From 9cb4ca3c771f9a67b1af19beb096bbfb8daba862 Mon Sep 17 00:00:00 2001
From: KtorZ <matthias.benkort@gmail.com>
Date: Wed, 6 Mar 2019 13:33:40 +0100
Subject: [PATCH] Review folder structure, file documentation and pragmas

- Review haddock documentation for Cardano.Wallet.Binary
- Remove unnecessart intermediary modules 'BinaryHelpers' and 'Binary/Helpers'
- Rename and organize test data to reflect source code organization
- Add license and copyright to source files' header
---
 cardano-wallet.cabal                          |  14 +-
 src/Cardano/Wallet/Binary.hs                  | 145 ++++++++++++------
 src/Cardano/Wallet/Binary/Helpers.hs          |  58 -------
 src/Cardano/Wallet/Binary/Packfile.hs         |   6 +-
 .../Binary/PackfileSpec-epoch-mainnet-104}    | Bin
 .../Wallet/BinarySpec-block-1}                | Bin
 .../Wallet/BinarySpec-block-2}                | Bin
 .../Wallet/BinarySpec-block-3}                | Bin
 .../Wallet/BinarySpec-block-header-1}         | Bin
 .../Cardano/Wallet/Binary/PackfileSpec.hs     |   4 +-
 test/unit/Cardano/Wallet/BinaryHelpers.hs     |  35 -----
 test/unit/Cardano/Wallet/BinarySpec.hs        | 101 ++++++++----
 12 files changed, 183 insertions(+), 180 deletions(-)
 delete mode 100644 src/Cardano/Wallet/Binary/Helpers.hs
 rename test/data/{epoch-mainnet-104 => Cardano/Wallet/Binary/PackfileSpec-epoch-mainnet-104} (100%)
 rename test/data/{block-1 => Cardano/Wallet/BinarySpec-block-1} (100%)
 rename test/data/{block-2 => Cardano/Wallet/BinarySpec-block-2} (100%)
 rename test/data/{block-3 => Cardano/Wallet/BinarySpec-block-3} (100%)
 rename test/data/{block-header-1 => Cardano/Wallet/BinarySpec-block-header-1} (100%)
 delete mode 100644 test/unit/Cardano/Wallet/BinaryHelpers.hs

diff --git a/cardano-wallet.cabal b/cardano-wallet.cabal
index 936f0657cb9..d7fb982396e 100644
--- a/cardano-wallet.cabal
+++ b/cardano-wallet.cabal
@@ -32,8 +32,6 @@ library
     ghc-options:         -Werror
   build-depends:
       base
-
-    -- Hackage Dependencies
     , binary
     , bytestring
     , cborg
@@ -45,9 +43,8 @@ library
       src
   exposed-modules:
       Cardano.Wallet.Binary
-    , Cardano.Wallet.Binary.Helpers
-    , Cardano.Wallet.Binary.Packfile
-    , Cardano.Wallet.Primitive
+      Cardano.Wallet.Binary.Packfile
+      Cardano.Wallet.Primitive
   other-modules:
       Paths_cardano_wallet
 
@@ -100,7 +97,6 @@ test-suite unit
   main-is:
       Main.hs
   other-modules:
-      Cardano.Wallet.BinaryHelpers
-    , Cardano.Wallet.BinarySpec
-    , Cardano.Wallet.Binary.PackfileSpec
-    , Cardano.Wallet.PrimitiveSpec
+      Cardano.Wallet.BinarySpec
+      Cardano.Wallet.Binary.PackfileSpec
+      Cardano.Wallet.PrimitiveSpec
diff --git a/src/Cardano/Wallet/Binary.hs b/src/Cardano/Wallet/Binary.hs
index 3aca9e133ed..bdd2fb61b5f 100644
--- a/src/Cardano/Wallet/Binary.hs
+++ b/src/Cardano/Wallet/Binary.hs
@@ -1,36 +1,28 @@
 {-# LANGUAGE DataKinds #-}
 {-# LANGUAGE RankNTypes #-}
-{-# OPTIONS_GHC -fno-warn-name-shadowing #-}
 
