content: -- Copyright 2016 TensorFlow authors.
  --
  -- Licensed under the Apache License, Version 2.0 (the "License");
  -- you may not use this file except in compliance with the License.
  -- You may obtain a copy of the License at
  --
  --     http://www.apache.org/licenses/LICENSE-2.0
  --
  -- Unless required by applicable law or agreed to in writing, software
  -- distributed under the License is distributed on an "AS IS" BASIS,
  -- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  -- See the License for the specific language governing permissions and
  -- limitations under the License.
  
  {-# LANGUAGE OverloadedStrings #-}
  
  -- | Testing tracing.
  module Main where
  
  import Control.Concurrent.MVar (newEmptyMVar, putMVar, tryReadMVar)
  import Data.ByteString.Builder (toLazyByteString)
  import Data.ByteString.Lazy (isPrefixOf)
  import Data.Default (def)
  import Lens.Family2 ((&), (.~))
  import Test.Framework (defaultMain)
  import Test.Framework.Providers.HUnit (testCase)
  import Test.HUnit (assertBool, assertFailure)
  
  import qualified TensorFlow.Core as TF
  import qualified TensorFlow.Ops as TF
  
  testTracing :: IO ()
  testTracing = do
      -- Verifies that tracing happens as a side-effect of graph extension.
      loggedValue <- newEmptyMVar
      TF.runSessionWithOptions
          (def & TF.sessionTracer .~ putMVar loggedValue)
          (TF.run_ (TF.scalar (0 :: Float)))
      tryReadMVar loggedValue >>=
          maybe (assertFailure "Logging never happened") expectedFormat
    where expectedFormat x =
              let got = toLazyByteString x in
              assertBool ("Unexpected log entry " ++ show got)
                         ("Session.extend" `isPrefixOf` got)
  
  main :: IO ()
  main = defaultMain
      [ testCase "Tracing" testTracing
      ]
  