Fix a failing test

[mrkn]

This commit fixes the following failure:

  1) Failure:
Fiddle::TestImport#test_no_message_with_debug [/Users/mrkn/src/github.com/ruby/fiddle/test/fiddle/test_import.rb:152]:

1. [2/2] Assertion for "stderr"
   | <[]> expected but was
   | <["Exception `NameError' at /Users/mrkn/.rbenv/versions/2.5.1/lib/ruby/2.5.0/fiddle/import.rb:157 - uninitialized constant Fiddle::Function::STDCALL"]>.

[nobu]

Seems the bundled fiddle is called.
Don't mind it, my mistake.

[nobu]

I suspect that this failure is caused by a bug in bundler; bundler/setup.rb enables bundler even if rubygems is disabled.

[mrkn]

@nobu I just remove -rbundler/setup from RUBYOPT instead of using Bundler.with_clean_env.

[mrkn]

Oh...

[kou]

How about disabling all RUBYOPT and RUBYLIB in this test? It's simpler and more stable.

This works even if a developer has the following ugly RUBYOPT:

$ cat /tmp/warn.rb
$, = "XXX"
$ RUBYOPT=-r/tmp/warn.rb rake

diff --git a/test/fiddle/test_import.rb b/test/fiddle/test_import.rb
index 99294ea..db58a82 100644
--- a/test/fiddle/test_import.rb
+++ b/test/fiddle/test_import.rb
@@ -149,7 +149,21 @@ module Fiddle
     end
 
     def test_no_message_with_debug
-      assert_in_out_err(%w[--debug --disable=gems -rfiddle/import], 'p Fiddle::Importer', ['Fiddle::Importer'])
+      # disable all Ruby environment variables
+      orig_RUBYOPT, ENV['RUBYOPT'] = ENV['RUBYOPT'], nil
+      orig_RUBYLIB, ENV['RUBYLIB'] = ENV['RUBYLIB'], nil
+      libdir = File.expand_path('../../../lib', __FILE__)
+      assert_in_out_err([
+                          "--debug",
+                          "--disable=gems",
+                          "-I#{libdir}",
+                          "-rfiddle/import",
+                        ],
+                        'p Fiddle::Importer',
+                        ['Fiddle::Importer'])
+    ensure
+      ENV['RUBYLIB'] = orig_RUBYLIB
+      ENV['RUBYOPT'] = orig_RUBYOPT
     end
   end
 end if defined?(Fiddle)

[mrkn]

@kou thanks for your advice.
I pushed the new commit that follows your patch.

[kou]

+1

[nobu]

The first element of args to assert_in_out_err can be a Hash as environment variables.

[kou]

!!!
I've changed to use it.