diff --git a/src/posts/0010-Haskell-Now/hspwg/app/Main.hs b/src/posts/0010-Haskell-Now/hspwg/app/Main.hs
index 4a932cc..188e0c8 100644
--- a/src/posts/0010-Haskell-Now/hspwg/app/Main.hs
+++ b/src/posts/0010-Haskell-Now/hspwg/app/Main.hs
@@ -4,9 +4,9 @@ module Main where
 
 import Protolude
 
-import qualified MyLib (genPassword)
+import qualified MyLib (someFunc)
 
 main :: IO ()
 main = do
-  pwd <- MyLib.genPassword
-  putText pwd
+  putText "Hello Haskell!"
+  MyLib.someFunc
diff --git a/src/posts/0010-Haskell-Now/hspwg/default.nix b/src/posts/0010-Haskell-Now/hspwg/default.nix
index 40f3806..295e5d4 100644
--- a/src/posts/0010-Haskell-Now/hspwg/default.nix
+++ b/src/posts/0010-Haskell-Now/hspwg/default.nix
@@ -18,7 +18,11 @@ in
     packages = p: [drv];
     # packages dependencies (by default haskellPackages)
     buildInputs = with haskellPackages;
-      [ hlint
+      [ apply-refact
+        hlint
+        stylish-haskell
+        hasktags
+        hoogle
         ghcid
         cabal-install
         cabal2nix
diff --git a/src/posts/0010-Haskell-Now/hspwg/hspwg.cabal b/src/posts/0010-Haskell-Now/hspwg/hspwg.cabal
index 8f43f4f..bf68667 100644
--- a/src/posts/0010-Haskell-Now/hspwg/hspwg.cabal
+++ b/src/posts/0010-Haskell-Now/hspwg/hspwg.cabal
@@ -55,4 +55,8 @@ test-suite hspwg-test
   type:                exitcode-stdio-1.0
   hs-source-dirs:      test
   main-is:             MyLibTest.hs
-  -- build-depends:       base ^>=4.12.0.0
+  build-depends:       protolude,
+                       tasty ^>= 1.2.0,
+                       tasty-hunit,
+                       tasty-smallcheck,
+                       tasty-quickcheck
diff --git a/src/posts/0010-Haskell-Now/hspwg/src/MyLib.hs b/src/posts/0010-Haskell-Now/hspwg/src/MyLib.hs
index 1555d91..25a96e8 100644
--- a/src/posts/0010-Haskell-Now/hspwg/src/MyLib.hs
+++ b/src/posts/0010-Haskell-Now/hspwg/src/MyLib.hs
@@ -1,15 +1,8 @@
 {-# LANGUAGE NoImplicitPrelude #-}
 {-# LANGUAGE OverloadedStrings #-}
-module MyLib (genPassword) where
+module MyLib (someFunc) where
 
 import           Protolude
 
-import           Data.Char     (chr,ord)
-import qualified System.Random as Random
-
-genPassword :: IO Text
-genPassword = do
-  let stdgen = Random.mkStdGen 0
-      numbers = take 10 (Random.randoms stdgen)
-      password = toS [ chr ( (n `mod` 27) + ord 'a') | n <- numbers ]
-  return password
+someFunc :: IO ()
+someFunc = putText "someFunc"
diff --git a/src/posts/0010-Haskell-Now/hspwg/test/MyLibTest.hs b/src/posts/0010-Haskell-Now/hspwg/test/MyLibTest.hs
index 3e2059e..fd9af6d 100644
--- a/src/posts/0010-Haskell-Now/hspwg/test/MyLibTest.hs
+++ b/src/posts/0010-Haskell-Now/hspwg/test/MyLibTest.hs
@@ -1,4 +1,50 @@
+{-# LANGUAGE NoImplicitPrelude #-}
+{-# LANGUAGE OverloadedStrings #-}
 module Main (main) where
 
+import Protolude
+
+import Test.Tasty
+import Test.Tasty.SmallCheck as SC
+import Test.Tasty.QuickCheck as QC
+import Test.Tasty.HUnit
+
 main :: IO ()
-main = putStrLn "Test suite not yet implemented."
+main = defaultMain tests
+
+tests :: TestTree
+tests = testGroup "Tests" [properties, unitTests]
+
+properties :: TestTree
+properties = testGroup "Properties" [scProps, qcProps]
+
+scProps = testGroup "(checked by SmallCheck)"
+  [ SC.testProperty "sort == sort . reverse" $
+      \list -> sort (list :: [Int]) == sort (reverse list)
+  , SC.testProperty "Fermat's little theorem" $
+      \x -> ((x :: Integer)^7 - x) `mod` 7 == 0
+  -- the following property does not hold
+  , SC.testProperty "Fermat's last theorem" $
+      \x y z n ->
+        (n :: Integer) >= 3 SC.==> x^n + y^n /= (z^n :: Integer)
+  ]
+
+qcProps = testGroup "(checked by QuickCheck)"
+  [ QC.testProperty "sort == sort . reverse" $
+      \list -> sort (list :: [Int]) == sort (reverse list)
+  , QC.testProperty "Fermat's little theorem" $
+      \x -> ((x :: Integer)^7 - x) `mod` 7 == 0
+  -- the following property does not hold
+  , QC.testProperty "Fermat's last theorem" $
+      \x y z n ->
+        (n :: Integer) >= 3 QC.==> x^n + y^n /= (z^n :: Integer)
+  ]
+
+unitTests = testGroup "Unit tests"
+  [ testCase "List comparison (different length)" $
+      [1, 2, 3] `compare` [1,2] @?= GT
+
+  -- the following test does not hold
+  , testCase "List comparison (same length)" $
+      [1, 2, 3] `compare` [1,2,2] @?= LT
+  ]