.ResolvedEndpoint, error,
+	) {
 		if service == endpoints.S3ServiceID {
 			return endpoints.ResolvedEndpoint{
 				URL:           "s3.custom.endpoint.com",

aws/endpoints/main_test.go

@@ -0,0 +1,49 @@
+package endpoints
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+// Update all endpoints partition variables data to be the static testdata
+// model instead of the dynamic live model. This ensures that endpoint tests
+// are tested against static data, and will not break when the live
+// endpoints.json model is updated.
+
+func TestMain(m *testing.M) {
+	testdataFilename := filepath.Join("testdata", "endpoints.json")
+
+	testdataFile, err := os.Open(testdataFilename)
+	if err != nil {
+		panic(fmt.Sprintf("failed to open test endpoints model, %v", err))
+	}
+
+	resolver, err := DecodeModel(testdataFile)
+	if err != nil {
+		panic(fmt.Sprintf("failed to decode test endpoints model, %v", err))
+	}
+
+	partitions, ok := resolver.(partitions)
+	if !ok {
+		panic(fmt.Sprintf("expect %T resolver, got %T", partitions, resolver))
+	}
+
+	for _, p := range partitions {
+		switch p.ID {
+		case "aws":
+			awsPartition = p
+		case "aws-cn":
+			awscnPartition = p
+		case "aws-us-gov":
+			awsusgovPartition = p
+		case "aws-iso":
+			awsisoPartition = p
+		case "aws-iso-b":
+			awsisobPartition = p
+		default:
+			panic("unknown endpoints partition " + p.ID)
+		}
+	}
+}