Gracefully handle a missing file command

lib/paperclip/content_type_detector.rb

@@ -49,8 +49,13 @@ module Paperclip
     end
 
     def type_from_file_command
-      # On BSDs, `file` doesn't give a result code of 1 if the file doesn't exist.
-      type = Paperclip.run("file", "-b --mime :file", :file => @filename)
+      type = begin
+        # On BSDs, `file` doesn't give a result code of 1 if the file doesn't exist.
+        Paperclip.run("file", "-b --mime :file", :file => @filename)
+      rescue Cocaine::CommandNotFoundError => e
+        SENSIBLE_DEFAULT
+      end
+
       if type.match(/\(.*?\)/)
         type = SENSIBLE_DEFAULT
       end

test/content_type_detector_test.rb

@@ -38,5 +38,11 @@ class ContentTypeDetectorTest < Test::Unit::TestCase
         Paperclip::ContentTypeDetector.new(@filename).detect
       end
     end
+
+    should 'return a sensible default when the file command is missing' do
+      Paperclip.stubs(:run).raises(Cocaine::CommandNotFoundError.new)
+      @filename = "/path/to/something"
+      assert_equal "application/octet-stream", Paperclip::ContentTypeDetector.new(@filename).detect
+    end
   end
 end