Expose "format" function in Sylish.hs (#259)

* Expose "format" function in Sylish.hs

It's going to be needed for the haskell-ide integration

* Update tests/Language/Haskell/StylishSpec.hs

Co-Authored-By: Jasper Van der Jeugt <jaspervdj@gmail.com>

* Remove empty line

Co-authored-by: Jasper Van der Jeugt <jaspervdj@gmail.com>

5 files changed, 70 insertions, 1 deletions

diff --git a/lib/Language/Haskell/Stylish.hs b/lib/Language/Haskell/Stylish.hs
index a40a7d2..4f6aa1f 100644
--- a/lib/Language/Haskell/Stylish.hs
+++ b/lib/Language/Haskell/Stylish.hs
@@ -16,6 +16,8 @@ module Language.Haskell.Stylish
       -- * Misc
     , module Language.Haskell.Stylish.Verbose
     , version
+    , format
+    , ConfigPath(..)
     , Lines
     , Step
     ) where
@@ -91,3 +93,13 @@ runStep exts mfp ls step =
 runSteps :: Extensions -> Maybe FilePath -> [Step] -> Lines
          -> Either String Lines
 runSteps exts mfp steps ls = foldM (runStep exts mfp) ls steps
+
+newtype ConfigPath = ConfigPath { unConfigPath :: FilePath }
+
+-- |Formats given contents optionally using the config provided as first param.
+-- The second file path is the location from which the contents were read.
+-- If provided, it's going to be printed out in the error message.
+format :: Maybe ConfigPath -> Maybe FilePath -> String -> IO (Either String Lines)
+format maybeConfigPath maybeFilePath contents = do
+  conf <- loadConfig (makeVerbose True) (fmap unConfigPath maybeConfigPath)
+  pure $ runSteps (configLanguageExtensions conf) maybeFilePath (configSteps conf) $ lines contents
diff --git a/stylish-haskell.cabal b/stylish-haskell.cabal
index de12c11..1f509a1 100644
--- a/stylish-haskell.cabal
+++ b/stylish-haskell.cabal
@@ -96,6 +96,7 @@ Test-suite stylish-haskell-tests
   Type:           exitcode-stdio-1.0
 
   Other-modules:
+    Language.Haskell.StylishSpec
     Language.Haskell.Stylish.Align
     Language.Haskell.Stylish.Block
     Language.Haskell.Stylish.Config
diff --git a/testdata/test-config.yaml b/testdata/test-config.yaml
new file mode 100644
index 0000000..b81fdc2
--- /dev/null
+++ b/testdata/test-config.yaml
@@ -0,0 +1,3 @@
+steps:
+  - records: {}
+indent: 2
diff --git a/tests/Language/Haskell/StylishSpec.hs b/tests/Language/Haskell/StylishSpec.hs
new file mode 100644
index 0000000..77a23b1
--- /dev/null
+++ b/tests/Language/Haskell/StylishSpec.hs
@@ -0,0 +1,51 @@
+module Language.Haskell.StylishSpec where
+
+--------------------------------------------------------------------------------
+import           Test.Framework                 (Test, testGroup)
+import           Test.Framework.Providers.HUnit (testCase)
+import           Test.HUnit                     (Assertion, (@?=))
+
+--------------------------------------------------------------------------------
+import           Language.Haskell.Stylish
+
+--------------------------------------------------------------------------------
+import           System.IO.Unsafe
+--------------------------------------------------------------------------------
+tests :: Test
+tests = testGroup "Language.Haskell.Stylish.Step.Tabs.Tests"
+    [ testCase "case 01" case01
+    , testCase "case 02" case02
+    , testCase "case 03" case03
+    ]
+
+--------------------------------------------------------------------------------
+case01 :: Assertion
+case01 = (@?=) result (unsafePerformIO $ format Nothing Nothing input)
+  where
+    input = "module Herp where\n data Foo = Bar | Baz"
+    result = Right [ "module Herp where"
+                   , "data Foo = Bar"
+                   , "    | Baz"
+                   ]
+
+case02 :: Assertion
+case02 = (@?=) result (unsafePerformIO $ format (Just configLocation) Nothing input)
+  where
+    configLocation = ConfigPath "testdata/test-config.yaml"
+    input = "module Herp where\n data Foo = Bar | Baz"
+    result = Right [ "module Herp where"
+                   , "data Foo = Bar"
+                   , "  | Baz"
+                   ]
+
+case03 :: Assertion
+case03 = do
+  actual <- format Nothing (Just fileLocation) input
+  actual @?= result
+  where
+    fileLocation = "directory/File.hs"
+    input = "module Herp"
+    result = Left $
+      "Language.Haskell.Stylish.Parse.parseModule: could not parse " <>
+      fileLocation <>
+      ": ParseFailed (SrcLoc \"<unknown>.hs\" 2 1) \"Parse error: EOF\""
diff --git a/tests/TestSuite.hs b/tests/TestSuite.hs
index a6f51ea..1138323 100644
--- a/tests/TestSuite.hs
+++ b/tests/TestSuite.hs
@@ -19,12 +19,14 @@ import qualified Language.Haskell.Stylish.Step.Squash.Tests
 import qualified Language.Haskell.Stylish.Step.Tabs.Tests
 import qualified Language.Haskell.Stylish.Step.TrailingWhitespace.Tests
 import qualified Language.Haskell.Stylish.Step.UnicodeSyntax.Tests
+import qualified Language.Haskell.StylishSpec
 
 
 --------------------------------------------------------------------------------
 main :: IO ()
 main = defaultMain
-    [ Language.Haskell.Stylish.Parse.Tests.tests
+    [ Language.Haskell.StylishSpec.tests
+    , Language.Haskell.Stylish.Parse.Tests.tests
     , Language.Haskell.Stylish.Config.Tests.tests
     , Language.Haskell.Stylish.Step.Data.Tests.tests
     , Language.Haskell.Stylish.Step.Imports.Tests.tests