diff --git a/lab4/test/Spec.hs b/lab4/test/Spec.hs
index 360ec28..ab58924 100644
--- a/lab4/test/Spec.hs
+++ b/lab4/test/Spec.hs
@@ -1,5 +1,5 @@
 import Test.QuickCheck
-import Lib (isCongruent)
+import Lib
 
 propCongruentDifference :: Int -> Int -> Int -> Property
 propCongruentDifference a b m =
@@ -13,8 +13,25 @@ propCongruentEqualNumbers :: Int -> Int -> Property
 propCongruentEqualNumbers a m =
   m /= 0 ==> isCongruent a a m == True
 
+
+propFilterByPredicateSatisfiesPredicate :: Fun Int Bool -> [Int] -> Bool
+propFilterByPredicateSatisfiesPredicate (Fun _ predicate) xs =
+  all predicate (filterByPredicate predicate xs)
+
+propFilterByPredicateLength :: Fun Int Bool -> [Int] -> Bool
+propFilterByPredicateLength (Fun _ predicate) xs =
+  length (filterByPredicate predicate xs) <= length xs
+
+propFilterByPredicateAlwaysTrue :: [Int] -> Bool
+propFilterByPredicateAlwaysTrue xs =
+  filterByPredicate (\_ -> True) xs == xs
+
 main :: IO ()
 main = do
   quickCheck propCongruentDifference
   quickCheck propCongruentSymmetric
   quickCheck propCongruentEqualNumbers
+
+  quickCheck propFilterByPredicateSatisfiesPredicate
+  quickCheck propFilterByPredicateLength
+  quickCheck propFilterByPredicateAlwaysTrue