--- | These are (partial) CBOR decoders for blocks and block headers.
--- Note that we ignore most of the block's and header's content and only
--- retrieve the pieces of information relevant to us, wallet (we do assume a
--- trusted node and therefore, we needn't to care about verifying signatures and
--- blocks themselves).
+-- |
+-- Copyright: © 2018-2019 IOHK
+-- License: MIT
+--
+-- These are (partial) CBOR decoders for blocks and block headers. Note that we
+-- ignore most of the block's and header's content and only retrieve the pieces
+-- of information relevant to us, wallet (we do assume a trusted node and
+-- therefore, we needn't to care about verifying signatures and blocks
+-- themselves).
 
 module Cardano.Wallet.Binary
     ( decodeBlock
     , decodeBlockHeader
+
+    -- * Helpers
+    , inspectNextToken
+    , decodeList
+    , decodeListIndef
     ) where
 
-import qualified Codec.CBOR.Decoding as CBOR
-import qualified Codec.CBOR.Encoding as CBOR
-import qualified Codec.CBOR.Read as CBOR
-import qualified Codec.CBOR.Write as CBOR
-import Control.Monad
-    ( void )
-import qualified Data.ByteString.Lazy as BL
-import Data.Set
-    ( Set )
-import qualified Data.Set as Set
-import Data.Text
-    ( Text )
-import Data.Word
-    ( Word16, Word64 )
 import Prelude
 
-import Cardano.Wallet.Binary.Helpers
-    ( decodeList, decodeListIndef )
 import Cardano.Wallet.Primitive
     ( Address (..)
     , Block (..)
@@ -41,8 +33,22 @@ import Cardano.Wallet.Primitive
     , TxIn (..)
     , TxOut (..)
     )
+import Control.Monad
+    ( void )
+import qualified Data.ByteString.Lazy as BL
+import Data.Set
+    ( Set )
+import qualified Data.Set as Set
+import Data.Word
+    ( Word16, Word64 )
+import Debug.Trace
+    ( traceShow )
+
+import qualified Codec.CBOR.Decoding as CBOR
+import qualified Codec.CBOR.Encoding as CBOR
+import qualified Codec.CBOR.Read as CBOR
+import qualified Codec.CBOR.Write as CBOR
 
-{-# ANN module ("HLint: ignore Use <$>" :: Text) #-}
 
 decodeAddress :: CBOR.Decoder s Address
 decodeAddress = do
@@ -69,6 +75,7 @@ decodeAttributes = do
     _ <- CBOR.decodeMapLenCanonical -- Empty map of attributes
     return ((), CBOR.encodeMapLen 0)
 
+{-# ANN decodeBlock ("HLint: ignore Use <$>" :: String) #-}
 decodeBlock :: CBOR.Decoder s Block
 decodeBlock = do
     CBOR.decodeListLenCanonicalOf 2
@@ -76,7 +83,7 @@ decodeBlock = do
     case t of
         0 -> do -- Genesis Block
             _ <- CBOR.decodeListLenCanonicalOf 3
-            header <- decodeGenesisBlockHeader
+            h <- decodeGenesisBlockHeader
             -- NOTE
             -- We don't decode the body of genesis block because we don't need
             -- it. Genesis blocks occur at boundaries and contain various pieces
@@ -87,14 +94,14 @@ decodeBlock = do
             -- In theory, we should also:
             --
             -- _ <- decodeGenesisBlockBody
-            return $ Block header mempty
+            return $ Block h mempty
 
         1 -> do -- Main Block
             _ <- CBOR.decodeListLenCanonicalOf 3
-            header <- decodeMainBlockHeader
-            transactions <- decodeMainBlockBody
+            h <- decodeMainBlockHeader
+            txs <- decodeMainBlockBody
             -- _ <- decodeMainExtraData
-            return $ Block header transactions
+            return $ Block h txs
 
