Data.SafeJSON.Test

This module contains some functions to use for testing SafeJSON and Migrate instances.

Consistency checks

It is advised to always run testConsistency (or testConsistency') for all your types that have a SafeJSON instance.

Note that any type that fails this test will also fail any safeFromJSON parsing!

Using TypeApplications

testConsistency :: forall a. SafeJSON a => Assertion

Useful in test suites. Will fail if anything in the chain of your types is inconsistent.

Example usage:

testConsistency @MyType

Using a Proxy argument

testConsistency' :: forall a. SafeJSON a => Proxy a -> Assertion

Useful in test suites. Will fail if anything in the chain of your types is inconsistent.

Unit tests

Migration tests

These tests can be used to verify the implemented migrate function acts as expected.

testMigration :: (Show a, Eq a, Migrate a) => MigrateFrom a -> a -> Assertion

Migration test. Mostly useful as regression test.

First argument is the older type which should turn into the second argument after migrating using migrate.

Just (migrate a) == parseMaybe (safeFromJSON . safeToJSON) a

testReverseMigration :: (Show a, Eq a, Migrate (Reverse a)) => MigrateFrom (Reverse a) -> a -> Assertion

Similar to testMigration, but using Migrate (Reverse a).

The first argument here is the newer type, which will be migrated back to the expected second argument (older type).

Just (unReverse $ migrate a) == parseMaybe (safeFromJSON . safeToJSON) a

Synonyms

(<=?) :: (Show a, Eq a, Migrate a) => MigrateFrom a -> a -> Assertion infix 1

Operator synonymous with testMigration

(>=?) :: (Show a, Eq a, Migrate (Reverse a)) => MigrateFrom (Reverse a) -> a -> Assertion infix 1

Operator synonymous with testReverseMigration

Round trip tests

These tests can be used to verify that round trips are consistent. Either directly (testRoundTrip), through a forward migration (migrateRoundTrip) or a reversed backward migration (migrateReverseRoundTrip).

testRoundTrip :: (Show a, Eq a, SafeJSON a) => a -> Assertion

Tests that the following holds:

Just a == parseMaybe (safeFromJSON . safeToJSON) a

migrateRoundTrip :: forall a. (Eq a, Show a, SafeJSON a, Migrate a) => MigrateFrom a -> Assertion

This test verifies that direct migration, and migration through encoding and decoding to the newer type, is equivalent.

migrateReverseRoundTrip :: forall a. (Eq a, Show a, SafeJSON a, Migrate (Reverse a)) => MigrateFrom (Reverse a) -> Assertion

Similar to migrateRoundTrip, but tests the migration from a newer type to the older type, in case of a Migrate (Reverse a) instance

Property tests

Useful if your types also have Arbitrary instances.

Constraint synonyms for readability

type TestMigrate a b = (Eq a, Show (MigrateFrom a), Arbitrary (MigrateFrom a), SafeJSON a, SafeJSON (MigrateFrom a), Migrate a, MigrateFrom a ~ b)

Constraints for migrating from a previous version

type TestReverseMigrate a b = (Eq a, Show (MigrateFrom (Reverse a)), Arbitrary (MigrateFrom (Reverse a)), SafeJSON a, Migrate (Reverse a), MigrateFrom (Reverse a) ~ b)

Constraints for migrating from a future version

Using TypeApplications

testRoundTripProp :: forall a. (Eq a, Show a, Arbitrary a, SafeJSON a) => String -> TestTree

Tests that the following holds for all a:

Just a == parseMaybe (safeFromJSON . safeToJSON) a

Example usage:

testRoundTripProp @MyType s

migrateRoundTripProp :: forall a b. TestMigrate a b => String -> TestTree

This test verifies that direct migration, and migration through encoding and decoding to the newer type, is equivalent for all a.

Just (migrate a) == parseMaybe (safeFromJSON . safeToJSON) a

Example usage:

migrateRoundTripProp @NewType @OldType s

migrateReverseRoundTripProp :: forall a b. TestReverseMigrate a b => String -> TestTree

Similar to migrateRoundTripProp, but tests the migration from a newer type to the older type, in case of a Migrate (Reverse a) instance.

