Change behaviour of 'cask _stanza' command. Add tests for 'cask _stanza' command

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

@@ -71,10 +71,16 @@ module Hbc
             next
           end
 
+          if value == nil || (value.kind_of?(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 artifact_name && !value.key?(artifact_name)
             opoo "no such stanza '#{artifact_name}' on Cask '#{cask}'" unless quiet?
             puts ""
-            next
+            raise ArgumentError, "no such stanza '#{artifact_name}' on Cask '#{cask}'"
           end
 
           if stanza == :artifacts

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

@@ -0,0 +1,28 @@
+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
+  end
+
+  it "raises an exception when stanza is invalid" do
+    expect {
+     described_class.new("invalid_stanza", "with-gpg");
+    }.to raise_error(/Illegal stanza/);
+  end
+
+  it "raises an exception when normal stanza is not present on cask" do
+     command = described_class.new("caveats", "with-gpg");
+     expect {
+       command.run
+     }.to raise_error(/no such stanza/)
+  end
+
+  it "raises an exception when artifact stanza is not present on cask" do
+     command = described_class.new("zap", "with-gpg");
+     expect {
+       command.run
+     }.to raise_error(/no such stanza/)
+  end
+end