diff --git a/Library/Homebrew/test/bottle_test.rb b/Library/Homebrew/test/bottle_test.rb
index c10746e098d4e59af25ab67af2395364fd6c66ac..7981ccf79af4f33ab1168782371f1bf7fd7ca01e 100644
--- a/Library/Homebrew/test/bottle_test.rb
+++ b/Library/Homebrew/test/bottle_test.rb
@@ -14,7 +14,7 @@ class IntegrationCommandTestBottle < IntegrationCommandTestCase
       FileUtils.ln_s "not-exist", "symlink"
     end
     assert_match(/testball-0\.1.*\.bottle\.tar\.gz/,
-                  cmd_output("bottle", "--no-rebuild", "testball"))
+                  cmd("bottle", "--no-rebuild", "testball"))
   ensure
     FileUtils.rm_f Dir["testball-0.1*.bottle.tar.gz"]
   end
diff --git a/Library/Homebrew/test/options_test.rb b/Library/Homebrew/test/options_test.rb
index f38ec441546e7675dfdbe281ca2689e48ff08e58..09ea14180e970e53ec8253b5228475c545e79ba4 100644
--- a/Library/Homebrew/test/options_test.rb
+++ b/Library/Homebrew/test/options_test.rb
@@ -9,7 +9,7 @@ class IntegrationCommandTestOptions < IntegrationCommandTestCase
     EOS
 
     assert_equal "--with-foo\n\tBuild with foo\n--without-bar\n\tBuild without bar support",
-      cmd_output("options", "testball").chomp
+      cmd("options", "testball").chomp
   end
 end
 
diff --git a/Library/Homebrew/test/support/helper/integration_command_test_case.rb b/Library/Homebrew/test/support/helper/integration_command_test_case.rb
index a36b5669161033e8411f323b5ecf8162d3d40a72..45e73757a16531dbfa87a0a5821cba5100852e02 100644
--- a/Library/Homebrew/test/support/helper/integration_command_test_case.rb
+++ b/Library/Homebrew/test/support/helper/integration_command_test_case.rb
@@ -3,6 +3,7 @@ require "fileutils"
 require "pathname"
 require "formula"
 require "test/support/helper/test_case"
+require "open3"
 
 class IntegrationCommandTestCase < Homebrew::TestCase
   def setup
@@ -28,57 +29,34 @@ class IntegrationCommandTestCase < Homebrew::TestCase
   end
 
   def cmd_output(*args)
-    # 1.8-compatible way of writing def cmd_output(*args, **env)
     env = args.last.is_a?(Hash) ? args.pop : {}
-    cmd_args = %W[
-      -W0
-      -I#{HOMEBREW_LIBRARY_PATH}/test/support/lib
-      -I#{HOMEBREW_LIBRARY_PATH}
-      -rconfig
+
+    env.merge!(
+      "HOMEBREW_BREW_FILE" => HOMEBREW_PREFIX/"bin/brew",
+      "HOMEBREW_INTEGRATION_TEST" => cmd_id_from_args(args),
+      "HOMEBREW_TEST_TMPDIR" => TEST_TMPDIR,
+      "HOMEBREW_DEVELOPER" => ENV["HOMEBREW_DEVELOPER"]
+    )
+
+    ruby_args = [
+      "-W0",
+      "-I", "#{HOMEBREW_LIBRARY_PATH}/test/support/lib",
+      "-I", HOMEBREW_LIBRARY_PATH.to_s,
+      "-rconfig"
     ]
-    if ENV["HOMEBREW_TESTS_COVERAGE"]
-      # This is needed only because we currently use a patched version of
-      # simplecov, and gems installed through git are not available without
-      # requiring bundler/setup first. See also the comment in test/Gemfile.
-      # Remove this line when we'll switch back to a stable simplecov release.
-      cmd_args << "-rbundler/setup"
-      cmd_args << "-rsimplecov"
-    end
-    cmd_args << "-rtest/support/helper/integration_mocks"
-    cmd_args << (HOMEBREW_LIBRARY_PATH/"brew.rb").resolved_path.to_s
-    cmd_args += args
-    developer = ENV["HOMEBREW_DEVELOPER"]
-    Bundler.with_original_env do
-      ENV["HOMEBREW_BREW_FILE"] = HOMEBREW_PREFIX/"bin/brew"
-      ENV["HOMEBREW_INTEGRATION_TEST"] = cmd_id_from_args(args)
-      ENV["HOMEBREW_TEST_TMPDIR"] = TEST_TMPDIR
-      ENV["HOMEBREW_DEVELOPER"] = developer
-      env.each_pair do |k, v|
-        ENV[k] = v
-      end
+    ruby_args << "-rsimplecov" if ENV["HOMEBREW_TESTS_COVERAGE"]
+    ruby_args << "-rtest/support/helper/integration_mocks"
+    ruby_args << (HOMEBREW_LIBRARY_PATH/"brew.rb").resolved_path.to_s
 
-      read, write = IO.pipe
-      begin
-        pid = fork do
-          read.close
-          $stdout.reopen(write)
-          $stderr.reopen(write)
-          write.close
-          exec RUBY_PATH, *cmd_args
-        end
-        write.close
-        read.read.chomp
-      ensure
-        Process.wait(pid)
-        read.close
-      end
+    Bundler.with_original_env do
+      output, status = Open3.capture2e(env, RUBY_PATH, *ruby_args, *args)
+      [output.chomp, status]
     end
   end
 
   def cmd(*args)
-    output = cmd_output(*args)
-    status = $?.exitstatus
-    assert_equal 0, status, <<-EOS.undent
+    output, status = cmd_output(*args)
+    assert status.success?, <<-EOS.undent
       `brew #{args.join " "}` exited with non-zero status!
       #{output}
     EOS
@@ -86,9 +64,8 @@ class IntegrationCommandTestCase < Homebrew::TestCase
   end
 
   def cmd_fail(*args)
-    output = cmd_output(*args)
-    status = $?.exitstatus
-    refute_equal 0, status, <<-EOS.undent
+    output, status = cmd_output(*args)
+    refute status.success?, <<-EOS.undent
       `brew #{args.join " "}` exited with zero status!
       #{output}
     EOS