testPreexisting :: IO ()
testPreexisting = 
  do (filename1,_) <- deleteFiles
     Bytes.writeFile filename1 "previous content\n"
     let content1 = "1 new content"
         content2 = "2 new content"
     bytes <- tailToIORef (\filepath -> 
                              do catToFile filepath content1
                                 halfsec
                                 catToFile filepath content2)
                          filename1
     assertEqual "" (newlines [content1,content2]) bytes
testPreexisting :: IO ()
testPreexisting = 
  do (filename1,_) <- deleteFiles
     Bytes.writeFile filename1 "previous content\n"
     let content1 = "1 new content"
         content2 = "2 new content"
     bytes <- tailToIORef (\filepath -> 
                              do catToFile filepath content1
                                 halfsec
                                 catToFile filepath content2)
                          filename1
     assertEqual "" (newlines [content1,content2]) bytes
testPreexisting = 
  do (filename1,_) <- deleteFiles
     Bytes.writeFile filename1 "previous content\n"
     let content1 = "1 new content"
         content2 = "2 new content"
     bytes <- tailToIORef (\filepath -> 
                              do catToFile filepath content1
                                 halfsec
                                 catToFile filepath content2)
                          filename1
     assertEqual "" (newlines [content1,content2]) bytes