Allow multiple JSON outputs

Library/Homebrew/test/cmd/outdated_spec.rb

@@ -6,7 +6,7 @@
 RSpec.describe Homebrew::Cmd::Outdated do
   it_behaves_like "parseable arguments"
 
-  it "outputs JSON", :integration_test do
+  it "outputs JSON", :integration_test, :skip_generic do
     setup_test_formula "testball"
     (HOMEBREW_CELLAR/"testball/0.0.1/foo").mkpath
 
@@ -20,9 +20,13 @@
       }],
       casks:    [],
     })
+    # json v2.8.1 is inconsistent it how it renders empty arrays,
+    # for now we allow multiple outputs:
+    alternate_json = expected_json.gsub("[]", "[\n\n]")
 
     expect { brew "outdated", "--json=v2" }
-      .to output("#{expected_json}\n").to_stdout
-      .and be_a_success
+      .to(output("#{expected_json}\n").to_stdout
+      .or(output("#{alternate_json}\n").to_stdout)
+      .and(be_a_success))
   end
 end