$ref resolver and expander: canonicalize $ref and basepath

[fredbi]

• added special handling for $ref support on windows (fixed failing edge cases)

• enabled Appveyor CI for windows

• fixes #97

URL normalization is a key part of the expansion process. Reformulating how URI normalization is carried out is a pre-requisite to properly handle the specifics of file $ref's on windows.

Options handling

• refactored options and defaults for readability
  • perform shallow clone of options to avoid propagating internal changes to the caller. It is now safe to reuse the passed options for subsequent calls
  • systematically canonicalize the input RelativeBase
  • when no relative base is passed, ensure in all situations that the base is a virtual in memory root document at file://{cwd}/.root. All specs without remote $ref should be able to resolve/expand without any RelativeBase.

Ref normalizer

• refactored the normalizer for readability and cross-platform support
• input URIs to the expander and resolver are now systematically canonicalized before internal use
• file $ref's and input RelativeBase are normalized with the "file://" scheme
• windows-specifics are handled separately: windows path and their quirks (case insensitive, backslashes, drive letter, shared volumes) are normalized during the canonicalization of the RelativeBase and every encountered $ref
• the internals of $ref handling (for caching, cycle detection, rebasing) are largely simplified following this uniform canonicalization

Tests

• added more thorough assertions on all expanded results:
  • if some $ref remain after expansion (i.e. circulars), check that they all Resolve and Expand properly
• added more tests for windows $ref
• added more test helpers to scan for $ref in a document and test those
• added a complex spec that exhibits complex circular $ref patterns (Azure network)
• beefed up unit testing for the normalization process

Signed-off-by: Frederic BIDON fredbi@yahoo.com

added azure testcase

Signed-off-by: Frederic BIDON fredbi@yahoo.com

[codecov[bot]]

Codecov Report

Merging #141 (8f0170e) into master (eb3c5a0) will increase coverage by 0.76%. The diff coverage is 88.23%.

@@            Coverage Diff             @@
##           master     #141      +/-   ##
==========================================
+ Coverage   62.18%   62.95%   +0.76%     
==========================================
  Files          27       28       +1     
  Lines        2052     2054       +2     
==========================================
+ Hits         1276     1293      +17     
+ Misses        605      592      -13     
+ Partials      171      169       -2     

Impacted Files	Coverage Δ
resolver.go	60.00% <14.28%> (+3.13%)	:arrow_up:
normalizer_nonwindows.go	62.50% <62.50%> (ø)
schema_loader.go	87.14% <86.20%> (-1.10%)	:arrow_down:
normalizer.go	95.58% <95.31%> (+12.00%)	:arrow_up:
debug.go	100.00% <100.00%> (ø)
expander.go	81.09% <100.00%> (+2.51%)	:arrow_up:

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