Just (unReverse $ migrate a) == parseMaybe (safeFromJSON . safeToJSON) a

Example usage:

Please also note the reversing of the type applications.

migrateReverseRoundTripProp @OldType @NewType s

Using a Proxy argument

testRoundTripProp' :: forall a. (Eq a, Show a, Arbitrary a, SafeJSON a) => Proxy a -> String -> TestTree

Tests that the following holds for all a:

Just a == parseMaybe (safeFromJSON . safeToJSON) a

migrateRoundTripProp' :: forall a b. TestMigrate a b => Proxy (a, b) -> String -> TestTree

This test verifies that direct migration, and migration through encoding and decoding to the newer type, is equivalent for all a.

Just (migrate a) == parseMaybe (safeFromJSON . safeToJSON) a

migrateReverseRoundTripProp' :: forall a b. TestReverseMigrate a b => Proxy (a, b) -> String -> TestTree

Similar to 'migrateRoundTripProp, but tests the migration from a newer type to the older type, in case of a Migrate (Reverse a) instance.

Just (unReverse $ migrate a) == parseMaybe (safeFromJSON . safeToJSON) a

Re-export for convenience

data Proxy k t :: forall k. k -> *

A concrete, poly-kinded proxy type

Constructors

Proxy

Instances

Monad (Proxy *)

Methods

(>>=) :: Proxy * a -> (a -> Proxy * b) -> Proxy * b

(>>) :: Proxy * a -> Proxy * b -> Proxy * b

return :: a -> Proxy * a

fail :: String -> Proxy * a

Functor (Proxy *)

Methods

fmap :: (a -> b) -> Proxy * a -> Proxy * b

(<$) :: a -> Proxy * b -> Proxy * a

Applicative (Proxy *)

Methods

pure :: a -> Proxy * a

(<*>) :: Proxy * (a -> b) -> Proxy * a -> Proxy * b

(*>) :: Proxy * a -> Proxy * b -> Proxy * b

(<*) :: Proxy * a -> Proxy * b -> Proxy * a

Traversable (Proxy *)

Methods

traverse :: Applicative f => (a -> f b) -> Proxy * a -> f (Proxy * b)

sequenceA :: Applicative f => Proxy * (f a) -> f (Proxy * a)

mapM :: Monad m => (a -> m b) -> Proxy * a -> m (Proxy * b)

sequence :: Monad m => Proxy * (m a) -> m (Proxy * a)

Generic1 (Proxy *)

Associated Types

type Rep1 (Proxy * :: * -> *) :: * -> *

Methods

from1 :: Proxy * a -> Rep1 (Proxy *) a

to1 :: Rep1 (Proxy *) a -> Proxy * a

FromJSON1 (Proxy *)

Methods

liftParseJSON :: (Value -> Parser a) -> (Value -> Parser [a]) -> Value -> Parser (Proxy * a)

liftParseJSONList :: (Value -> Parser a) -> (Value -> Parser [a]) -> Value -> Parser [Proxy * a]

ToJSON1 (Proxy *)

Methods

liftToJSON :: (a -> Value) -> ([a] -> Value) -> Proxy * a -> Value

liftToJSONList :: (a -> Value) -> ([a] -> Value) -> [Proxy * a] -> Value

liftToEncoding :: (a -> Encoding) -> ([a] -> Encoding) -> Proxy * a -> Encoding

liftToEncodingList :: (a -> Encoding) -> ([a] -> Encoding) -> [Proxy * a] -> Encoding

Alternative (Proxy *)

Methods

empty :: Proxy * a

(<|>) :: Proxy * a -> Proxy * a -> Proxy * a

some :: Proxy * a -> Proxy * [a]

many :: Proxy * a -> Proxy * [a]

MonadPlus (Proxy *)

Methods

mzero :: Proxy * a

mplus :: Proxy * a -> Proxy * a -> Proxy * a

Hashable1 (Proxy *)

