diff --git a/megaparsec.cabal b/megaparsec.cabal
index f2f8921..821fdaf 100644
--- a/megaparsec.cabal
+++ b/megaparsec.cabal
@@ -144,10 +144,12 @@ test-suite tests
                     , Prim
                     , Util
   build-depends:      base           >= 4.6 && < 5
+                    , HUnit          >= 1.2 && < 1.4
                     , QuickCheck     >= 2.4 && < 3
                     , megaparsec     >= 4.3
                     , mtl            == 2.*
                     , test-framework >= 0.6 && < 1
+                    , test-framework-hunit       >= 0.3 && < 0.4
                     , test-framework-quickcheck2 >= 0.3 && < 0.4
                     , transformers   >= 0.4 && < 0.6
   default-extensions: CPP
diff --git a/tests/Prim.hs b/tests/Prim.hs
index 7ab6cd6..8c50360 100644
--- a/tests/Prim.hs
+++ b/tests/Prim.hs
@@ -47,8 +47,10 @@ import qualified Control.Monad.Writer.Lazy   as L
 import qualified Control.Monad.Writer.Strict as S
 
 import Test.Framework
+import Test.Framework.Providers.HUnit (testCase)
 import Test.Framework.Providers.QuickCheck2 (testProperty)
 import Test.QuickCheck hiding (label)
+import Test.HUnit (Assertion, (@?=))
 
 import Text.Megaparsec.Char
 import Text.Megaparsec.Error
@@ -96,9 +98,15 @@ tests = testGroup "Primitive parser combinators"
   , testProperty "combinator lookAhead"                prop_lookAhead_0
   , testProperty "combinator lookAhead hints"          prop_lookAhead_1
   , testProperty "combinator lookAhead messages"       prop_lookAhead_2
+  , testCase     "combinator lookAhead cerr"           case_lookAhead_3
   , testProperty "combinator notFollowedBy"       prop_notFollowedBy_0
   , testProperty "combinator notFollowedBy twice" prop_notFollowedBy_1
   , testProperty "combinator notFollowedBy eof"   prop_notFollowedBy_2
+  , testCase     "combinator notFollowedBy cerr"  case_notFollowedBy_3a
+  , testCase     "combinator notFollowedBy cerr"  case_notFollowedBy_3b
+  , testCase     "combinator notFollowedBy eerr"  case_notFollowedBy_4a
+  , testCase     "combinator notFollowedBy eerr"  case_notFollowedBy_4b
+  , testCase     "combinator eof return value"    case_eof
   , testProperty "combinator token"                    prop_token
   , testProperty "combinator tokens"                   prop_tokens
   , testProperty "parser state position"               prop_state_pos
@@ -203,7 +211,7 @@ prop_alternative_6 a b c = checkParser p r s
         r | c = posErr ab s $ [uneCh 'c', exEof] ++
                 [exCh 'a' | not a && not b] ++ [exCh 'b' | not b]
           | otherwise = Right s
-        s = abcRow' a b c
+        s = abcRow a b c
         ab = fromEnum a + fromEnum b
 
 -- Monad instance
@@ -363,7 +371,7 @@ prop_lookAhead_0 a b c = checkParser p r s
           | h == 'b' = posErr 0 s [uneCh 'b', exCh 'a']
           | h == 'c' = posErr 0 s [uneCh 'c', exSpec "label"]
           | otherwise  = posErr 1 s [uneCh (s !! 1), exEof]
-        s = abcRow' a b c
+        s = abcRow a b c
 
 prop_lookAhead_1 :: String -> Property
 prop_lookAhead_1 s = checkParser p r s
@@ -379,7 +387,13 @@ prop_lookAhead_2 a b c = checkParser p r s
         r | null s    = posErr 0 s [uneEof, exCh 'a']
           | a         = posErr 0 s [uneCh 'a', exCh 'b']
           | otherwise = posErr 0 s [uneCh (head s), exCh 'a']
-        s = abcRow' a b c
+        s = abcRow a b c
+
+case_lookAhead_3 :: Assertion
+case_lookAhead_3 = parse p "" s @?= posErr 1 s [msg emsg]
+  where p    = lookAhead (char 'a' *> fail emsg) :: Parser String
+        emsg = "ops!"
+        s    = "abc"
 
 prop_notFollowedBy_0 :: NonNegative Int -> NonNegative Int
                      -> NonNegative Int -> Property
@@ -410,8 +424,26 @@ prop_notFollowedBy_2 a' b' c' = checkParser p r s
           | otherwise      = posErr a s [uneEof, exCh 'a']
         s = abcRow a b c
 
--- We omit tests for 'eof' here because it's used virtually everywhere, it's
--- already thoroughly tested.
+case_notFollowedBy_3a :: Assertion
+case_notFollowedBy_3a = parse p "" "ab" @?= Right ()
+  where p = notFollowedBy (char 'a' *> char 'c')
+
+case_notFollowedBy_3b :: Assertion
+case_notFollowedBy_3b = parse p "" s @?= posErr 0 s [uneCh 'a', exCh 'c']
+  where p = notFollowedBy (char 'a' *> char 'd') <* char 'c'
+        s = "ab"
+
+case_notFollowedBy_4a :: Assertion
+case_notFollowedBy_4a = parse p "" "ab" @?= Right ()
+  where p = notFollowedBy (fail "ops!")
+
+case_notFollowedBy_4b :: Assertion
+case_notFollowedBy_4b = parse p "" s @?= posErr 0 s [uneCh 'a', exCh 'c']
+  where p = notFollowedBy (fail "ops!") <* char 'c'
+        s = "ab"
+
+case_eof :: Assertion
+case_eof = parse eof "" "" @?= Right ()
 
 prop_token :: String -> Property
 prop_token s = checkParser p r s
diff --git a/tests/Util.hs b/tests/Util.hs
index 5e99593..3f89328 100644
--- a/tests/Util.hs
+++ b/tests/Util.hs
@@ -34,7 +34,6 @@ module Util
   , (/=\)
   , (!=!)
   , abcRow
-  , abcRow'
   , posErr
   , uneCh
   , uneStr
@@ -132,15 +131,9 @@ n !=! m = simpleParse n "" === simpleParse m ""
 -- @a@ times, character “b” repeated @b@ times, and finally character “c”
 -- repeated @c@ times.
 
-abcRow :: Int -> Int -> Int -> String
-abcRow a b c = replicate a 'a' ++ replicate b 'b' ++ replicate c 'c'
-
--- | @abcRow' a b c@ generates string that includes character “a” if @a@ is
--- 'True', then optionally character “b” if @b@ is 'True', then character
--- “c” if @c@ is 'True'.
-
-abcRow' :: Bool -> Bool -> Bool -> String
-abcRow' a b c = abcRow (fromEnum a) (fromEnum b) (fromEnum c)
+abcRow :: Enum a => a -> a -> a -> String
+abcRow a b c = f a 'a' ++ f b 'b' ++ f c 'c'
+  where f x = replicate (fromEnum x)
 
 -- | @posErr pos s ms@ is an easy way to model result of parser that
 -- fails. @pos@ is how many tokens (characters) has been consumed before