Incorrect expectations for ARGF.binmode behavior on Windows

[vais]

These two expectations are incorrect: https://github.com/ruby/spec/blob/master/core/argf/binmode_spec.rb#L15-L29

Basically, there is a file with Unix-style line breaks, and it is expecting that setting binmode will convert these Unix-style line endings into Windows-style line endings. That does not make any sense, because it's just not what binmode does. Per http://ruby-doc.org/core-2.0.0/ARGF.html#method-i-binmode

Puts ARGF into binary mode. Once a stream is in binary mode, it cannot be reset to non-binary mode. This option has the following effects:

• Newline conversion is disabled.
• Encoding conversion is disabled.
• Content is treated as ASCII-8BIT.

The proof is in the pudding:

C:\Users\Administrator\GitHub\spec>C:\Ruby\ruby-2.2.4-i386-mingw32\bin\ruby.exe -ve "ARGF.binmode; p ARGF.gets" C:\Users\Administrator\GitHub\spec\core\argf\fixtures\bin_file.txt
ruby 2.2.4p230 (2015-12-16 revision 53155) [i386-mingw32]
"test\n"

And here is the same result using ruby 1.8.7 (cause I wondered where these expectations came from, perhaps this is how it used to work on 1.8? But no.)

C:\Users\Administrator\GitHub\spec>C:\Ruby\ruby-1.8.7-p374-i386-mingw32\bin\ruby.exe -ve "ARGF.binmode; p ARGF.gets" C:\Users\Administrator\GitHub\spec\core\argf\fixtures\bin_file.txt
ruby 1.8.7 (2013-06-27 patchlevel 374) [i386-mingw32]
"test\n"

Ok, so to fix this and test ARGF.binmode properly, we need to add another fixture - a text file (named win_file.txt) containing Windows-style line breaks, then reading it in binmode should give us Windows-style line breaks, and reading it without binmode should give us Unix-style line endings:

C:\Users\Administrator\GitHub\spec>C:\Ruby\ruby-2.2.4-i386-mingw32\bin\ruby.exe -ve "ARGF.binmode; p ARGF.gets" C:\Users\Administrator\GitHub\spec\core\argf\fixtures\win_file.txt
ruby 2.2.4p230 (2015-12-16 revision 53155) [i386-mingw32]
"test\r\n"

C:\Users\Administrator\GitHub\spec>C:\Ruby\ruby-2.2.4-i386-mingw32\bin\ruby.exe -ve "p ARGF.gets" C:\Users\Administrator\GitHub\spec\core\argf\fixtures\win_file
.txt
ruby 2.2.4p230 (2015-12-16 revision 53155) [i386-mingw32]
"test\n"

@eregon unless there are any objections, I will be sending a PR for this, LMK...

[vais]

Just realized that the reason for this working incorrectly may have something to do with git or something else along the line having converted the line endings in the fixture file bin_file.txt from \r\n to \n.

[vais]

Yep, that was it - there's nothing wrong with the code, the problem was with the data (the fixture file). I replaced \ns with \r\ns in bin_file.txt and the spec makes sense again 😄

C:\Users\Administrator\GitHub\spec>..\mspec\bin\mspec core/argf/binmode_spec.rb
ruby 2.0.0p247 (2013-06-27) [i386-mingw32]
[| | ==================100%================== | 00:00:00]      0F      0E

Finished in 0.171600 seconds

1 file, 4 examples, 6 expectations, 0 failures, 0 errors, 0 tagged

One down, hundreds more to go 🍻

[eregon]

Good find! 356fa4f seems the culprit.