Add generators and coverage for TxIn

lib/core/src/Cardano/Api/Gen.hs

@@ -0,0 +1,41 @@
+{-# LANGUAGE GADTs #-}
+{-# LANGUAGE NamedFieldPuns #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RankNTypes #-}
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE TupleSections #-}
+{-# LANGUAGE TypeApplications #-}
+
+module Cardano.Api.Gen
+  ( genTxIn
+  , genTxId
+  , genTxIndex
+  , genShelleyHash
+  ) where
+
+import Prelude
+
+import Cardano.Api hiding
+    ( txIns )
+import Test.QuickCheck
+    ( Gen, Large (..), arbitrary )
+
+import qualified Cardano.Binary as CBOR
+import qualified Cardano.Crypto.Hash as Crypto
+import qualified Shelley.Spec.Ledger.TxBody as Ledger
+    ( EraIndependentTxBody )
+
+genShelleyHash
+    :: Gen (Crypto.Hash Crypto.Blake2b_256 Ledger.EraIndependentTxBody)
+genShelleyHash = return . Crypto.castHash $ Crypto.hashWith CBOR.serialize' ()
+
+genTxIn :: Gen TxIn
+genTxIn = TxIn <$> genTxId <*> genTxIndex
+
+genTxId :: Gen TxId
+genTxId = TxId <$> genShelleyHash
+
+genTxIndex :: Gen TxIx
+genTxIndex = do
+    (Large (n :: Word)) <- arbitrary
+    pure $ TxIx n

lib/core/test/unit/Cardano/Api/GenSpec.hs

@@ -0,0 +1,62 @@
+{-# LANGUAGE GADTs #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE RankNTypes #-}
+{-# OPTIONS_GHC -fno-warn-orphans #-}
+
+module Cardano.Api.GenSpec (spec) where
+
+import Prelude
+
+import Cardano.Api
+    ( TxIn (..), TxIx (..) )
+import Cardano.Api.Gen
+import Data.Function
+    ( (&) )
+import Data.Word
+    ( Word32 )
+import Test.Hspec
+import Test.QuickCheck
+    ( Arbitrary
+    , Property
+    , arbitrary
+    , checkCoverage
+    , counterexample
+    , cover
+    , label
+    , property
+    )
+
+spec :: Spec
+spec =
+    describe "Cardano.Api.Gen" $
+        describe "Generator coverage" $ do
+            it "genTxIx" $
+                property genTxIxCoverage
+            it "genTxIn" $
+                property genTxInCoverage
+
+genTxIxCoverage :: TxIx -> Property
+genTxIxCoverage txIx = checkCoverage
+    $ cover 1 (txIx == TxIx 0)
+        "txIx is zero"
+    $ cover 2 (txIx >= veryLargeTxIx)
+        "txIx is very large"
+    $ cover 10 (txIx > TxIx 0 && txIx < veryLargeTxIx)
+        "txIx is between smallest and very large"
+    $ label "no txIx is negative" (txIx >= TxIx 0)
+      & counterexample "txIx was negative"
+    where
+        veryLargeTxIx :: TxIx
+        veryLargeTxIx = TxIx $ fromInteger $ toInteger (maxBound :: Word32)
+
+instance Arbitrary TxIx where
+    arbitrary = genTxIndex
+
+genTxInCoverage :: TxIn -> Property
+genTxInCoverage (TxIn _id ix) =
+    -- We don't provide any coverage for genShelleyHash, and so we don't provide
+    -- any coverage for txId either (as txId consists of a shelleyHash).
+    genTxIxCoverage ix
+
+instance Arbitrary TxIn where
+    arbitrary = genTxIn