         _ -> do
             fail $ "decodeBlock: unknown block constructor: " <> show t
@@ -144,7 +151,7 @@ decodeGenesisBlockHeader = do
     _ <- decodeProtocolMagic
     previous <- decodePreviousBlockHeader
     _ <- decodeGenesisProof
-    epochIndex <- decodeGenesisConsensusData
+    epoch <- decodeGenesisConsensusData
     _ <- decodeGenesisExtraData
     -- NOTE
     -- Careful here, we do return a slot number of 0, which means that if we
@@ -152,14 +159,14 @@ decodeGenesisBlockHeader = do
     -- number of `0`. In practices, when parsing a full epoch, we can discard
     -- the genesis block entirely and we won't bother about modelling this
     -- extra complexity at the type-level. That's a bit dodgy though.
-    return $ BlockHeader epochIndex 0 previous
+    return $ BlockHeader epoch 0 previous
 
 decodeGenesisConsensusData :: CBOR.Decoder s Word64
 decodeGenesisConsensusData = do
     _ <- CBOR.decodeListLenCanonicalOf 2
-    epochIndex <- CBOR.decodeWord64
+    epoch <- CBOR.decodeWord64
     _ <- decodeDifficulty
-    return epochIndex
+    return epoch
 
 decodeGenesisExtraData :: CBOR.Decoder s ()
 decodeGenesisExtraData = do
@@ -205,9 +212,9 @@ decodeMainBlockHeader = do
     _ <- decodeProtocolMagic
     previous <- decodePreviousBlockHeader
     _ <- decodeMainProof
-    (epochIndex, slotNumber) <- decodeMainConsensusData
+    (epoch, slot) <- decodeMainConsensusData
     _ <- decodeMainExtraData
-    return $ BlockHeader epochIndex slotNumber previous
+    return $ BlockHeader epoch slot previous
 
 decodeMainConsensusData :: CBOR.Decoder s (Word64, Word16)
 decodeMainConsensusData = do
@@ -262,7 +269,7 @@ decodeProtocolMagic = do
     return ()
 
 decodeProxySignature
-    :: (forall s. CBOR.Decoder s ())
+    :: (forall x. CBOR.Decoder x ())
     -> CBOR.Decoder s ()
 decodeProxySignature decodeIndex = do
     _ <- CBOR.decodeListLenCanonicalOf 2
@@ -303,9 +310,9 @@ decodeSharesProof = do
 decodeSlotId :: CBOR.Decoder s (Word64, Word16)
 decodeSlotId = do
     _ <- CBOR.decodeListLenCanonicalOf 2
-    epochIndex <- CBOR.decodeWord64
-    slotNumber <- CBOR.decodeWord16
-    return (epochIndex, slotNumber)
+    epoch <- CBOR.decodeWord64
+    slot <- CBOR.decodeWord16
+    return (epoch, slot)
 
 decodeSoftwareVersion :: CBOR.Decoder s ()
 decodeSoftwareVersion = do
@@ -318,15 +325,16 @@ decodeTx :: CBOR.Decoder s Tx
 decodeTx = do
     _ <- CBOR.decodeListLenCanonicalOf 2
     _ <- CBOR.decodeListLenCanonicalOf 3
-    inputs <- decodeListIndef decodeTxIn
-    outputs <- decodeListIndef decodeTxOut
+    ins <- decodeListIndef decodeTxIn
+    outs <- decodeListIndef decodeTxOut
     _ <- decodeAttributes
     _ <- decodeList decodeTxWitness
-    return $ Tx inputs outputs
+    return $ Tx ins outs
 
 decodeTxPayload :: CBOR.Decoder s (Set Tx)
 decodeTxPayload = Set.fromList <$> decodeListIndef decodeTx
 
