yesod-core: test for looping breadcrumbs

yesod-core/test/YesodCoreTest.hs

@@ -12,6 +12,7 @@ import YesodCoreTest.InternalRequest
 import YesodCoreTest.ErrorHandling
 import YesodCoreTest.Cache
 import YesodCoreTest.ParameterizedSite
+import YesodCoreTest.Breadcrumb
 import qualified YesodCoreTest.WaiSubsite as WaiSubsite
 import qualified YesodCoreTest.Redirect as Redirect
 import qualified YesodCoreTest.JsLoader as JsLoader
@@ -61,3 +62,4 @@ specs = do
       Ssl.sslOnlySpec
       Ssl.sameSiteSpec
       Csrf.csrfSpec
+      breadcrumbTest

yesod-core/test/YesodCoreTest/Breadcrumb.hs

@@ -0,0 +1,58 @@
+{-# LANGUAGE FlexibleInstances #-}
+{-# LANGUAGE MultiParamTypeClasses #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE QuasiQuotes #-}
+{-# LANGUAGE Rank2Types #-}
+{-# LANGUAGE TemplateHaskell #-}
+{-# LANGUAGE TypeFamilies #-}
+
+module YesodCoreTest.Breadcrumb
+  ( breadcrumbTest,
+  )
+where
+
+import qualified Data.ByteString.Lazy.Char8 as L8
+import Data.Text (Text)
+import Data.Typeable (Typeable)
+import Network.Wai
+import Network.Wai.Test
+import Test.Hspec
+import UnliftIO.IORef
+import Yesod.Core
+
+data A = A
+
+mkYesod
+  "A"
+  [parseRoutes|
+/    RootR GET
+/loop LoopR GET
+|]
+
+instance Yesod A
+
+instance YesodBreadcrumbs A where
+  breadcrumb r = case r of
+    RootR -> pure ("Root", Nothing)
+    LoopR -> pure ("Loop", Just LoopR) -- Purposefully a loop
+
+getRootR :: Handler Text
+getRootR = fst <$> breadcrumbs
+
+getLoopR :: Handler Text
+getLoopR = fst <$> breadcrumbs
+
+breadcrumbTest :: Spec
+breadcrumbTest =
+  describe "Test.Breadcrumb" $ do
+    it "can fetch the root which contains breadcrumbs" $
+      runner $ do
+        res <- request defaultRequest
+        assertStatus 200 res
+    it "gets a 500 for a route with a looping breadcrumb" $
+      runner $ do
+        res <- request defaultRequest {pathInfo = ["loop"]}
+        assertStatus 500 res
+
+runner :: Session () -> IO ()
+runner f = toWaiApp A >>= runSession f