I have a simple data structure to test in smallcheck.

```
{-# LANGUAGE FlexibleInstances, MultiParamTypeClasses #-}
{-# LANGUAGE DeriveGeneric #-}
import Test.Tasty
import Test.Tasty.SmallCheck
import Test.SmallCheck.Series
import GHC.Generics
data T1 = T1 { p1 :: Int,
p2 :: Char,
p3 :: [Int]
} deriving (Eq, Show, Generic)
instance Monad m => Serial m T1
main :: IO ()
main = defaultMain tests
tests :: TestTree
tests = testGroup "Tests" [scProps]
scProps = testGroup "(checked by SmallCheck)"
[ testProperty "Test1" prop_test1
]
prop_test1 x = x == x
where types = (x :: T1)
```

When running the tests is there any general solution to set the `Depth`

parameter for the (individual) tests, or better yet, a fine grained solution to set the `Depth`

parameter for individual fields e.g. limit the depth of `p3`

to 2 to avoid the combinatorial explosion of the search space?

Many thanks in advance!

jules

info: A somewhat related question is here.

**EDIT:**

I took the solutions given in the accepted answer by Roman Cheplyaka and implemented them in a minimal working example (thanks, Roman):

```
{-# LANGUAGE FlexibleInstances, MultiParamTypeClasses #-}
import Test.Tasty
import Test.Tasty.Options
import Test.Tasty.SmallCheck
import Test.SmallCheck.Series
import Data.Functor
-- =============================================================================
main :: IO ()
main = defaultMain tests
-- =============================================================================
-- the data structure to be tested
data T1 = T1 { p1 :: Int,
p2 :: Char,
p3 :: Int,
p5 :: [Int]
} deriving (Show, Eq)
-- =============================================================================
-- some test-properties
prop_test1 x y = x == y
where types = (x :: T1, y :: T1)
prop_test2 x = x == x
where types = (x :: T1)
-- =============================================================================
-- how to change the depth of the search spaces?
{-| I Possibility: Command Line |-}
-- foo@bar$ runhaskell Test.hs --smallcheck-depth 2
-- -----------------------------------------------------------------------------
{-| II Possibility: |-}
-- normal:
-- tests :: TestTree
-- tests = testGroup "Tests" [scProps]
-- custom:
tests :: TestTree
tests = localOption d $ testGroup "Tests" [scProps]
where d = 3 :: SmallCheckDepth
scProps = testGroup "(checked by SmallCheck)"
[ testProperty "Test1" prop_test1,
testProperty "Test2" prop_test2
]
-- -----------------------------------------------------------------------------
{-| III Possibility: Adjust Depth when making the type instance of Serial |-}
-- normal:
-- instance (Monad m) => Serial m T1 where
-- series = T1 <$> series <~> series <~> series <~> series
-- custom:
instance (Monad m) => Serial m T1 where
series = localDepth (const 4) $ T1 <$> (localDepth (const 2) series) <~> series <~> series <~> (decDepth series)
-- (a few more examples):
-- instance (Monad m) => Serial m T1 where
-- series = decDepth $ T1 <$> series <~> series <~> series <~> (decDepth series )
-- instance (Monad m) => Serial m T1 where
-- series = localDepth (const 3) $ T1 <$> series <~> series <~> series <~> series
-- instance (Monad m) => Serial m T1 where
-- series = localDepth (const 4) $ T1 <$> series <~> series <~> series <~> (decDepth series)
```

`adjustOption`

,`localDepth`

without`const`

). In particular, using`localDepth . const`

in SmallCheck is rarely a good idea.