Add tests for ToValidFunctionName

servant-js/servant-js.cabal

@@ -93,4 +93,5 @@ test-suite spec
                    , servant
                    , servant-js
                    , text
+                   , QuickCheck
   default-language:  Haskell2010

servant-js/src/Servant/JS/Internal.hs

@@ -1,5 +1,4 @@
 {-# LANGUAGE OverloadedStrings #-}
-{-# LANGUAGE ViewPatterns #-}
 
 module Servant.JS.Internal
   ( JavaScriptGenerator
@@ -116,12 +115,11 @@ toValidFunctionName t =
       setFirstChar x `T.cons` T.filter remainder xs
     Nothing -> "_"
   where
-    setFirstChar c = if firstChar c then c else '_'
-    firstChar c = prefixOK c || Set.member c firstLetterOK
-    remainder c = prefixOK c || Set.member c remainderOK
-    prefixOK c = c `elem` ['$','_']
+    setFirstChar c = if Set.member c firstLetterOK then c else '_'
+    remainder c = Set.member c remainderOK
     firstLetterOK = (filterBmpChars $ mconcat
-                      [ Set.lowercaseLetter
+                      [ Set.fromDistinctAscList "$_"
+                      , Set.lowercaseLetter
                       , Set.uppercaseLetter
                       , Set.titlecaseLetter
                       , Set.modifierLetter

servant-js/test/Servant/JSSpec.hs

@@ -15,10 +15,14 @@ import           Data.Monoid.Compat           ((<>))
 import           Data.Proxy
 import           Data.Text                    (Text)
 import qualified Data.Text                    as T
+import           Language.ECMAScript3.Lexer   (identifier)
 import           Language.ECMAScript3.Parser  (program, parse)
 import           Prelude                      ()
 import           Prelude.Compat
 import           Test.Hspec  hiding (shouldContain, shouldNotContain)
+import           Test.QuickCheck                            (Arbitrary (..),
+                                                             choose, listOf,
+                                                             property)
 
 import           Servant.API.Internal.Test.ComprehensiveAPI
 import           Servant.API.ContentTypes
@@ -97,6 +101,7 @@ spec = describe "Servant.JQuery" $ do
     angularSpec    Angular
     axiosSpec
     --angularSpec    AngularCustom
+    internalSpec
 
 shouldContain :: Text -> Text -> Expectation
 a `shouldContain` b  = shouldSatisfy a (T.isInfixOf b)
@@ -152,6 +157,21 @@ angularSpec test = describe specLabel $ do
         ngOpts = NG.defAngularOptions { NG.serviceName = testName }
         genJS req = NG.angularService ngOpts req
 
+instance Arbitrary T.Text where
+    -- Our arbitrary instance is generating only ASCII, since language-ecmascript lexer
+    -- is currently (October 2016) still a bit naïve
+    arbitrary = fmap T.pack $ listOf $ choose (minBound, '\127')
+    shrink xs = T.pack <$> shrink (T.unpack xs)
+
+internalSpec :: Spec
+internalSpec = describe "Internal" $ do
+    it "should generate only valid javascript identifiers for any ASCII route" $ do
+        let parseIdentifier = fmap (T.pack . filter (< '\65536')) . parse identifier ""
+        property $ \x -> let valid = toValidFunctionName x in
+                         Right valid == parseIdentifier valid
+    it "should generate a valid javascript identifier when supplied with hyphens, unicode whitespace, non-bmp unicode" $ do
+        toValidFunctionName "a_--a\66352b\6158c\65075" `shouldBe` "a_abc\65075"
+
 generateJSSpec :: TestNames -> (AjaxReq -> Text) -> Spec
 generateJSSpec n gen = describe specLabel $ do
     let parseFromText = parse program ""