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 DataKinds #-}
  {-# LANGUAGE OverloadedStrings #-}
  {-# LANGUAGE ScopedTypeVariables #-}
  
  module Main where
  
  import Control.Monad.IO.Class (liftIO)
  import Data.Int (Int64)
  import Test.Framework (defaultMain, Test)
  import TensorFlow.Types (ListOf(..), Scalar(..), (/:/))
  import TensorFlow.Ops (scalar)
  import TensorFlow.Queue
  import TensorFlow.Session
      ( asyncProdNodes
      , build
      , run
      , runSession
      , run_
      )
  import Test.Framework.Providers.HUnit (testCase)
  import Test.HUnit ((@=?))
  import qualified Data.ByteString as BS
  
  -- | Test basic queue behaviors.
  testBasic :: Test
  testBasic = testCase "testBasic" $ runSession $ do
      q :: Queue [Int64, BS.ByteString] <- build $ makeQueue 1 ""
      run_ =<< enqueue q (42 :/ scalar "Hi" :/ Nil)
      x <- run =<< dequeue q
      liftIO $ (Scalar 42 /:/ Scalar "Hi" /:/ Nil) @=? x
  
      run_ =<< enqueue q (56 :/ scalar "Bar" :/ Nil)
      y <- run =<< dequeue q
      -- Note: we use explicit "Scalar" here to specify the type that was
      -- fetched.  Equivalently we could write
      -- 56 /:/ "Bar" /:/ Nil :: List [Scalar Int64, Scalar BS.ByteString]
      -- or else allow the types to be determined by future use of the fetched
      -- value.
      let expected = Scalar 56 /:/ Scalar "Bar" /:/ Nil
      liftIO $ expected @=? y
  
  -- | Test queue pumping.
  testPump :: Test
  testPump = testCase "testPump" $ runSession $ do
      (deq, pump) <- build $ do
          q :: Queue [Int64, BS.ByteString] <- makeQueue 2 "ThePumpQueue"
          (,) <$> dequeue q
              <*> enqueue q (31 :/ scalar "Baz" :/ Nil)
      -- This is a realistic use. The pump inputs are pre-bound to some
      -- nodes that produce values when pumped (e.g. read from a
      -- file).
      run_ (pump, pump)
  
      (x, y) <- run (deq, deq)
      let expected = Scalar 31 /:/ Scalar "Baz" /:/ Nil
      liftIO $ expected @=? x
      liftIO $ expected @=? y
  
  testAsync :: Test
  testAsync = testCase "testAsync" $ runSession $ do
      (deq, pump) <- do
          q :: Queue [Int64, BS.ByteString] <- makeQueue 2 ""
          (,) <$> dequeue q
              <*> enqueue q (10 :/ scalar "Async" :/ Nil)
      -- Pumps the queue until canceled by runSession exiting.
      asyncProdNodes pump
      -- Picks up a couple values and verifies they are as expected.
      let expected = Scalar 10 /:/ Scalar "Async" /:/ Nil
      run deq >>= liftIO . (expected @=?)
      run deq >>= liftIO . (expected @=?)
  
  main :: IO ()
  main = defaultMain
              [ testBasic
              , testPump
              , testAsync
              ]
  