BJ266-4: Add unit-test for apis/opts/ports.go, fix #1906

[devily]

Ⅰ. Describe what this PR did

New ports and expose ports interface.

Ⅱ. Does this pull request fix one issue?

fix #1906

Ⅲ. Describe how you did it

Add one correct test case and two incorrect test case.

Ⅳ. Describe how to verify it

Ⅴ. Special notes for reviews

[CLAassistant]

All committers have signed the CLA.

[pouchrobot]

@devily Thanks for your contribution. 🍻
Please sign off in each of your commits.

[pouchrobot]

We found this is your first time to contribute to Pouch, @devily
👏 We really appreciate it.
Just remind that you have read the contribution guide: https://github.com/alibaba/pouch/blob/master/CONTRIBUTING.md
If you didn't, you should do that first. If done, welcome again and please enjoy hacking! 🍻

[codecov-io]

Codecov Report

Merging #1976 into master will increase coverage by 0.09%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1976      +/-   ##
==========================================
+ Coverage   63.31%   63.41%   +0.09%     
==========================================
  Files         200      200              
  Lines       15522    15522              
==========================================
+ Hits         9828     9843      +15     
+ Misses       4455     4437      -18     
- Partials     1239     1242       +3

Flag	Coverage Δ
#criv1alpha1test	33.82% <ø> (-0.04%)	⬇️
#criv1alpha2test	34.28% <ø> (ø)	⬆️
#integrationtest	38.42% <ø> (-0.01%)	⬇️
#unittest	20.99% <ø> (+0.13%)	⬆️

Impacted Files	Coverage Δ
ctrd/watch.go	72.72% <0%> (-3.04%)	⬇️
daemon/mgr/container.go	53.85% <0%> (-0.16%)	⬇️
cri/stream/httpstream/spdy/upgrade.go	60% <0%> (+5.71%)	⬆️
apis/opts/ports.go	73.91% <0%> (+73.91%)	⬆️