Convert brew outdated test to spec.

Library/Homebrew/test/cmd/outdated_spec.rb

@@ -0,0 +1,11 @@
+describe "brew outdated", :integration_test do
+  it "prints outdated Formulae" do
+    setup_test_formula "testball"
+    (HOMEBREW_CELLAR/"testball/0.0.1/foo").mkpath
+
+    expect { brew "outdated" }
+      .to output("testball\n").to_stdout
+      .and not_to_output.to_stderr
+      .and be_a_success
+  end
+end

Library/Homebrew/test/outdated_test.rb

@@ -1,10 +0,0 @@
-require "testing_env"
-
-class IntegrationCommandTestOutdated < IntegrationCommandTestCase
-  def test_outdated
-    setup_test_formula "testball"
-    (HOMEBREW_CELLAR/"testball/0.0.1/foo").mkpath
-
-    assert_equal "testball", cmd("outdated")
-  end
-end