diff --git a/Main.hs b/Main.hs
index 2fbdd98..107c76b 100644
--- a/Main.hs
+++ b/Main.hs
@@ -1,46 +1,7 @@
 module Main where
 
-import Data.Aeson (FromJSON, parseJSON, withObject, withText, (.:), decode)
-
-data Program = Program { programFns :: [Function] }
-    deriving (Show)
-
-data Function = Function {
-        functionName :: String,
-        returnType :: Maybe Type,
-        functionArgs :: [FunctionArg]
-    } deriving (Show)
-
-data Type = Int | Bool
-    deriving (Show)
-
-data FunctionArg = FunctionArg {
-        argName :: String,
-        argType :: Type
-    } deriving (Show)
-
-instance FromJSON Program  where
-    parseJSON = withObject "Program" $ \v -> Program
-        <$> v .: "functions"
-
-instance FromJSON Function where
-    parseJSON = withObject "Function" $ \v -> Function
-        <$> v .: "name"
-        <*> v .: "type"
-        <*> v .: "args"
-
-instance FromJSON FunctionArg where
-    parseJSON = withObject "FunctionArg" $ \v -> FunctionArg
-        <$> v .: "name"
-        <*> v .: "type"
-
-instance FromJSON Type where
-    parseJSON = withText "Type" $ \v ->
-        case v of
-             "int" -> return Int
-             "bool" -> return Bool
-             _ -> fail "wrong type"
+import Bril
 
 main :: IO ()
 main = do
-    putStrLn $ show (decode "int" :: Maybe Type)
+    putStrLn $ "Hello World!"
diff --git a/eoc.cabal b/eoc.cabal
index 4beb66d..19ab010 100644
--- a/eoc.cabal
+++ b/eoc.cabal
@@ -1,4 +1,4 @@
-cabal-version:       >=1.10
+cabal-version:       2.0
 -- Initial package description 'eoc.cabal' generated by 'cabal init'.  For
 -- further documentation, see http://haskell.org/cabal/users-guide/
 
@@ -16,13 +16,35 @@ maintainer:          enrico.lumetti@gmail.com
 build-type:          Simple
 extra-source-files:  README.md
 
+library eoc-lib
+    exposed-modules: Eoc, Bril
+    hs-source-dirs: lib
+    build-depends:
+        base >=4.13 && <4.18,
+        aeson >= 2.2
+    default-language: Haskell2010
+  default-extensions: DeriveGeneric, OverloadedStrings
+
 executable eoc
   main-is:             Main.hs
   -- other-modules:
   -- other-extensions:
   build-depends:
-      base >=4.13 && <4.14,
-      aeson >= 2.2
+      base >=4.13 && <4.18,
+      eoc-lib
   -- hs-source-dirs:
   default-language:    Haskell2010
   default-extensions: DeriveGeneric, OverloadedStrings
+
+test-suite tests
+    type: exitcode-stdio-1.0
+    main-is: Main.hs
+    build-depends:
+        base >=4.13 && <4.18,
+        HUnit >=1.6,
+        eoc-lib,
+        aeson >= 2.2
+    hs-source-dirs: tests
+    default-language: Haskell2010
+    default-extensions: DeriveGeneric, OverloadedStrings
+
diff --git a/lib/Bril.hs b/lib/Bril.hs
new file mode 100644
index 0000000..ecdb43a
--- /dev/null
+++ b/lib/Bril.hs
@@ -0,0 +1,47 @@
+module Bril (
+    Function (..), Type (..), FunctionArg (..), Program (..), Int, Bool,
+    )where
+
+import Data.Aeson (FromJSON, parseJSON, withObject, withText, (.:), decode, Value)
+
+
+data Program = Program { programFns :: [Function] }
+    deriving (Show, Eq)
+
+data Function = Function {
+        functionName :: String,
+        returnType :: Maybe Type,
+        functionArgs :: [FunctionArg]
+    } deriving (Show, Eq)
+
+data Type = Int | Bool
+    deriving (Show, Eq)
+
+data FunctionArg = FunctionArg {
+        argName :: String,
+        argType :: Type
+    } deriving (Show, Eq)
+
+instance FromJSON Program  where
+    parseJSON = withObject "Program" $ \v -> Program
+        <$> v .: "functions"
+
+instance FromJSON Function where
+    parseJSON = withObject "Function" $ \v -> Function
+        <$> v .: "name"
+        <*> v .: "type"
+        <*> v .: "args"
+
+instance FromJSON FunctionArg where
+    parseJSON = withObject "FunctionArg" $ \v -> FunctionArg
+        <$> v .: "name"
+        <*> v .: "type"
+
+instance FromJSON Type where
+    parseJSON = withText "Type" $ \v ->
+        case v of
+             "int" -> return Int
+             "bool" -> return Bool
+             _ -> fail "wrong type"
+
+parseBrilJSON text = (decode text :: Maybe Program)
diff --git a/lib/Eoc.hs b/lib/Eoc.hs
new file mode 100644
index 0000000..8a511eb
--- /dev/null
+++ b/lib/Eoc.hs
@@ -0,0 +1,2 @@
+module Eoc where
+
diff --git a/tests/Main.hs b/tests/Main.hs
new file mode 100644
index 0000000..bdddf87
--- /dev/null
+++ b/tests/Main.hs
@@ -0,0 +1,20 @@
+module Main where
+
+import qualified Bril as B
+import Data.Aeson (decode)
+import Data.Maybe
+
+import Test.HUnit
+import qualified System.Exit as Exit
+ 
+test1 :: Test
+test1 = TestCase
+        (assertEqual "?" (decode "\"int\"" :: Maybe B.Type) (Just B.Int))
+ 
+tests :: Test
+tests = TestList [TestLabel "test1" test1]
+ 
+main :: IO ()
+main = do
+    result <- runTestTT tests
+    if failures result > 0 then Exit.exitFailure else Exit.exitSuccess