Workaround for bug in pcre-light

Author: sol

src/JSONSchema/Validator/Draft4/String.hs

@@ -69,6 +69,8 @@ patternVal :: PatternValidator -> Text -> Maybe PatternInvalid
 patternVal a@(PatternValidator t) x =
     case RE.compileM (encodeUtf8 t) mempty of
         Left _   -> Just PatternNotRegex
-        Right re -> if x RE.=~ re
+        Right re -> if input RE.=~ re
                         then Nothing
                         else Just (PatternInvalid a x)
+  where
+    input = T.unpack x -- workaround for a bug in pcre-light

test/JSONSchema/Validator/Draft4/StringSpec.hs

@@ -15,3 +15,11 @@ spec = do
 
             it "rejects other strings" $ do
                 maxLengthVal (MaxLength 0) "foo" `shouldBe` Just (MaxLengthInvalid (MaxLength 0) "foo")
+
+    describe "patternVal" $ do
+        it "matches a substring" $ do
+            patternVal (PatternValidator "baz") "foo bar baz" `shouldBe` Nothing
+
+        context "with .*" $ do
+            it "matches the empty string (test for workaround for a bug in pcre-light)" $ do
+                patternVal (PatternValidator ".*") "" `shouldBe` Nothing