From 5dc1802665122df97f1c94c71e1cded3a83b47b6 Mon Sep 17 00:00:00 2001
From: Richard Marko <srk@48.io>
Date: Wed, 15 Nov 2023 07:12:03 +0100
Subject: [PATCH] core: move Arbitrary instances near their types

This allows us to use them in remote serialization
round trip props.

Couple of them are not needed anymore (`NixLike` is the
default now) so whole `tests/Arbitrary` is gone.
---
 hnix-store-core/hnix-store-core.cabal         |  2 +-
 .../src/System/Nix/Internal/StorePath.hs      | 21 +++++++
 hnix-store-core/tests/Arbitrary.hs            | 58 -------------------
 hnix-store-core/tests/Hash.hs                 |  7 ++-
 hnix-store-core/tests/StorePath.hs            | 21 ++-----
 5 files changed, 34 insertions(+), 75 deletions(-)
 delete mode 100644 hnix-store-core/tests/Arbitrary.hs

diff --git a/hnix-store-core/hnix-store-core.cabal b/hnix-store-core/hnix-store-core.cabal
index 7dd5bd6..f21a66d 100644
--- a/hnix-store-core/hnix-store-core.cabal
+++ b/hnix-store-core/hnix-store-core.cabal
@@ -70,6 +70,7 @@ library
     , monad-control
     , mtl
     , nix-derivation >= 1.1.1 && <2
+    , QuickCheck
     , saltine
     , time
     , text
@@ -114,7 +115,6 @@ test-suite format-tests
   type: exitcode-stdio-1.0
   main-is: Driver.hs
   other-modules:
-    Arbitrary
     Derivation
     NarFormat
     Hash
diff --git a/hnix-store-core/src/System/Nix/Internal/StorePath.hs b/hnix-store-core/src/System/Nix/Internal/StorePath.hs
index 4ded6ad..e062eca 100644
--- a/hnix-store-core/src/System/Nix/Internal/StorePath.hs
+++ b/hnix-store-core/src/System/Nix/Internal/StorePath.hs
@@ -49,6 +49,8 @@ import           Crypto.Hash                    ( SHA256
                                                 , HashAlgorithm
                                                 )
 
+import Test.QuickCheck
+
 -- | A path in a Nix store.
 --
 -- From the Nix thesis: A store path is the full path of a store
@@ -72,6 +74,12 @@ instance Hashable StorePath where
   hashWithSalt s StorePath{..} =
     s `hashWithSalt` storePathHash `hashWithSalt` storePathName
 
+instance Arbitrary StorePath where
+  arbitrary =
+    liftA2 StorePath
+      arbitrary
+      arbitrary
+
 -- | The name portion of a Nix path.
 --
 -- 'unStorePathName' must only contain a-zA-Z0-9+._?=-, can't start
@@ -82,6 +90,13 @@ newtype StorePathName = StorePathName
     unStorePathName :: Text
   } deriving (Eq, Hashable, Ord, Show)
 
+instance Arbitrary StorePathName where
+  arbitrary = StorePathName . toText <$> ((:) <$> s1 <*> listOf sn)
+   where
+    alphanum = ['a' .. 'z'] <> ['A' .. 'Z'] <> ['0' .. '9']
+    s1       = elements $ alphanum <> "+-_?="
+    sn       = elements $ alphanum <> "+-._?="
+
 -- | The hash algorithm used for store path hashes.
 newtype StorePathHashPart = StorePathHashPart
   { -- | Extract the contents of the hash.
@@ -89,6 +104,9 @@ newtype StorePathHashPart = StorePathHashPart
   }
   deriving (Eq, Hashable, Ord, Show)
 
+instance Arbitrary StorePathHashPart where
+  arbitrary = mkStorePathHashPart @SHA256 . Bytes.Char8.pack <$> arbitrary
+
 mkStorePathHashPart
   :: forall hashAlgo
    . HashAlgorithm hashAlgo
@@ -167,6 +185,9 @@ newtype StoreDir = StoreDir {
     unStoreDir :: RawFilePath
   } deriving (Eq, Hashable, Ord, Show)
 
