From ad4c204a87b2d75abf2702ea45864d11a053cb2f Mon Sep 17 00:00:00 2001
From: Simon Jakobi <simon.jakobi@gmail.com>
Date: Thu, 14 May 2026 20:57:02 +0200
Subject: [PATCH] Switch doctests to doctest-parallel (#290)

Fixes #290.

Assisted-By: Kimi K2.6
---
 cabal.project                                 |  1 +
 .../prettyprinter-ansi-terminal.cabal         |  3 +-
 .../Prettyprinter/Render/Terminal/Internal.hs |  1 +
 .../test/Doctest/Main.hs                      |  5 ++--
 prettyprinter/prettyprinter.cabal             |  3 +-
 prettyprinter/src/Prettyprinter/Internal.hs   | 13 ++-------
 .../src/Prettyprinter/Internal/Debug.hs       |  7 +++++
 .../src/Prettyprinter/Render/Text.hs          |  1 +
 .../Render/Tutorials/StackMachineTutorial.hs  | 29 ++++++++++---------
 .../Render/Tutorials/TreeRenderingTutorial.hs |  7 +++++
 .../Render/Util/SimpleDocTree.hs              |  1 +
 .../Prettyprinter/Render/Util/StackMachine.hs |  1 +
 .../src/Prettyprinter/Symbols/Ascii.hs        |  1 +
 prettyprinter/src/Prettyprinter/Util.hs       | 19 ++++++------
 prettyprinter/test/Doctest/Main.hs            |  9 ++----
 15 files changed, 58 insertions(+), 43 deletions(-)

diff --git a/cabal.project b/cabal.project
index 2c103018..9ce55649 100644
--- a/cabal.project
+++ b/cabal.project
@@ -8,3 +8,4 @@ packages: prettyprinter
         , prettyprinter-compat-annotated-wl-pprint
 tests: true
 benchmarks: true
+write-ghc-environment-files: always
diff --git a/prettyprinter-ansi-terminal/prettyprinter-ansi-terminal.cabal b/prettyprinter-ansi-terminal/prettyprinter-ansi-terminal.cabal
index c7e1f4ca..5242be3c 100644
--- a/prettyprinter-ansi-terminal/prettyprinter-ansi-terminal.cabal
+++ b/prettyprinter-ansi-terminal/prettyprinter-ansi-terminal.cabal
@@ -64,7 +64,8 @@ test-suite doctest
     main-is: Main.hs
     build-depends:
           base    >= 4.9 && < 5
-        , doctest >= 0.9
+        , doctest-parallel >= 0.1
+        , prettyprinter-ansi-terminal
     ghc-options: -Wall -threaded -rtsopts -with-rtsopts=-N
     default-language: Haskell2010
 
diff --git a/prettyprinter-ansi-terminal/src/Prettyprinter/Render/Terminal/Internal.hs b/prettyprinter-ansi-terminal/src/Prettyprinter/Render/Terminal/Internal.hs
index 16ed6dd2..165a03bf 100644
--- a/prettyprinter-ansi-terminal/src/Prettyprinter/Render/Terminal/Internal.hs
+++ b/prettyprinter-ansi-terminal/src/Prettyprinter/Render/Terminal/Internal.hs
@@ -63,6 +63,7 @@ import Data.Semigroup (Semigroup(..))
 -- >>> :set -XOverloadedStrings
 -- >>> import qualified Data.Text.Lazy.IO as TL
 -- >>> import qualified Data.Text.Lazy as TL
+-- >>> import Prettyprinter
 -- >>> import Prettyprinter.Render.Terminal
 
 
diff --git a/prettyprinter-ansi-terminal/test/Doctest/Main.hs b/prettyprinter-ansi-terminal/test/Doctest/Main.hs
index 563a5c63..12e27706 100644
--- a/prettyprinter-ansi-terminal/test/Doctest/Main.hs
+++ b/prettyprinter-ansi-terminal/test/Doctest/Main.hs
@@ -1,6 +1,7 @@
 module Main (main) where
 
-import Test.DocTest
+import Test.DocTest (mainFromCabal)
+import System.Environment (getArgs)
 
 main :: IO ()
-main = doctest [ "src" , "-Imisc"]
+main = mainFromCabal "prettyprinter-ansi-terminal" =<< getArgs
diff --git a/prettyprinter/prettyprinter.cabal b/prettyprinter/prettyprinter.cabal
index 5b6999d5..a3a7911b 100644
--- a/prettyprinter/prettyprinter.cabal
+++ b/prettyprinter/prettyprinter.cabal
@@ -20,7 +20,6 @@ source-repository head
     type: git
     location: https://github.com/quchen/prettyprinter
 
