[CS] Proper error handling when looking up grammars by URI

lib/ruby_speech/grxml.rb

@@ -31,7 +31,7 @@ def self.import(other)
       Element.import other
     end
 
-    URI_REGEX = /builtin:dtmf\/(?<type>\w*)(\?)?(?<query>(\w*=\w*;?)*)?/.freeze
+    URI_REGEX = /builtin:(?<class>.*)\/(?<type>\w*)(\?)?(?<query>(\w*=\w*;?)*)?/.freeze
 
     #
     # Fetch a builtin grammar by URI
@@ -42,12 +42,16 @@ def self.import(other)
     #
     def self.from_uri(uri)
       match = uri.match(URI_REGEX)
+      raise ArgumentError, "Only builtin grammars are supported" unless match
+      raise ArgumentError, "Only DTMF builtins are supported" unless match[:class] == 'dtmf'
+      type = match[:type]
       query = {}
       match[:query].split(';').each do |s|
         key, value = s.split('=')
         query[key] = value
       end
-      grammar = Builtins.send match[:type], query
+      raise ArgumentError, "#{type} is an invalid builtin grammar" unless Builtins.respond_to?(type)
+      Builtins.send type, query
     end
   end # GRXML
 end # RubySpeech

spec/ruby_speech/grxml_spec.rb

@@ -3,12 +3,32 @@
 module RubySpeech
   describe GRXML do
     describe ".from_uri" do
-      it "should fetch a simple builtin grammar by type" do
-        subject.from_uri("builtin:dtmf/phone").should == GRXML::Builtins.phone
+      context "with a builtin URI" do
+        it "should fetch a simple builtin grammar by type" do
+          subject.from_uri("builtin:dtmf/phone").should == GRXML::Builtins.phone
+        end
+
+        it "should fetch a parameterized builtin grammar" do
+          subject.from_uri("builtin:dtmf/boolean?y=3;n=4").should == GRXML::Builtins.boolean(y: 3, n: 4)
+        end
+
+        context "for speech" do
+          it "should raise ArgumentError" do
+            expect { subject.from_uri("builtin:speech/phone") }.to raise_error(ArgumentError, /Only DTMF/)
+          end
+        end
+
+        context "that doesn't exist" do
+          it "should raise ArgumentError" do
+            expect { subject.from_uri("builtin:dtmf/foobar") }.to raise_error(ArgumentError, /invalid/)
+          end
+        end
       end
 
-      it "should fetch a parameterized builtin grammar" do
-        subject.from_uri("builtin:dtmf/boolean?y=3;n=4").should == GRXML::Builtins.boolean(y: 3, n: 4)
+      context "with an http URI" do
+        it "should raise ArgumentError" do
+          expect { subject.from_uri("http://foo.com/grammar.grxml") }.to raise_error(ArgumentError, /builtin/)
+        end
       end
     end