Environment Information

JRuby version and operating system:

• jruby 9.2.14.0 (2.5.7) 2020-12-08 ebe64ba OpenJDK 64-Bit Server VM 25.275-b01 on 1.8.0_275-b01 +jit [mswin32-x86_64]
• jruby 9.3.0.0-SNAPSHOT (2.6.5) 2020-12-28 0864236 OpenJDK 64-Bit Server VM 25.275-b01 on 1.8.0_275-b01 +jit [mswin32-x86_64]

Other relevant info:

• I think this is another instance of open3.rb broken in JRuby #5018

Expected Behavior

GIVEN the following Ruby code running in JRuby on Windows

AND the following statement succeeds:

output = IO.popen(["gem.bat", "build", "-V", "jruby_test.gemspec"], &:read)

AND the PATHEXT environment variable is set to .COM;.EXE;.BAT;.CMD;.VBS;.VBE;.JS;.JSE;.WSF;.WSH;.MSC;.CPL

Then following statement (which omits the ".bat" extension) should also succeed:

output = IO.popen(["gem", "build", "-V", "jruby_test.gemspec"], &:read)

I noticed this in my CI job for my gem. I do not have a windows box to test this on, but was able to duplicate this using GitHub Actions using a Windows VM:

https://github.com/jcouball/jruby_test/blob/main/Rakefile#L7

In JRuby on Windows, the popen_test_1 rake task succeeds and the popen_test_2 rake task fails.

Actual Behavior

The second command fails with the error:

IOError: Cannot run program "gem" (in directory "D:\a\jruby_test\jruby_test"): CreateProcess error=2, The system cannot find the file specified