Highlight .gradle files as Groovy

test/test_blob.rb

@@ -255,6 +255,9 @@ class TestBlob < Test::Unit::TestCase
     # http://supercollider.sourceforge.net/
     # https://github.com/drichert/BCR2000.sc/blob/master/BCR2000.sc
     assert_equal Language['SuperCollider'], blob("BCR2000.sc").language
+
+    # https://github.com/gradleware/oreilly-gradle-book-examples/blob/master/ant-antbuilder/build.gradle
+    assert_equal Language['Groovy'], blob("build.gradle").language
   end
 
   def test_lexer