Add PDF detection

lib/linguist/blob_helper.rb

@@ -158,6 +158,13 @@ module Linguist
       extname.downcase == '.stl'
     end
 
+    # Public: Is the blob a PDF?
+    #
+    # Return true or false
+    def pdf?
+      extname.downcase == '.pdf'
+    end
+
     MEGABYTE = 1024 * 1024
 
     # Public: Is the blob too big to load?

test/test_blob.rb

@@ -137,6 +137,10 @@ class TestBlob < Test::Unit::TestCase
     assert blob("Text/cube.stl").solid?
   end
 
+  def test_pdf
+    assert blob("Binary/foo.pdf").pdf?
+  end
+
   def test_viewable
     assert blob("Text/README").viewable?
     assert blob("Ruby/foo.rb").viewable?