test: add test for formatting

INSTALL.md

@@ -55,8 +55,8 @@ cabal install spex spex-demo-petstore
 
 If you don't use Nix, then the easiest way to get the right Haskell
 dependencies is to first install
-[`ghcup`](https://www.haskell.org/ghcup/install/), the
-[Haskell](https://www.haskell.org/) installer, and then issue:
+[`ghcup`](https://www.haskell.org/ghcup/install/), the Haskell installer, and
+then issue:
 
 ```bash
 git clone https://github.com/spex-lang/spex.git

README.md

@@ -329,7 +329,7 @@ more details about how to use them.
 
 ## Installation
 
-See [`INSTALL.md`](INSTALL.md).
+See [`INSTALL.md`](INSTALL.md) for installation instructions.
 
 ## Usage
 

spex.cabal

@@ -123,5 +123,4 @@ test-suite test
     , spex
     , tasty
     , tasty-golden
-    , tasty-hunit
     , temporary

src/Spex/CommandLine/Option.hs

@@ -25,7 +25,7 @@ data Options = Options
   , nonInteractive :: Bool
   }
 
--- XXX: renmae veryVerbose to trace?
+-- XXX: rename veryVerbose to trace?
 data Logging = Quiet Bool | Verbose Bool | VeryVerbose Bool
 
 data Command
@@ -48,7 +48,10 @@ data VerifyOptions = VerifyOptions
   }
 
 data FormatOptions = FormatOptions
-  {specFilePath :: FilePath}
+  { specFilePath :: FilePath
+  , output :: Maybe FilePath
+  -- , inPlace :: Inplace ; data InPlace = NotInplace | Inplace | InplaceWithBackup Suffix
+  }
 
 data CheckOptions = CheckOptions
   {specFilePath :: FilePath}
@@ -212,7 +215,17 @@ parser =
         )
 
     format :: Parser FormatOptions
-    format = FormatOptions <$> specFile
+    format =
+      FormatOptions
+        <$> specFile
+        <*> optional
+          ( strOption
+              ( long "output"
+                  <> short 'o'
+                  <> metavar "FILE"
+                  <> help "Output file path for the formatted specification"
+              )
+          )
 
     check :: Parser CheckOptions
     check = CheckOptions <$> specFile

src/Spex/LibMain.hs

@@ -5,7 +5,7 @@ import Data.ByteString qualified as BS
 import Data.ByteString.Lazy qualified as LBS
 import GHC.IO.Encoding (setLocaleEncoding)
 import System.Exit
-import System.IO (utf8)
+import System.IO (IOMode (WriteMode), utf8, withFile)
 
 import Spex.CommandLine.Option
 import Spex.Lexer
@@ -83,7 +83,9 @@ formatApp :: FormatOptions -> App ()
 formatApp opts = do
   bs <- liftIO (try (BS.readFile opts.specFilePath)) <?> ReadSpecFileError
   spec <- pure (runParser specP bs) <?> ParserError
-  liftIO (putSpec spec)
+  case opts.output of
+    Nothing -> liftIO (putSpec spec)
+    Just fp -> liftIO $ withFile fp WriteMode $ \h -> hPutSpec h spec
 
 checkApp :: CheckOptions -> App ()
 checkApp opts = do

src/Spex/PrettyPrinter.hs

@@ -9,7 +9,8 @@ import Data.Map (Map)
 import Data.Map qualified as Map
 import Data.String
 import Prettyprinter
-import Prettyprinter.Util
+import Prettyprinter.Render.Text
+import System.IO
 
 import Spex.Syntax
 
@@ -90,4 +91,7 @@ prettyBS :: (Coercible a ByteString) => a -> Doc x
 prettyBS = fromString . BS8.unpack . coerce
 
 putSpec :: Spec -> IO ()
-putSpec = putDocW 72 . prettySpec
+putSpec = hPutSpec stdout
+
+hPutSpec :: Handle -> Spec -> IO ()
+hPutSpec h = hPutDoc h . prettySpec

test/Main.hs

@@ -18,15 +18,23 @@ tests :: FilePath -> TestTree
 tests tmpDir =
   testGroup
     "Golden"
-    [ withPetstore
-        0
-        ( test
-            [ "verify"
-            , "example/petstore-basic.spex"
-            , "--seed"
-            , "2503963955766725184"
+    [ testGroup
+        "Verify"
+        ( zipWith
+            withPetstore
+            [ test
+                [ "verify"
+                , "example/petstore-basic.spex"
+                , "--seed"
+                , "2503963955766725184"
+                ]
             ]
+            [0 ..] -- Used to compute the ports used by the tests.
         )
+    , testGroup
+        "Format"
+        [ testOutput ["format", "example/petstore-bad-formatting.spex"]
+        ]
     ]
   where
     test :: [String] -> TestTree
@@ -41,8 +49,20 @@ tests tmpDir =
             logFile
             (testMain ("--non-interactive" : "--log-file" : logFile : args))
 
-    withPetstore :: Int -> TestTree -> TestTree
-    withPetstore i tt =
+    testOutput :: [String] -> TestTree
+    testOutput args =
+      let testName = intercalate " " args
+          outName = replace '/' '-' (intercalate "_" args)
+          outFile = tmpDir </> outName <.> "txt"
+      in  goldenVsFileDiff
+            testName
+            (\ref new -> ["diff", "-u", ref, new])
+            ("test" </> "golden" </> outName <.> "golden")
+            outFile
+            (testMain ("--non-interactive" : args ++ ["--output", outFile]))
+
+    withPetstore :: TestTree -> Int -> TestTree
+    withPetstore tt i =
       withResource
         (forkIO (Petstore.libMain (8080 + i)))
         killThread

test/golden/format_example-petstore-bad-formatting.spex.golden

@@ -0,0 +1,4 @@
+component PetStore where
+
+addPet : POST /pet Pet 
+getPet : GET /pet/{petId : Int} -> Pet