diff --git a/geval.cabal b/geval.cabal
index 5424adf..e86b594 100644
--- a/geval.cabal
+++ b/geval.cabal
@@ -17,6 +17,11 @@ library
   hs-source-dirs:      src
   exposed-modules:     Lib
   build-depends:       base >= 4.7 && < 5
+                     , conduit
+                     , conduit-combinators
+                     , conduit-extra
+                     , resourcet
+                     , text
   default-language:    Haskell2010
 
 executable geval-exe
@@ -33,6 +38,7 @@ test-suite geval-test
   main-is:             Spec.hs
   build-depends:       base
                      , geval
+                     , hspec
   ghc-options:         -threaded -rtsopts -with-rtsopts=-N
   default-language:    Haskell2010
 
diff --git a/src/Lib.hs b/src/Lib.hs
index 0e6faba..ff65835 100644
--- a/src/Lib.hs
+++ b/src/Lib.hs
@@ -2,6 +2,24 @@ module Lib
     ( geval
     ) where
 
+import Data.Conduit
+import Data.Conduit.Combinators as CC
+import qualified Data.Conduit.Binary as CB
+import qualified Data.Conduit.Text as CT
+import Control.Monad.Trans.Resource
+import qualified Data.Conduit.List as CL
+import Data.Text
+import Data.Text.Read as TR
+
 geval :: String -> String -> IO (Double)
 geval expectedFilePath outFilePath = do
-  return $ 3.14
+  runResourceT $
+    CB.sourceFile expectedFilePath
+    $$ CT.decode CT.utf8
+    =$= CT.lines
+    =$= CL.map TR.double
+    =$= CC.map getValue
+    =$ CC.sum
+
+getValue :: Either String (Double, Text) -> Double
+getValue (Right (x, _)) = x
diff --git a/test/Spec.hs b/test/Spec.hs
index cd4753f..812d517 100644
--- a/test/Spec.hs
+++ b/test/Spec.hs
@@ -1,2 +1,9 @@
+import Test.Hspec
+
+import Lib
+
 main :: IO ()
-main = putStrLn "Test suite not yet implemented"
+main = hspec $ do
+  describe "mean square error" $ do
+    it "simple test" $ do
+      geval "test/mse-simple/mse-simple/test-A/expected.tsv" "test/mse-simple/mse-simple-solution/test-A/out.tsv" `shouldReturn` 1.118033988749