+instance Arbitrary StoreDir where
+  arbitrary = StoreDir . ("/" <>) . Bytes.Char8.pack <$> arbitrary
+
 -- | Render a 'StorePath' as a 'RawFilePath'.
 storePathToRawFilePath :: StoreDir -> StorePath -> RawFilePath
 storePathToRawFilePath storeDir StorePath{..} =
diff --git a/hnix-store-core/tests/Arbitrary.hs b/hnix-store-core/tests/Arbitrary.hs
deleted file mode 100644
index dcf40aa..0000000
--- a/hnix-store-core/tests/Arbitrary.hs
+++ /dev/null
@@ -1,58 +0,0 @@
-{-# language DataKinds            #-}
-{-# OPTIONS_GHC -Wno-orphans      #-}
-
-module Arbitrary where
-
-import qualified Data.ByteString.Char8         as BSC
-
-import           Test.Tasty.QuickCheck
-
-import           System.Nix.Internal.StorePath
-import           Crypto.Hash                        ( SHA256
-                                                    , Digest
-                                                    , hash
-                                                    )
-
-genSafeChar :: Gen Char
-genSafeChar = choose ('\1', '\127') -- ASCII without \NUL
-
-nonEmptyString :: Gen String
-nonEmptyString = listOf1 genSafeChar
-
-dir :: Gen String
-dir = ('/':) <$> listOf1 (elements $ '/':['a'..'z'])
-
-instance Arbitrary StorePathName where
-  arbitrary = StorePathName . toText <$> ((:) <$> s1 <*> listOf sn)
-   where
-    alphanum = ['a' .. 'z'] <> ['A' .. 'Z'] <> ['0' .. '9']
-    s1       = elements $ alphanum <> "+-_?="
-    sn       = elements $ alphanum <> "+-._?="
-
-instance Arbitrary StorePathHashPart where
-  arbitrary = mkStorePathHashPart @SHA256 . BSC.pack <$> arbitrary
-
-instance Arbitrary (Digest SHA256) where
-  arbitrary = hash . BSC.pack <$> arbitrary
-
-instance Arbitrary StoreDir where
-  arbitrary = StoreDir . ("/" <>) . BSC.pack <$> arbitrary
-
-newtype NixLike = NixLike {getNixLike :: StorePath}
- deriving (Eq, Ord, Show)
-
-instance Arbitrary NixLike where
-  arbitrary =
-    NixLike <$>
-      liftA2 StorePath
-        arbitraryTruncatedDigest
-        arbitrary
-   where
-    -- 160-bit hash, 20 bytes, 32 chars in base32
-    arbitraryTruncatedDigest = coerce . BSC.pack <$> replicateM 20 genSafeChar
-
-instance Arbitrary StorePath where
-  arbitrary =
-    liftA2 StorePath
-      arbitrary
-      arbitrary
diff --git a/hnix-store-core/tests/Hash.hs b/hnix-store-core/tests/Hash.hs
index 9a78342..866fa06 100644
--- a/hnix-store-core/tests/Hash.hs
+++ b/hnix-store-core/tests/Hash.hs
@@ -13,7 +13,6 @@ import           Test.Tasty.QuickCheck
 
 import           System.Nix.Hash
 import           System.Nix.StorePath
-import           Arbitrary
 import           System.Nix.Internal.Base
 import           Crypto.Hash                ( MD5
                                             , SHA1
@@ -49,6 +48,12 @@ spec_hash = do
 prop_nixBase32Roundtrip :: Property
 prop_nixBase32Roundtrip = forAllShrink nonEmptyString genericShrink $
   \x -> pure (encodeUtf8 x) === (B32.decode . B32.encode . encodeUtf8 $ x)
+  where
+    nonEmptyString :: Gen String
+    nonEmptyString = listOf1 genSafeChar
+
+    genSafeChar :: Gen Char
+    genSafeChar = choose ('\1', '\127') -- ASCII without \NUL
 
 -- | API variants
 prop_nixBase16Roundtrip :: StorePathHashPart -> Property
diff --git a/hnix-store-core/tests/StorePath.hs b/hnix-store-core/tests/StorePath.hs
index 2fd9d4e..e1977a2 100644
--- a/hnix-store-core/tests/StorePath.hs
+++ b/hnix-store-core/tests/StorePath.hs
@@ -9,22 +9,13 @@ import qualified Data.Attoparsec.Text
 import           Test.Tasty.QuickCheck
 
 import           System.Nix.StorePath
-import           Arbitrary
 
--- | Test that Nix(OS) like paths roundtrip
-prop_storePathRoundtrip :: StoreDir -> NixLike -> NixLike -> Property
-prop_storePathRoundtrip storeDir (_ :: NixLike) (NixLike x) =
+-- | Test @StorePath@ roundtrips using @parsePath@
+prop_storePathRoundtrip :: StoreDir -> StorePath -> Property
+prop_storePathRoundtrip storeDir x =
   parsePath storeDir (storePathToRawFilePath storeDir x) === pure x
 
--- | Test that any `StorePath` roundtrips
-prop_storePathRoundtrip' :: StoreDir -> StorePath -> Property
-prop_storePathRoundtrip' storeDir x =
-  parsePath storeDir (storePathToRawFilePath storeDir x) === pure x
-
-prop_storePathRoundtripParser :: StoreDir -> NixLike -> NixLike -> Property
-prop_storePathRoundtripParser storeDir (_ :: NixLike) (NixLike x) =
-  Data.Attoparsec.Text.parseOnly (pathParser storeDir) (storePathToText storeDir x) === pure x
-
-prop_storePathRoundtripParser' :: StoreDir -> StorePath -> Property
-prop_storePathRoundtripParser' storeDir x =
+-- | Test @StorePath@ roundtrips using @pathParser@
+prop_storePathRoundtripParser :: StoreDir -> StorePath -> Property
+prop_storePathRoundtripParser storeDir x =
   Data.Attoparsec.Text.parseOnly (pathParser storeDir) (storePathToText storeDir x) === pure x