+{-# ANN decodeTxIn ("HLint: ignore Use <$>" :: String) #-}
 decodeTxIn :: CBOR.Decoder s TxIn
 decodeTxIn = do
     _ <- CBOR.decodeListLenCanonicalOf 2
@@ -343,16 +351,17 @@ decodeTxIn = do
     decodeTxIn' :: CBOR.Decoder s TxIn
     decodeTxIn' = do
         _ <- CBOR.decodeListLenCanonicalOf 2
-        txId <- CBOR.decodeBytes
+        tx <- CBOR.decodeBytes
         index <- CBOR.decodeWord32
-        return $ TxIn (Hash txId) index
+        return $ TxIn (Hash tx) index
 
+{-# ANN decodeTxOut ("HLint: ignore Use <$>" :: String) #-}
 decodeTxOut :: CBOR.Decoder s TxOut
 decodeTxOut = do
     _ <- CBOR.decodeListLenCanonicalOf 2
     addr <- decodeAddress
-    coin <- CBOR.decodeWord64
-    return $ TxOut addr (Coin coin)
+    c <- CBOR.decodeWord64
+    return $ TxOut addr (Coin c)
 
 decodeTxProof :: CBOR.Decoder s ()
 decodeTxProof = do
@@ -376,3 +385,49 @@ decodeUpdateProof :: CBOR.Decoder s ()
 decodeUpdateProof = do
     _ <- CBOR.decodeBytes -- Update Hash
     return ()
+
+
+-- * Helpers
+
+-- | Inspect the next token that has to be decoded and print it to the console
+-- as a trace. Useful for debugging Decoders.
+-- Example:
+--
+-- @
+--     myDecoder :: CBOR.Decoder s MyType
+--     myDecoder = do
+--         a <- CBOR.decodeWord64
+--         inspectNextToken
+--         [...]
+-- @
+inspectNextToken :: CBOR.Decoder s ()
+inspectNextToken =
+  CBOR.peekTokenType >>= flip traceShow (return ())
+
+-- | Decode an list of known length. Very similar to @decodeListIndef@.
+--
+-- @
+--     myDecoder :: CBOR.Decoder s [MyType]
+--     myDecoder = decodeList decodeOne
+--       where
+--         decodeOne :: CBOR.Decoder s MyType
+-- @
+decodeList :: forall s a . CBOR.Decoder s a -> CBOR.Decoder s [a]
+decodeList decodeOne = do
+    l <- CBOR.decodeListLenCanonical
+    CBOR.decodeSequenceLenN (flip (:)) [] reverse l decodeOne
+
+-- | Decode an arbitrary long list. CBOR introduce a "break" character to
+-- mark the end of the list, so we simply decode each item until we encounter
+-- a break character.
+--
+-- @
+--     myDecoder :: CBOR.Decoder s [MyType]
+--     myDecoder = decodeListIndef decodeOne
+--       where
+--         decodeOne :: CBOR.Decoder s MyType
+-- @
+decodeListIndef :: forall s a. CBOR.Decoder s a -> CBOR.Decoder s [a]
+decodeListIndef decodeOne = do
+    _ <- CBOR.decodeListLenIndef
+    CBOR.decodeSequenceLenIndef (flip (:)) [] reverse decodeOne
diff --git a/src/Cardano/Wallet/Binary/Helpers.hs b/src/Cardano/Wallet/Binary/Helpers.hs
deleted file mode 100644
index bfdcc1b9123..00000000000
--- a/src/Cardano/Wallet/Binary/Helpers.hs
+++ /dev/null
@@ -1,58 +0,0 @@
-{-# LANGUAGE RankNTypes #-}
-
--- | Some extra helpers on top of the CBOR library to help writing decoders.
-
-module Cardano.Wallet.Binary.Helpers
-    ( inspectNextToken
-    , decodeList
-    , decodeListIndef
-    ) where
-
-import qualified Codec.CBOR.Decoding as CBOR
-import Debug.Trace
-    ( traceShow )
-import Prelude
-
--- | Inspect the next token that has to be decoded and print it to the console
--- as a trace. Useful for debugging Decoders.
--- Example:
---
---     myDecoder :: CBOR.Decoder s MyType
---     myDecoder = do
---         a <- CBOR.decodeWord64
---         inspectNextToken
---         [...]
---
-inspectNextToken :: CBOR.Decoder s ()
-inspectNextToken =
-  CBOR.peekTokenType >>= flip traceShow (return ())
