Convert brew services test to spec.

Library/Homebrew/test/cmd/services_spec.rb

@@ -0,0 +1,10 @@
+describe "brew services", :integration_test, :needs_macos, :needs_official_cmd_taps do
+  it "allows controlling services" do
+    setup_remote_tap "homebrew/services"
+
+    expect { brew "services", "list" }
+      .to output("Warning: No services available to control with `brew services`\n").to_stderr
+      .and not_to_output.to_stdout
+      .and be_a_success
+  end
+end

Library/Homebrew/test/services_test.rb

@@ -1,11 +0,0 @@
-require "testing_env"
-
-class IntegrationCommandTestServices < IntegrationCommandTestCase
-  def test_services
-    needs_test_cmd_taps
-    needs_macos
-    setup_remote_tap("homebrew/services")
-    assert_equal "Warning: No services available to control with `brew services`",
-      cmd("services", "list")
-  end
-end