TypeError is appropriate here

Library/Homebrew/dependency_collector.rb

@@ -59,7 +59,7 @@ class DependencyCollector
     when Class
       parse_class_spec(spec, tag)
     else
-      raise "Unsupported type #{spec.class} for #{spec}"
+      raise TypeError, "Unsupported type #{spec.class} for #{spec}"
     end
   end
 
@@ -99,7 +99,7 @@ class DependencyCollector
     if spec < Requirement
       spec.new(tag)
     else
-      raise "#{spec} is not a Requirement subclass"
+      raise TypeError, "#{spec} is not a Requirement subclass"
     end
   end
 

Library/Homebrew/test/test_dependency_collector.rb

@@ -110,4 +110,12 @@ class DependencyCollectorTests < Test::Unit::TestCase
     MacOS.stubs(:version).returns(MacOS::Version.new(10.7))
     assert_equal X11Dependency::Proxy.new(:libpng), @d.build(:libpng)
   end
+
+  def test_raises_typeerror_for_unknown_classes
+    assert_raises(TypeError) { @d.add(Class.new) }
+  end
+
+  def test_raises_typeerror_for_unknown_types
+    assert_raises(TypeError) { @d.add(Object.new) }
+  end
 end