wrap $ref in allOf when readonly is set

[josephzidell]

Describe the PR
This PR adds functionality to support readonly $refs. It is supported by swagger, yet requires it to be wrapped in an allOf.

Relation issue
#1033

Additional context
Unfortunately, using readonly as a sibling to a $ref is ignored. The workaround is to wrap the $ref in an allOf. See this StackOverflow answer. I have confirmed that manually changing the swagger.json makes this work as expected.

[josephzidell]

I added a simple test confirming that setting readonly:"true" propagates (which we already know is the case, but seemed to have been missing a test case).

Can someone point me in the right direction as to a full test for this feature?

[codecov]

Codecov Report

Merging #1034 (3a62e1c) into master (0548f60) will increase coverage by 0.01%.
The diff coverage is 100.00%.

❗ Current head 3a62e1c differs from pull request most recent head eebd162. Consider uploading reports for the commit eebd162 to get more accurate results

@@            Coverage Diff             @@
##           master    #1034      +/-   ##
==========================================
+ Coverage   93.01%   93.02%   +0.01%     
==========================================
  Files           7        7              
  Lines        2005     2008       +3     
==========================================
+ Hits         1865     1868       +3     
  Misses         77       77              
  Partials       63       63              

Impacted Files	Coverage Δ
parser.go	93.50% <100.00%> (+0.02%)	⬆️

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[ubogdan]

@josephzidell, you need to write an additional unit test that will call parseStructField method to cover Line 1094 of parser.go.

[ubogdan]

@josephzidell We can't merge this PR until we have the unit tests and code coverage passing.

[josephzidell]

@ubogdan Understood. Unfortunately, I am feeling lost w/r to the style of unit tests in this repo. If someone can offer some guidance, I'd be happy to wrap this up.

[josephzidell]

@ubogdan Is this test in the right vicinity?

[ubogdan]

LGTM

[ubogdan]

@josephzidell Yes, it looks good enough to me. 😃
Thanks for your contribution.