feat: download file

gcs_manager.go

@@ -18,6 +18,7 @@ type (
 		ListFiles(bucketName string) ([]string, error)
 		MoveFile(bucketName, srcObjectName, dstObjectName string) error
 		DeleteAllFilesInDirectory(bucketName, directory string) error
+		DownloadFile(bucketName, objectName, destPath string) error
 	}
 
 	gcsManager struct {
@@ -118,3 +119,22 @@ func (g gcsManager) DeleteAllFilesInDirectory(bucketName, directory string) erro
 
 	return nil
 }
+
+func (g gcsManager) DownloadFile(bucketName, objectName, destPath string) error {
+	bucket := g.client.Bucket(bucketName)
+	obj := bucket.Object(objectName)
+	r, err := obj.NewReader(g.ctx)
+	if err != nil {
+		return err
+	}
+	defer r.Close()
+
+	out, err := os.Create(destPath)
+	if err != nil {
+		return err
+	}
+	defer out.Close()
+
+	_, err = io.Copy(out, r)
+	return err
+}

gcs_manager_test.go

@@ -71,3 +71,14 @@ func TestDeleteAllFilesInDirectory(t *testing.T) {
 	err := mockGCS.DeleteAllFilesInDirectory("bucketName", "directory/")
 	assert.NoError(t, err)
 }
+
+func TestDownloadFile(t *testing.T) {
+	ctrl := gomock.NewController(t)
+	defer ctrl.Finish()
+
+	mockGCS := NewMockGCSManager(ctrl)
+	mockGCS.EXPECT().DownloadFile("bucketName", "directory/file.ext", "/tmp/").Return(nil)
+
+	err := mockGCS.DownloadFile("bucketName", "directory/file.ext", "/tmp/")
+	assert.NoError(t, err)
+}