-
--- | Decode an list of known length. Very similar to @decodeListIndef@.
---
--- Example:
---
---     myDecoder :: CBOR.Decoder s [MyType]
---     myDecoder = decodeList decodeOne
---       where
---         decodeOne :: CBOR.Decoder s MyType
---
-decodeList :: forall s a . CBOR.Decoder s a -> CBOR.Decoder s [a]
-decodeList decodeOne = do
-    l <- CBOR.decodeListLenCanonical
-    CBOR.decodeSequenceLenN (flip (:)) [] reverse l decodeOne
-
--- | Decode an arbitrary long list. CBOR introduce a "break" character to
--- mark the end of the list, so we simply decode each item until we encounter
--- a break character.
---
--- Example:
---
---     myDecoder :: CBOR.Decoder s [MyType]
---     myDecoder = decodeListIndef decodeOne
---       where
---         decodeOne :: CBOR.Decoder s MyType
---
-decodeListIndef :: forall s a. CBOR.Decoder s a -> CBOR.Decoder s [a]
-decodeListIndef decodeOne = do
-    _ <- CBOR.decodeListLenIndef
-    CBOR.decodeSequenceLenIndef (flip (:)) [] reverse decodeOne
diff --git a/src/Cardano/Wallet/Binary/Packfile.hs b/src/Cardano/Wallet/Binary/Packfile.hs
index 909029eb165..fd3213852bf 100644
--- a/src/Cardano/Wallet/Binary/Packfile.hs
+++ b/src/Cardano/Wallet/Binary/Packfile.hs
@@ -1,4 +1,8 @@
--- | Decoder for the rust-cardano packfile format.
+-- |
+-- Copyright: © 2018-2019 IOHK
+-- License: MIT
+--
+-- Decoder for the rust-cardano packfile format.
 --
 -- A pack file is a collection of bytestring blobs.
 --
diff --git a/test/data/epoch-mainnet-104 b/test/data/Cardano/Wallet/Binary/PackfileSpec-epoch-mainnet-104
similarity index 100%
rename from test/data/epoch-mainnet-104
rename to test/data/Cardano/Wallet/Binary/PackfileSpec-epoch-mainnet-104
diff --git a/test/data/block-1 b/test/data/Cardano/Wallet/BinarySpec-block-1
similarity index 100%
rename from test/data/block-1
rename to test/data/Cardano/Wallet/BinarySpec-block-1
diff --git a/test/data/block-2 b/test/data/Cardano/Wallet/BinarySpec-block-2
similarity index 100%
rename from test/data/block-2
rename to test/data/Cardano/Wallet/BinarySpec-block-2
diff --git a/test/data/block-3 b/test/data/Cardano/Wallet/BinarySpec-block-3
similarity index 100%
rename from test/data/block-3
rename to test/data/Cardano/Wallet/BinarySpec-block-3
diff --git a/test/data/block-header-1 b/test/data/Cardano/Wallet/BinarySpec-block-header-1
similarity index 100%
rename from test/data/block-header-1
rename to test/data/Cardano/Wallet/BinarySpec-block-header-1
diff --git a/test/unit/Cardano/Wallet/Binary/PackfileSpec.hs b/test/unit/Cardano/Wallet/Binary/PackfileSpec.hs
index e66ef10bae4..30a880d1b8c 100644
--- a/test/unit/Cardano/Wallet/Binary/PackfileSpec.hs
+++ b/test/unit/Cardano/Wallet/Binary/PackfileSpec.hs
@@ -6,7 +6,7 @@ import Cardano.Wallet.Binary
     ( decodeBlock )
 import Cardano.Wallet.Binary.Packfile
     ( PackfileError (..), decodePackfile )
-import Cardano.Wallet.BinaryHelpers
+import Cardano.Wallet.BinarySpec
     ( unsafeDeserialiseFromBytes )
 import Cardano.Wallet.Primitive
     ( Block (..), BlockHeader (..) )
@@ -34,7 +34,7 @@ testTwoBlobs = packFileHeader
 -- Get this file from cardano-http-bridge with:
 -- wget -O test/data/epoch-mainnet-104 http://localhost:8080/mainnet/epoch/104
 testPackfile :: FilePath
-testPackfile = "test/data/epoch-mainnet-104"
+testPackfile = "test/data/Cardano/Wallet/Binary/PackfileSpec-epoch-mainnet-104"
 
