Add test cases for GCS

[nakabonne]

What this PR does / why we need it:

Which issue(s) this PR fixes:

Fixes #801

Does this PR introduce a user-facing change?:

NONE

[pipecd-bot]

Code coverage for golang is 21.47%. This pull request increases coverage by 0.24%.

File	Function	Base	Head	Diff
pkg/filestore/gcs/gcs.go	Store.GetObject	71.43%	78.57%	+7.14%
pkg/filestore/gcs/gcs.go	Store.PutObject	0.00%	57.14%	+57.14%
pkg/filestore/gcs/gcs.go	Store.ListObjects	0.00%	84.62%	+84.62%
pkg/filestore/gcs/gcs.go	Store.Close	0.00%	100.00%	+100.00%
pkg/filestore/gcs/gcs.go	Store.NewReader	42.86%	71.43%	+28.57%

[nghialv]

nit: Remove empty line.

[nakabonne]

Fixed

[nghialv]

Thank you.
/approve

[pipecd-bot]

Code coverage for golang is 21.47%. This pull request increases coverage by 0.24%.

File	Function	Base	Head	Diff
pkg/filestore/gcs/gcs.go	Store.NewReader	42.86%	71.43%	+28.57%
pkg/filestore/gcs/gcs.go	Store.GetObject	71.43%	78.57%	+7.14%
pkg/filestore/gcs/gcs.go	Store.PutObject	0.00%	57.14%	+57.14%
pkg/filestore/gcs/gcs.go	Store.ListObjects	0.00%	84.62%	+84.62%
pkg/filestore/gcs/gcs.go	Store.Close	0.00%	100.00%	+100.00%

[nakabonne]

/trigger build

[pipecd-bot]

@nakabonne: Your requested build has been scheduled in response to this comment.

[nakabonne]

/trigger test

[pipecd-bot]

@nakabonne: Your requested test has been scheduled in response to this comment.

[nakabonne]

/trigger build

[pipecd-bot]

@nakabonne: Your requested build has been scheduled in response to this comment.

[pipecd-bot]

Code coverage for golang is 21.47%. This pull request increases coverage by 0.24%.

File	Function	Base	Head	Diff
pkg/filestore/gcs/gcs.go	Store.PutObject	0.00%	57.14%	+57.14%
pkg/filestore/gcs/gcs.go	Store.ListObjects	0.00%	84.62%	+84.62%
pkg/filestore/gcs/gcs.go	Store.Close	0.00%	100.00%	+100.00%
pkg/filestore/gcs/gcs.go	Store.NewReader	42.86%	71.43%	+28.57%
pkg/filestore/gcs/gcs.go	Store.GetObject	71.43%	78.57%	+7.14%

[nakabonne]

/approve

[pipecd-bot]

This pull request is APPROVED by nakabonne.

Approvers can cancel the approval by writing /approve cancel in a comment. Any additional commits also will change this pull request to be not-approved.