[BE]: (zip file decompress task ) add Unit test with mocking GCP CloudTasks client #149
Description
What
Add unit test for /infrastructure/gcp/cloudtasks.go.
This task has something to do with #127 . Since it's not complicated task and also google's official example also uses actual CloudTasks for testing, ( https://github.com/GoogleCloudPlatform/golang-samples/blob/23529a7f7c197213f71e07d506c33b36924585b2/appengine/go11x/tasks/create_task/create_task_test.go#L24 ), this task has lower priority.