You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: middleware_test.go
    path of file: ./repos/aws-sdk-go-v2/service/internal/presigned-url
    
    the code of the file until where you have to start completion: package presignedurl

import (
	"context"
	
    
func TestPresignMiddleware(t *testing.T) {
	cases := map[string]struct {
		Input *mockURLPresignInput

		ExpectInput *mockURLPresignInput
		ExpectErr   string
	}{
		"no source": {
			Input:       &mockURLPresignInput{},
			ExpectInput: &mockURLPresignInput{},
		},
		"with presigned URL": {
			Input: &mockURLPresignInput{
				SourceRegion: "source-region",
				PresignedURL: "https://example.amazonaws.com/someURL",
			},
			ExpectInput: &mockURLPresignInput{
				SourceRegion: "source-region",
				PresignedURL: "https://example.amazonaws.com/someURL",
			},
		},
		"with source": {
			Input: &mockURLPresignInput{
				SourceRegion: "source-region",
			},
			ExpectInput: &mockURLPresignInput{
				SourceRegion: "source-region",
				PresignedURL: "https://example.source-region.amazonaws.com/?DestinationRegion=mock-region",
			},
		},
		"matching source destination region": {
			Input: &mockURLPresignInput{
				SourceRegion: "mock-region",
			},
			ExpectInput: &mockURLPresignInput{
				SourceRegion: "mock-region",
				PresignedURL: "https://example.mock-region.amazonaws.com/?DestinationRegion=mock-region",
			},
		},
	}

	for name, c := range cases {
		t.Run(name, func(t *testing.T) {
			stack := middleware.NewStack(name, smithyhttp.NewStackRequest)

			stack.Initialize.Add(&awsmiddleware.RegisterServiceMetadata{
				Region: "mock-region",
			}, middleware.After)

			stack.Initialize.Add(&presign{options: getURLPresignMiddlewareOptions()}, middleware.After)

			stack.Initialize.Add(middleware.InitializeMiddlewareFunc(name+"_verifyParams",
				func(ctx context.Context, in middleware.InitializeInput, next middleware.InitializeHandler) (
					out middleware.InitializeOutput, metadata middleware.Metadata, err error,
				) {
					input := in.Parameters.(*mockURLPresignInput)
					if diff := cmpDiff(c.ExpectInput, input); len(diff) != 0 {
						t.Errorf("expect input to be updated\n%s", diff)
					}

					return next.HandleInitialize(ctx, in)
				},
			), middleware.After)

			handler := middleware.DecorateHandler(smithyhttp.NewClientHandler(smithyhttp.NopClient{}), stack)
			_, _, err := handler.Handle(context.Background(), c.Input)
			if len(c.ExpectErr) != 0 {
				if err == nil {
					t.Fatalf("expect error, got none")
				}
				if e, a := c.ExpectErr, err.Error(); !strings.Contains(a, e) {
					t.Fatalf("expect error to contain %v, got %v", e, a)
				}
				return
			}
			if err != nil {
				t.Fatalf("expect no error, got %v", err)
			}
		})
	}
}