src/TSN/XML/Heartbeat.hs

   1 {-# LANGUAGE ScopedTypeVariables #-}
   2
   3 -- | Handle documents defined by Heartbeat.dtd.
   4 --
   5 module TSN.XML.Heartbeat (
   6   heartbeat_tests,
   7   verify )
   8 where
   9
  10 -- System imports.
  11 import Data.Tuple.Curry ( uncurryN )
  12 import Test.Tasty ( TestTree, testGroup )
  13 import Test.Tasty.HUnit ( (@?=), testCase )
  14 import Text.XML.HXT.Core (
  15   PU,
  16   unpickleDoc,
  17   XmlTree,
  18   xpTriple,
  19   xpElem,
  20   xpInt,
  21   xpText,
  22   xpWrap )
  23
  24 -- Local imports.
  25 import TSN.DbImport ( ImportResult(..) )
  26 import Xml ( pickle_unpickle, unpickleable )
  27
  28
  29 -- | The data structure that holds the XML representation of a
  30 --   Heartbeat message.
  31 data Message =
  32   Message {
  33     xml_file_id :: Int,
  34     heading :: String,
  35     time_stamp :: String }
  36   deriving (Eq, Show)
  37
  38
  39 -- | A (un)pickler that turns a Heartbeat XML file into a 'Message'
  40 --   and vice-versa.
  41 pickle_message :: PU Message
  42 pickle_message =
  43   xpElem "message" $
  44     xpWrap (from_tuple, to_tuple) $
  45     xpTriple (xpElem "XML_File_ID" xpInt)
  46              (xpElem "heading" xpText)
  47              (xpElem "time_stamp" xpText)
  48   where
  49     from_tuple = uncurryN Message
  50     to_tuple m = (xml_file_id m,
  51                   heading m,
  52                   time_stamp m)
  53
  54
  55 -- | Verify (and report) the received heartbeat. We return
  56 --   'ImportSkipped' because we want to indicate that we processed the
  57 --   file but there was nothing to import.
  58 --
  59 verify :: XmlTree -> IO ImportResult
  60 verify xml = do
  61   let root_element = unpickleDoc pickle_message xml
  62   return $ case root_element of
  63     Nothing -> ImportFailed "Could not unpickle document in import_generic."
  64     Just _  -> ImportSkipped "Heartbeat received. Thump."
  65
  66
  67 -- * Tasty Tests
  68 heartbeat_tests :: TestTree
  69 heartbeat_tests =
  70   testGroup
  71     "Heartbeat tests"
  72     [ test_pickle_of_unpickle_is_identity,
  73       test_unpickle_succeeds ]
  74
  75
  76 -- | Warning: succeess of this test does not mean that unpickling
  77 --   succeeded.
  78 --
  79 test_pickle_of_unpickle_is_identity :: TestTree
  80 test_pickle_of_unpickle_is_identity =
  81   testCase "pickle composed with unpickle is the identity" $ do
  82     let path = "test/xml/Heartbeat.xml"
  83     (expected :: [Message], actual) <- pickle_unpickle pickle_message path
  84     actual @?= expected
  85
  86
  87 -- | Make sure we can unpickle the sample file.
  88 --
  89 test_unpickle_succeeds :: TestTree
  90 test_unpickle_succeeds =
  91   testCase "unpickling succeeds" $ do
  92   let path = "test/xml/Heartbeat.xml"
  93   actual <- unpickleable path pickle_message
  94   let expected = True
  95   actual @?= expected