Attachment unit test cases in SODA API pkg/controller

[nguptaopensds]

What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespace from that line:

/kind new feature /kind bug fix /kind cleanup /kind revert change /kind design /kind documentation

/kind enhancement

What this PR does / why we need it: This PR is adding the unit test cases for attachment.go in pkg/controller

Which issue(s) this PR fixes:

Fixes #

Test Report Added?:

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespace from that line: /kind TESTED /kind NOT-TESTED

Test Report:

Special notes for your reviewer:

[nguptaopensds]

@NajmudheenCT please check once

[codecov-commenter]

Codecov Report

Merging #1287 into master will decrease coverage by 2.12%. The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1287      +/-   ##
==========================================
- Coverage   41.48%   39.36%   -2.13%     
==========================================
  Files          53       53              
  Lines        7752     6966     -786     
==========================================
- Hits         3216     2742     -474     
+ Misses       4021     3692     -329     
- Partials      515      532      +17     

Impacted Files	Coverage Δ
client/volume.go	62.31% <0.00%> (-8.40%)	:arrow_down:
client/fileshare.go	65.95% <0.00%> (-7.22%)	:arrow_down:
client/dock.go	42.85% <0.00%> (-7.15%)	:arrow_down:
client/pool.go	42.85% <0.00%> (-7.15%)	:arrow_down:
client/host.go	61.11% <0.00%> (-6.98%)	:arrow_down:
client/version.go	46.15% <0.00%> (-6.79%)	:arrow_down:
client/profile.go	55.55% <0.00%> (-6.42%)	:arrow_down:
pkg/api/policy/policy.go	25.88% <0.00%> (-5.19%)	:arrow_down:
pkg/api/controllers/version.go	65.21% <0.00%> (-4.02%)	:arrow_down:
pkg/api/controllers/base.go	76.74% <0.00%> (-3.26%)	:arrow_down:
... and 43 more