Add spec for serverLayout

Author: nbacquey

servant-server/test/Servant/Server/RouterSpec.hs

@@ -27,6 +27,7 @@ spec :: Spec
 spec = describe "Servant.Server.Internal.Router" $ do
   routerSpec
   distributivitySpec
+  serverLayoutSpec
 
 routerSpec :: Spec
 routerSpec = do
@@ -101,12 +102,28 @@ distributivitySpec =
     it "properly handles mixing static paths at different levels" $ do
       level `shouldHaveSameStructureAs` levelRef
 
+serverLayoutSpec :: Spec
+serverLayoutSpec =
+  describe "serverLayout" $ do
+    it "correctly represents the example API" $ do
+      exampleLayout `shouldHaveLayout` expectedExampleLayout
+    it "aggregates capture hints when different" $ do
+      dynamic `shouldHaveLayout` expectedDynamicLayout
+    it "nubs capture hints when equal" $ do
+      dynamicSameType `shouldHaveLayout` expectedDynamicSameTypeLayout
+
 shouldHaveSameStructureAs ::
   (HasServer api1 '[], HasServer api2 '[]) => Proxy api1 -> Proxy api2 -> Expectation
 shouldHaveSameStructureAs p1 p2 =
   unless (sameStructure (makeTrivialRouter p1) (makeTrivialRouter p2)) $
     expectationFailure ("expected:\n" ++ unpack (layout p2) ++ "\nbut got:\n" ++ unpack (layout p1))
 
+shouldHaveLayout ::
+  (HasServer api '[]) => Proxy api -> Text -> Expectation
+shouldHaveLayout p l =
+  unless (routerLayout (makeTrivialRouter p) == l) $
+    expectationFailure ("expected:\n" ++ unpack l ++ "\nbut got:\n" ++ unpack (layout p))
+
 makeTrivialRouter :: (HasServer layout '[]) => Proxy layout -> Router ()
 makeTrivialRouter p =
   route p EmptyContext (emptyDelayed (FailFatal err501))
@@ -342,3 +359,74 @@ level = Proxy
 
 levelRef :: Proxy LevelRef
 levelRef = Proxy
+
+-- The example API for the 'layout' function.
+-- Should get factorized by the 'choice' smart constructor.
+type ExampleLayout =
+       "a" :> "d" :> Get '[JSON] NoContent
+  :<|> "b" :> Capture "x" Int :> Get '[JSON] Bool
+  :<|> "c" :> Put '[JSON] Bool
+  :<|> "a" :> "e" :> Get '[JSON] Int
+  :<|> "b" :> Capture "x" Int :> Put '[JSON] Bool
+  :<|> Raw
+
+exampleLayout :: Proxy ExampleLayout
+exampleLayout = Proxy
+
+-- The expected representation of the example API layout
+--
+expectedExampleLayout :: Text
+expectedExampleLayout =
+  "/\n\
+  \├─ a/\n\
+  \│  ├─ d/\n\
+  \│  │  └─•\n\
+  \│  └─ e/\n\
+  \│     └─•\n\
+  \├─ b/\n\
+  \│  └─ <x::CaptureSingle>/\n\
+  \│     ├─•\n\
+  \│     ┆\n\
+  \│     └─•\n\
+  \├─ c/\n\
+  \│  └─•\n\
+  \┆\n\
+  \└─ <raw>\n"
+
+-- The expected representation of the Dynamic API layout.
+--
+expectedDynamicLayout :: Text
+expectedDynamicLayout =
+  "/\n\
+  \└─ a/\n\
+  \   └─ <foo::CaptureSingle|bar::CaptureSingle|baz::CaptureSingle>/\n\
+  \      ├─ b/\n\
+  \      │  └─•\n\
+  \      ├─ c/\n\
+  \      │  └─•\n\
+  \      └─ d/\n\
+  \         └─•\n"
+
+-- The same Dynamic API as above, except that the captured
+-- values have the same hints
+type DynamicSameType =
+       "a" :> Capture "foo" Int :> "b" :> End
+  :<|> "a" :> Capture "foo" Int :> "c" :> End
+  :<|> "a" :> Capture "foo" Int :> "d" :> End
+
+dynamicSameType :: Proxy DynamicSameType
+dynamicSameType = Proxy
+
+-- The expected representation of the DynamicSameType API layout.
+--
+expectedDynamicSameTypeLayout :: Text
+expectedDynamicSameTypeLayout =
+  "/\n\
+  \└─ a/\n\
+  \   └─ <foo::CaptureSingle>/\n\
+  \      ├─ b/\n\
+  \      │  └─•\n\
+  \      ├─ c/\n\
+  \      │  └─•\n\
+  \      └─ d/\n\
+  \         └─•\n"