Fix: A single-file app can have CRLF and random YAML documents order

[silvin-lubecki]

- What I did

Fix CRLF detection on single-file app (https://github.com/docker/app/issues/553) Fix YAML documents order detection for single-file apps (https://github.com/docker/app/issues/249)

• Split and Merge remembers the CRLF detection while outputting the result

- How to verify it Add e2e tests:

• split/merge a single file with CRLF
• render a single file with documents in random order

- Description for the changelog

• Fix CRLF detection on single-file app
• Fix YAML documents order detection for single-file apps

- A picture of a cute animal (not mandatory but encouraged)

[codecov[bot]]

Codecov Report

Merging #561 into master will not change coverage. The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #561   +/-   ##
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  Coverage   71.23%   71.23%           
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  Files          55       55           
  Lines        3306     3306           
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  Hits         2355     2355           
  Misses        650      650           
  Partials      301      301

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[thaJeztah]

Did a quick check what the YAML spec says about newlines; https://yaml.org/spec/1.0/#id2565848

Inside all scalar nodes, a compliant YAML processor must translate the two-character combination CR LF, any CR that is not followed by an LF, and any NEL into a single LF (this does not apply to escaped characters). LS and PS characters are preserved. These rules are compatible with Unicode's newline guidelines.

[silvin-lubecki]

Yes but I used the 1.2 version of the specs https://yaml.org/spec/1.2/spec.html#id2774608 says CRLF is a valid line break:

YAML recognizes the following ASCII line break characters. [24] b-line-feed ::= #xA / LF */
[25] b-carriage-return ::= #xD / CR */
[26] b-char ::= b-line-feed | b-carriage-return

[silvin-lubecki]

@jcsirot @rumpl PTAL

[silvin-lubecki]

PTAL @chris-crone