Methods

liftHashWithSalt :: (Int -> a -> Int) -> Int -> Proxy * a -> Int

Bounded (Proxy k s)

Methods

minBound :: Proxy k s

maxBound :: Proxy k s

Enum (Proxy k s)

Methods

succ :: Proxy k s -> Proxy k s

pred :: Proxy k s -> Proxy k s

toEnum :: Int -> Proxy k s

fromEnum :: Proxy k s -> Int

enumFrom :: Proxy k s -> [Proxy k s]

enumFromThen :: Proxy k s -> Proxy k s -> [Proxy k s]

enumFromTo :: Proxy k s -> Proxy k s -> [Proxy k s]

enumFromThenTo :: Proxy k s -> Proxy k s -> Proxy k s -> [Proxy k s]

Eq (Proxy k s)

Methods

(==) :: Proxy k s -> Proxy k s -> Bool

(/=) :: Proxy k s -> Proxy k s -> Bool

Ord (Proxy k s)

Methods

compare :: Proxy k s -> Proxy k s -> Ordering

(<) :: Proxy k s -> Proxy k s -> Bool

(<=) :: Proxy k s -> Proxy k s -> Bool

(>) :: Proxy k s -> Proxy k s -> Bool

(>=) :: Proxy k s -> Proxy k s -> Bool

max :: Proxy k s -> Proxy k s -> Proxy k s

min :: Proxy k s -> Proxy k s -> Proxy k s

Read (Proxy k s)

Methods

readsPrec :: Int -> ReadS (Proxy k s)

readList :: ReadS [Proxy k s]

readPrec :: ReadPrec (Proxy k s)

readListPrec :: ReadPrec [Proxy k s]

Show (Proxy k s)

Methods

showsPrec :: Int -> Proxy k s -> ShowS

show :: Proxy k s -> String

showList :: [Proxy k s] -> ShowS

Ix (Proxy k s)

Methods

range :: (Proxy k s, Proxy k s) -> [Proxy k s]

index :: (Proxy k s, Proxy k s) -> Proxy k s -> Int

unsafeIndex :: (Proxy k s, Proxy k s) -> Proxy k s -> Int

inRange :: (Proxy k s, Proxy k s) -> Proxy k s -> Bool

rangeSize :: (Proxy k s, Proxy k s) -> Int

unsafeRangeSize :: (Proxy k s, Proxy k s) -> Int

Generic (Proxy k t)

Associated Types

type Rep (Proxy k t) :: * -> *

Methods

from :: Proxy k t -> Rep (Proxy k t) x

to :: Rep (Proxy k t) x -> Proxy k t

Semigroup (Proxy k s)

Methods

(<>) :: Proxy k s -> Proxy k s -> Proxy k s

sconcat :: NonEmpty (Proxy k s) -> Proxy k s

stimes :: Integral b => b -> Proxy k s -> Proxy k s

Monoid (Proxy k s)

Methods

mempty :: Proxy k s

mappend :: Proxy k s -> Proxy k s -> Proxy k s

mconcat :: [Proxy k s] -> Proxy k s

Hashable (Proxy * a)

Methods

hashWithSalt :: Int -> Proxy * a -> Int

hash :: Proxy * a -> Int

FromJSON (Proxy k a)

Methods

parseJSON :: Value -> Parser (Proxy k a)

parseJSONList :: Value -> Parser [Proxy k a]

ToJSON (Proxy k a)

Methods

toJSON :: Proxy k a -> Value

toEncoding :: Proxy k a -> Encoding

toJSONList :: [Proxy k a] -> Value

toEncodingList :: [Proxy k a] -> Encoding

type Rep1 (Proxy *)

type Rep1 (Proxy *) = D1 (MetaData "Proxy" "Data.Proxy" "base" False) (C1 (MetaCons "Proxy" PrefixI False) U1)

type Rep (Proxy k t)

type Rep (Proxy k t) = D1 (MetaData "Proxy" "Data.Proxy" "base" False) (C1 (MetaCons "Proxy" PrefixI False) U1)