 spec :: Spec
 spec = do
diff --git a/test/unit/Cardano/Wallet/BinaryHelpers.hs b/test/unit/Cardano/Wallet/BinaryHelpers.hs
deleted file mode 100644
index 461002b2d97..00000000000
--- a/test/unit/Cardano/Wallet/BinaryHelpers.hs
+++ /dev/null
@@ -1,35 +0,0 @@
-{-# LANGUAGE RankNTypes #-}
-
-module Cardano.Wallet.BinaryHelpers
-    ( hash16
-    , addr58
-    , unsafeDeserialiseFromBytes
-    ) where
-
-import Cardano.Wallet.Primitive
-import qualified Codec.CBOR.Decoding as CBOR
-import qualified Codec.CBOR.Read as CBOR
-import Data.ByteArray.Encoding
-    ( Base (Base16), convertFromBase )
-import Data.ByteString
-    ( ByteString )
-import Data.ByteString.Base58
-    ( bitcoinAlphabet, decodeBase58 )
-import qualified Data.ByteString.Lazy as BL
-import Prelude
-
--- | Make a Hash from a Base16 encoded string, without error handling.
-hash16 :: ByteString -> Hash a
-hash16 = either bomb Hash . convertFromBase Base16
-    where
-        bomb msg = error ("Could not decode test string: " <> msg)
-
--- | Make an Address from a Base58 encoded string, without error handling.
-addr58 :: ByteString -> Address
-addr58 = maybe (error "addr58: Could not decode") Address . decodeBase58 bitcoinAlphabet
-
--- | CBOR deserialise without error handling - handy for prototypes or testing.
-unsafeDeserialiseFromBytes :: (forall s. CBOR.Decoder s a) -> BL.ByteString -> a
-unsafeDeserialiseFromBytes decoder bytes =
-    either (\e -> error $ "unsafeDeserialiseFromBytes: " <> show e) snd $
-        CBOR.deserialiseFromBytes decoder bytes
diff --git a/test/unit/Cardano/Wallet/BinarySpec.hs b/test/unit/Cardano/Wallet/BinarySpec.hs
index 49cc6c2567a..1573cbaaec8 100644
--- a/test/unit/Cardano/Wallet/BinarySpec.hs
+++ b/test/unit/Cardano/Wallet/BinarySpec.hs
@@ -1,22 +1,67 @@
-{-# OPTIONS_GHC -fno-warn-orphans #-}
+{-# LANGUAGE RankNTypes #-}
 
-module Cardano.Wallet.BinarySpec (spec) where
+module Cardano.Wallet.BinarySpec
+    ( spec
+
+    -- * Helpers
+    , hash16
+    , addr58
+    , unsafeDeserialiseFromBytes
+    ) where
 
 import Prelude
 
-import qualified Data.Set as Set
+import Cardano.Wallet.Binary
+    ( decodeBlock, decodeBlockHeader )
+import Cardano.Wallet.Primitive
+    ( Address (..)
+    , Block (..)
+    , BlockHeader (..)
+    , Coin (..)
+    , Hash (..)
+    , Tx (..)
+    , TxIn (..)
+    , TxOut (..)
+    )
+import Data.ByteArray.Encoding
+    ( Base (Base16), convertFromBase )
+import Data.ByteString
+    ( ByteString )
+import Data.ByteString.Base58
+    ( bitcoinAlphabet, decodeBase58 )
+import Test.Hspec
+    ( Spec, describe, it, shouldBe )
 
