combine errors to a single if-statement. fix spec test

Library/Homebrew/cask/lib/hbc/cli/internal_stanza.rb

@@ -71,16 +71,16 @@ module Hbc
             next
           end
 
-          if value.nil? || (value.is_a?(Array) && value.empty?)
-            opoo "no such stanza '#{stanza}' on Cask '#{cask}'" unless quiet?
-            puts ""
-            raise ArgumentError, "no such stanza '#{stanza}' on Cask '#{cask}'"
-          end
+          if (value.nil? || value.is_a?(Array) && value.empty?) ||
+             (artifact_name && !value.key?(artifact_name))
 
-          if artifact_name && !value.key?(artifact_name)
-            opoo "no such stanza '#{artifact_name}' on Cask '#{cask}'" unless quiet?
-            puts ""
-            raise ArgumentError, "no such stanza '#{artifact_name}' on Cask '#{cask}'"
+            if artifact_name
+              thing = artifact_name
+            else
+              thing = stanza
+            end
+
+            raise CaskError, "no such stanza '#{thing}' on Cask '#{cask}'"
           end
 
           if stanza == :artifacts

Library/Homebrew/test/cask/cli/internal_stanza_spec.rb

@@ -1,8 +1,9 @@
 describe Hbc::CLI::InternalStanza, :cask do
   it "shows stanza of the Specified Cask" do
     command = described_class.new("gpg", "with-gpg")
-    command.run
-    # TODO: check result
+    expect do
+      command.run
+    end.to output("http://example.com/gpg-signature.asc\n").to_stdout
   end
 
   it "raises an exception when stanza is invalid" do