dev-cmd/update-maintainers: add tests

Library/Homebrew/test/dev-cmd/update-maintainers_spec.rb

@@ -0,0 +1,8 @@
+# typed: false
+# frozen_string_literal: true
+
+require "cmd/shared_examples/args_parse"
+
+describe "brew update-maintainers" do
+  it_behaves_like "parseable arguments"
+end

Library/Homebrew/test/utils/github_spec.rb

@@ -50,6 +50,13 @@ describe GitHub do
     end
   end
 
+  describe "::public_member_usernames", :needs_network do
+    it "gets the usernames of all publicly visible members of the organisation" do
+      response = described_class.public_member_usernames("Homebrew")
+      expect(response).to be_a(Array)
+    end
+  end
+
   describe "::sponsors_by_tier", :needs_network do
     it "errors on an unauthenticated token" do
       expect {