Test S3 client via dependency injection

aws/s3.go

@@ -11,6 +11,10 @@ import (
 	"github.com/aws/aws-sdk-go/service/s3/s3manager"
 )
 
+type uploader interface {
+	UploadWithContext(ctx aws.Context, input *s3manager.UploadInput, opts ...func(*s3manager.Uploader)) (*s3manager.UploadOutput, error)
+}
+
 // S3Client is a client for uploading data to S3.
 type S3Client struct {
 	region    string
@@ -18,6 +22,8 @@ type S3Client struct {
 	secretKey string
 	bucket    string
 	key       string
+
+	uploader uploader // for testing via dependency injection
 }
 
 // NewS3Client returns an instance of an S3Client.
@@ -46,7 +52,13 @@ func (s *S3Client) Upload(ctx context.Context, reader io.Reader) error {
 		return fmt.Errorf("failed to create S3 session: %w", err)
 	}
 
-	uploader := s3manager.NewUploader(sess)
+	// If an uploader was not provided, use a real S3 uploader.
+	var uploader uploader
+	if s.uploader == nil {
+		uploader = s3manager.NewUploader(sess)
+	} else {
+		uploader = s.uploader
+	}
 
 	_, err = uploader.UploadWithContext(ctx, &s3manager.UploadInput{
 		Bucket: aws.String(s.bucket),

aws/s3_test.go

@@ -1,29 +1,118 @@
 package aws
 
-import "testing"
+import (
+	"context"
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/aws/aws-sdk-go/aws"
+	"github.com/aws/aws-sdk-go/service/s3/s3manager"
+)
 
 func Test_NewS3Client(t *testing.T) {
 	c := NewS3Client("region1", "access", "secret", "bucket2", "key3")
 	if c.region != "region1" {
-		t.Errorf("expected region to be %q, got %q", "region1", c.region)
+		t.Fatalf("expected region to be %q, got %q", "region1", c.region)
 	}
 	if c.accessKey != "access" {
-		t.Errorf("expected accessKey to be %q, got %q", "access", c.accessKey)
+		t.Fatalf("expected accessKey to be %q, got %q", "access", c.accessKey)
 	}
 	if c.secretKey != "secret" {
-		t.Errorf("expected secretKey to be %q, got %q", "secret", c.secretKey)
+		t.Fatalf("expected secretKey to be %q, got %q", "secret", c.secretKey)
 	}
 	if c.bucket != "bucket2" {
-		t.Errorf("expected bucket to be %q, got %q", "bucket2", c.bucket)
+		t.Fatalf("expected bucket to be %q, got %q", "bucket2", c.bucket)
 	}
 	if c.key != "key3" {
-		t.Errorf("expected key to be %q, got %q", "key3", c.key)
+		t.Fatalf("expected key to be %q, got %q", "key3", c.key)
 	}
 }
 
 func Test_S3Client_String(t *testing.T) {
 	c := NewS3Client("region1", "access", "secret", "bucket2", "key3")
 	if c.String() != "s3://bucket2/key3" {
-		t.Errorf("expected String() to be %q, got %q", "s3://bucket2/key3", c.String())
+		t.Fatalf("expected String() to be %q, got %q", "s3://bucket2/key3", c.String())
+	}
+}
+
+func TestS3ClientUploadOK(t *testing.T) {
+	region := "us-west-2"
+	accessKey := "your-access-key"
+	secretKey := "your-secret-key"
+	bucket := "your-bucket"
+	key := "your/key/path"
+
+	mockUploader := &mockUploader{
+		uploadFn: func(ctx aws.Context, input *s3manager.UploadInput, opts ...func(*s3manager.Uploader)) (*s3manager.UploadOutput, error) {
+			if *input.Bucket != bucket {
+				t.Errorf("expected bucket to be %q, got %q", bucket, *input.Bucket)
+			}
+			if *input.Key != key {
+				t.Errorf("expected key to be %q, got %q", key, *input.Key)
+			}
+			if input.Body == nil {
+				t.Errorf("expected body to be non-nil")
+			}
+			return &s3manager.UploadOutput{}, nil
+		},
+	}
+
+	client := &S3Client{
+		region:    region,
+		accessKey: accessKey,
+		secretKey: secretKey,
+		bucket:    bucket,
+		key:       key,
+		uploader:  mockUploader,
+	}
+
+	reader := strings.NewReader("test data")
+	err := client.Upload(context.Background(), reader)
+	if err != nil {
+		t.Fatalf("Unexpected error: %v", err)
+	}
+}
+
+func TestS3ClientUploadFail(t *testing.T) {
+	region := "us-west-2"
+	accessKey := "your-access-key"
+	secretKey := "your-secret-key"
+	bucket := "your-bucket"
+	key := "your/key/path"
+
+	mockUploader := &mockUploader{
+		uploadFn: func(ctx aws.Context, input *s3manager.UploadInput, opts ...func(*s3manager.Uploader)) (*s3manager.UploadOutput, error) {
+			return &s3manager.UploadOutput{}, fmt.Errorf("some error related to S3")
+		},
+	}
+
+	client := &S3Client{
+		region:    region,
+		accessKey: accessKey,
+		secretKey: secretKey,
+		bucket:    bucket,
+		key:       key,
+		uploader:  mockUploader,
+	}
+
+	reader := strings.NewReader("test data")
+	err := client.Upload(context.Background(), reader)
+	if err == nil {
+		t.Fatal("Expected error, got nil")
+	}
+	if !strings.Contains(err.Error(), "some error related to S3") {
+		t.Fatalf("Expected error to contain %q, got %q", "some error related to S3", err.Error())
+	}
+}
+
+type mockUploader struct {
+	uploadFn func(ctx aws.Context, input *s3manager.UploadInput, opts ...func(*s3manager.Uploader)) (*s3manager.UploadOutput, error)
+}
+
+func (m *mockUploader) UploadWithContext(ctx aws.Context, input *s3manager.UploadInput, opts ...func(*s3manager.Uploader)) (*s3manager.UploadOutput, error) {
+	if m.uploadFn != nil {
+		return m.uploadFn(ctx, input, opts...)
 	}
+	return &s3manager.UploadOutput{}, nil
 }