+import qualified Codec.CBOR.Decoding as CBOR
+import qualified Codec.CBOR.Read as CBOR
+import qualified Data.ByteString.Lazy as BL
 import qualified Data.ByteString.Lazy.Char8 as L8
+import qualified Data.Set as Set
 
-import Test.Hspec
-    ( Spec, describe, it, shouldBe )
 
-import Cardano.Wallet.Binary
-    ( decodeBlock, decodeBlockHeader )
-import Cardano.Wallet.BinaryHelpers
-    ( addr58, hash16, unsafeDeserialiseFromBytes )
-import Cardano.Wallet.Primitive
-    ( Block (..), BlockHeader (..), Coin (..), Tx (..), TxIn (..), TxOut (..) )
+spec :: Spec
+spec = do
+    describe "Decoding blocks" $ do
+        it "should decode a block header" $ do
+            bs <- L8.readFile "test/data/Cardano/Wallet/BinarySpec-block-header-1"
+            let decoded = unsafeDeserialiseFromBytes decodeBlockHeader bs
+            decoded `shouldBe` blockHeader1
+
+        it "should decode a block without transactions" $ do
+            bs <- L8.readFile "test/data/Cardano/Wallet/BinarySpec-block-1"
+            let decoded = unsafeDeserialiseFromBytes decodeBlock bs
+            decoded `shouldBe` block1
+
+        it "should decode a block with transactions" $ do
+            bs <- L8.readFile "test/data/Cardano/Wallet/BinarySpec-block-2"
+            let decoded = unsafeDeserialiseFromBytes decodeBlock bs
+            decoded `shouldBe` block2
+
+        it "should decode a testnet block with a transaction" $ do
+            bs <- L8.readFile "test/data/Cardano/Wallet/BinarySpec-block-3"
+            let decoded = unsafeDeserialiseFromBytes decodeBlock bs
+            decoded `shouldBe` block3
+
 
 -- A mainnet block header
 blockHeader1 :: BlockHeader
@@ -98,25 +143,21 @@ block3 = Block
         ]
     }
 
-spec :: Spec
-spec = do
-    describe "Decoding blocks" $ do
-        it "should decode a block header" $ do
-            bs <- L8.readFile "test/data/block-header-1"
-            let decoded = unsafeDeserialiseFromBytes decodeBlockHeader bs
-            decoded `shouldBe` blockHeader1
 
-        it "should decode a block without transactions" $ do
-            bs <- L8.readFile "test/data/block-1"
-            let decoded = unsafeDeserialiseFromBytes decodeBlock bs
-            decoded `shouldBe` block1
+-- * Helpers
 
-        it "should decode a block with transactions" $ do
-            bs <- L8.readFile "test/data/block-2"
-            let decoded = unsafeDeserialiseFromBytes decodeBlock bs
-            decoded `shouldBe` block2
+-- | Make a Hash from a Base16 encoded string, without error handling.
+hash16 :: ByteString -> Hash a
+hash16 = either bomb Hash . convertFromBase Base16
+    where
+        bomb msg = error ("Could not decode test string: " <> msg)
 
-        it "should decode a testnet block with a transaction" $ do
-            bs <- L8.readFile "test/data/block-3"
-            let decoded = unsafeDeserialiseFromBytes decodeBlock bs
-            decoded `shouldBe` block3
+-- | Make an Address from a Base58 encoded string, without error handling.
+addr58 :: ByteString -> Address
+addr58 = maybe (error "addr58: Could not decode") Address . decodeBase58 bitcoinAlphabet
+
+-- | CBOR deserialise without error handling - handy for prototypes or testing.
+unsafeDeserialiseFromBytes :: (forall s. CBOR.Decoder s a) -> BL.ByteString -> a
+unsafeDeserialiseFromBytes decoder bytes =
+    either (\e -> error $ "unsafeDeserialiseFromBytes: " <> show e) snd $
+        CBOR.deserialiseFromBytes decoder bytes