-
 library
     exposed-modules:
           Prettyprinter
@@ -123,7 +122,7 @@ test-suite doctest
     main-is: Main.hs
     build-depends:
           base       >= 4.9 && < 5
-        , doctest    >= 0.9
+        , doctest-parallel >= 0.1
         , prettyprinter
         , QuickCheck >= 2.5
     ghc-options: -Wall -threaded -rtsopts -with-rtsopts=-N
diff --git a/prettyprinter/src/Prettyprinter/Internal.hs b/prettyprinter/src/Prettyprinter/Internal.hs
index 6297c4fd..5b45ed93 100755
--- a/prettyprinter/src/Prettyprinter/Internal.hs
+++ b/prettyprinter/src/Prettyprinter/Internal.hs
@@ -1385,16 +1385,6 @@ spaces n
   | n == 1    = Char ' '
   | otherwise = Text n (textSpaces n)
 
--- $
--- prop> \(NonNegative n) -> length (show (spaces n)) == n
---
--- >>> case spaces 1 of Char ' ' -> True; _ -> False
--- True
---
--- >>> case spaces 0 of Empty -> True; _ -> False
--- True
---
--- prop> \(Positive n) -> case (spaces (-n)) of Empty -> True; _ -> False
 
 
 
@@ -2345,6 +2335,9 @@ textSpaces n = T.replicate n (T.singleton ' ')
 -- (Definitions for the doctests)
 --
 -- >>> :set -XOverloadedStrings
+-- >>> import Data.Functor.Identity
+-- >>> import Data.Text (Text)
+-- >>> import Data.Void (Void)
 -- >>> import Prettyprinter.Render.Text
 -- >>> import Prettyprinter.Symbols.Ascii
 -- >>> import Prettyprinter.Util as Util
diff --git a/prettyprinter/src/Prettyprinter/Internal/Debug.hs b/prettyprinter/src/Prettyprinter/Internal/Debug.hs
index ccff9cba..48fc7a86 100644
--- a/prettyprinter/src/Prettyprinter/Internal/Debug.hs
+++ b/prettyprinter/src/Prettyprinter/Internal/Debug.hs
@@ -28,6 +28,13 @@ import Data.Text (Text)
 import Prettyprinter.Internal (PageWidth, Doc)
 import qualified Prettyprinter.Internal as Doc
 
+-- $setup
+--
+-- (Definitions for the doctests)
+--
+-- >>> :set -XOverloadedStrings
+-- >>> import qualified Prettyprinter.Internal as Doc
+
 -- | A variant of 'Doc' for debugging.
 --
 -- Unlike in the 'Doc' type, the 'Column', 'WithPageWidth' and 'Nesting'
diff --git a/prettyprinter/src/Prettyprinter/Render/Text.hs b/prettyprinter/src/Prettyprinter/Render/Text.hs
index 0d6fbeaf..e97aef30 100644
--- a/prettyprinter/src/Prettyprinter/Render/Text.hs
+++ b/prettyprinter/src/Prettyprinter/Render/Text.hs
@@ -33,6 +33,7 @@ import Prettyprinter.Render.Util.Panic
 -- (Definitions for the doctests)
 --
 -- >>> :set -XOverloadedStrings
+-- >>> import Prettyprinter
 -- >>> import qualified Data.Text.IO as T
 -- >>> import qualified Data.Text.Lazy.IO as TL
 
diff --git a/prettyprinter/src/Prettyprinter/Render/Tutorials/StackMachineTutorial.hs b/prettyprinter/src/Prettyprinter/Render/Tutorials/StackMachineTutorial.hs
index b470b87b..c275efed 100644
--- a/prettyprinter/src/Prettyprinter/Render/Tutorials/StackMachineTutorial.hs
+++ b/prettyprinter/src/Prettyprinter/Render/Tutorials/StackMachineTutorial.hs
@@ -139,16 +139,19 @@ render doc
 --
 -- We can now render an example document using our definitions:
 --
--- >>> :set -XOverloadedStrings
--- >>> import qualified Data.Text.Lazy.IO as TL
--- >>> :{
--- >>> let go = TL.putStrLn . render . layoutPretty defaultLayoutOptions
--- >>> in go (vsep
--- >>>     [ headline "Example document"
--- >>>     , paragraph ("This is a" <+> color Red "paragraph" <> comma)
--- >>>     , paragraph ("and" <+> bold "this text is bold.")
--- >>>     ])
--- >>> :}
--- <h1>Example document</h1>
--- <p>This is a <span style="color: #f00">paragraph</span>,</p>
--- <p>and <strong>this text is bold.</strong></p>
+-- > :set -XOverloadedStrings
+-- > import qualified Data.Text.Lazy.IO as TL
+-- > :{
+-- > let go = TL.putStrLn . render . layoutPretty defaultLayoutOptions
+-- > in go (vsep
+-- >     [ headline "Example document"
+-- >     , paragraph ("This is a" <+> color Red "paragraph" <> comma)
+-- >     , paragraph ("and" <+> bold "this text is bold.")
+-- >     ])
+-- > :}
+--
+-- Result:
+--
+-- > <h1>Example document</h1>
+-- > <p>This is a <span style="color: #f00">paragraph</span>,</p>
+-- > <p>and <strong>this text is bold.</strong></p>
diff --git a/prettyprinter/src/Prettyprinter/Render/Tutorials/TreeRenderingTutorial.hs b/prettyprinter/src/Prettyprinter/Render/Tutorials/TreeRenderingTutorial.hs
index 5b81339a..022c7c54 100644
--- a/prettyprinter/src/Prettyprinter/Render/Tutorials/TreeRenderingTutorial.hs
+++ b/prettyprinter/src/Prettyprinter/Render/Tutorials/TreeRenderingTutorial.hs
@@ -25,6 +25,13 @@ import Prettyprinter.Render.Util.SimpleDocTree
 #if !(FOLDABLE_TRAVERSABLE_IN_PRELUDE)
 import Data.Foldable (foldMap)
 #endif
+
+-- $setup
+--
+-- (Definitions for the doctests)
+--
+-- >>> :set -XOverloadedStrings
+-- >>> import Prettyprinter
 #if !(SEMIGROUP_MONOID_SUPERCLASS)
 import Data.Semigroup
 #endif
diff --git a/prettyprinter/src/Prettyprinter/Render/Util/SimpleDocTree.hs b/prettyprinter/src/Prettyprinter/Render/Util/SimpleDocTree.hs
index 444d5506..cff767e0 100644
--- a/prettyprinter/src/Prettyprinter/Render/Util/SimpleDocTree.hs
+++ b/prettyprinter/src/Prettyprinter/Render/Util/SimpleDocTree.hs
@@ -43,6 +43,7 @@ import Data.Traversable (Traversable (..))
 --
 -- (Definitions for the doctests)
 --
+-- >>> :set -XOverloadedStrings
 -- >>> import Prettyprinter hiding ((<>))
 -- >>> import qualified Data.Text.IO as T
 
