Feature: Add Unit test and increase ci coverage.

[zzjin]

To more adapt release circle, we need more test codes to ensure new features/bugfixes not affect exists code and/or process.

Todo list:

• [x] add code coverage codes in ci progress. example:

go test -coverprofile=coverage.txt -covermode count `go list ./... | grep -v tests` -v 2>&1 | tee test_output.txt
cat test_output.txt | go-junit-report > report.xml
gocover-cobertura < coverage.txt > coverage.xml
gocov convert coverage.txt | gocov report

• [ ] fix failed tests
• [ ] add more unit test. files like below:

• pkg/utils
• pkg/remote
• ...

[cuisongliu]

The actions can add a test coverage test.