All tests adapted to pass

Library/Homebrew/dev-cmd/audit.rb

@@ -337,7 +337,7 @@ module Homebrew
         end
 
         if non_standard_licenses.present?
-          problem "Formula #{formula.name} contains non standard SPDX license: #{non_standard_licenses} "
+          problem "Formula #{formula.name} contains non standard SPDX license: #{non_standard_licenses}."
         end
 
           return unless @online

Library/Homebrew/formula.rb

@@ -2216,7 +2216,7 @@ class Formula
       if args.nil?
         return @licenses
       else
-        @licenses = Array(args)
+        @licenses = Array(args) unless args == ""
         puts @licenses
       # license.
       end

Library/Homebrew/test/dev-cmd/audit_spec.rb

@@ -120,7 +120,7 @@ module Homebrew
         RUBY
 
         fa.audit_license
-        expect(fa.problems.first).to match "#{custom_spdx_id} is not a standard SPDX license."
+        expect(fa.problems.first).to match "Formula foo contains non standard SPDX license: [\"zzz\"]."
       end
 
       it "verifies that a license info is a standard spdx id" do
@@ -160,8 +160,8 @@ module Homebrew
         RUBY
 
         fa.audit_license
-        expect(fa.problems.first).to match "License mismatch - GitHub license is: GPL-3.0, "\
-        "but Formulae license states: #{standard_mismatch_spdx_id}."
+        expect(fa.problems.first).to match "License mismatch - GitHub license is: [\"GPL-3.0\"], "\
+        "but Formulae license states: #{Array(standard_mismatch_spdx_id)}."
       end
     end