diff --git a/prettyprinter/src/Prettyprinter/Render/Util/StackMachine.hs b/prettyprinter/src/Prettyprinter/Render/Util/StackMachine.hs
index cb55f603..d58b1607 100644
--- a/prettyprinter/src/Prettyprinter/Render/Util/StackMachine.hs
+++ b/prettyprinter/src/Prettyprinter/Render/Util/StackMachine.hs
@@ -50,6 +50,7 @@ import Control.Applicative (liftA2)
 --
 -- (Definitions for the doctests)
 --
+-- >>> :set -XOverloadedStrings
 -- >>> import Prettyprinter hiding ((<>))
 -- >>> import qualified Data.Text.IO as T
 
diff --git a/prettyprinter/src/Prettyprinter/Symbols/Ascii.hs b/prettyprinter/src/Prettyprinter/Symbols/Ascii.hs
index 195f3aed..bb1568d3 100644
--- a/prettyprinter/src/Prettyprinter/Symbols/Ascii.hs
+++ b/prettyprinter/src/Prettyprinter/Symbols/Ascii.hs
@@ -150,5 +150,6 @@ pipe = Char '|'
 --
 -- >>> :set -XOverloadedStrings
 -- >>> import Data.Semigroup
+-- >>> import Prettyprinter
 -- >>> import Prettyprinter.Render.Text
 -- >>> import Prettyprinter.Util
diff --git a/prettyprinter/src/Prettyprinter/Util.hs b/prettyprinter/src/Prettyprinter/Util.hs
index 0dc16d39..035248ec 100644
--- a/prettyprinter/src/Prettyprinter/Util.hs
+++ b/prettyprinter/src/Prettyprinter/Util.hs
@@ -15,10 +15,19 @@ import Prettyprinter
 
 
 
+-- $setup
+--
+-- (Definitions for the doctests)
+--
+-- >>> :set -XOverloadedStrings
+-- >>> import Prelude hiding (words)
+
 -- | Split an input into word-sized 'Doc's.
 --
--- >>> putDoc (tupled (words "Lorem ipsum dolor"))
+-- @
+-- putDoc (tupled (words "Lorem ipsum dolor"))
 -- (Lorem, ipsum, dolor)
+-- @
 words :: Text -> [Doc ann]
 words = map pretty . T.words
 
@@ -55,11 +64,3 @@ putDocW :: Int -> Doc ann -> IO ()
 putDocW w doc = renderIO System.IO.stdout (layoutPretty layoutOptions (unAnnotate doc))
   where
     layoutOptions = LayoutOptions { layoutPageWidth = AvailablePerLine w 1 }
-
-
-
--- $setup
---
--- (Definitions for the doctests)
---
--- >>> :set -XOverloadedStrings
diff --git a/prettyprinter/test/Doctest/Main.hs b/prettyprinter/test/Doctest/Main.hs
index cf69622d..b598077f 100644
--- a/prettyprinter/test/Doctest/Main.hs
+++ b/prettyprinter/test/Doctest/Main.hs
@@ -1,10 +1,7 @@
 module Main (main) where
 
-import Test.DocTest
-
--- Silence -Wunused-packages:
-import Prettyprinter   ()
-import Test.QuickCheck ()
+import Test.DocTest (mainFromCabal)
+import System.Environment (getArgs)
 
 main :: IO ()
-main = doctest [ "src" , "-Imisc"]
+main = mainFromCabal "prettyprinter" =<< getArgs