From c88b23e119e78bc268097f6dc1c837562d443d16 Mon Sep 17 00:00:00 2001
From: Pranay Sashank <pranaysashank@composewell.com>
Date: Thu, 4 Feb 2021 20:50:05 +0530
Subject: [PATCH] Add doctests test suite.

---
 .gitignore     |  1 +
 Setup.hs       |  4 ++--
 doctests.hs    | 14 ++++++++++++++
 streamly.cabal | 28 +++++++++++++++++++++++++++-
 4 files changed, 44 insertions(+), 3 deletions(-)
 create mode 100644 doctests.hs

diff --git a/.gitignore b/.gitignore
index 7bea6233..a0b039ee 100644
--- a/.gitignore
+++ b/.gitignore
@@ -14,3 +14,4 @@ cabal.project.local
 
 # Other
 .log
+_doctests/
diff --git a/Setup.hs b/Setup.hs
index 54f57d6f..26210cdb 100644
--- a/Setup.hs
+++ b/Setup.hs
@@ -1,6 +1,6 @@
 module Main (main) where
 
-import Distribution.Simple
+import Distribution.Extra.Doctest (defaultMainAutoconfWithDoctests)
 
 main :: IO ()
-main = defaultMainWithHooks autoconfUserHooks
+main = defaultMainAutoconfWithDoctests "doctests"
diff --git a/doctests.hs b/doctests.hs
new file mode 100644
index 00000000..300898f6
--- /dev/null
+++ b/doctests.hs
@@ -0,0 +1,14 @@
+module Main where
+
+import Build_doctests (flags, pkgs, module_sources)
+import Data.Foldable (traverse_)
+import System.Environment.Compat (unsetEnv)
+import Test.DocTest (doctest)
+
+main :: IO ()
+main = do
+    traverse_ putStrLn args
+    unsetEnv "GHC_ENVIRONMENT"
+    doctest args
+  where
+    args = flags ++ ["-outputdir=./_doctests/", "-fobject-code"] ++ pkgs ++ module_sources
diff --git a/streamly.cabal b/streamly.cabal
index 0ca26938..1f78601d 100644
--- a/streamly.cabal
+++ b/streamly.cabal
@@ -91,7 +91,7 @@ maintainer:          streamly@composewell.com
 copyright:           2017 Composewell Technologies
 category:            Control, Concurrency, Streaming, Reactivity
 stability:           Experimental
-build-type:          Configure
+build-type:          Custom
 
 extra-source-files:
     .circleci/config.yml
@@ -238,6 +238,16 @@ flag opt
   manual: True
   default: True
 
+flag doctests
+  description: Build doctests test suite
+  manual: True
+  default: False
+
+custom-setup
+ setup-depends:
+   base >= 4 && <5,
+   cabal-doctest >= 1 && <1.1
+
 -------------------------------------------------------------------------------
 -- Common stanzas
 -------------------------------------------------------------------------------
@@ -570,3 +580,19 @@ library
   -- tests fail
   if flag(dev) && flag(inspection)
     build-depends: inspection-and-dev-flags-cannot-be-used-together
+
+test-suite doctests
+  type:             exitcode-stdio-1.0
+  main-is:          doctests.hs
+  if flag(doctests)
+    build-depends:
+        base
+      , base-compat       >=0.10.5 && <0.12
+      , doctest           >=0.15   && <0.18
+      , streamly
+  else
+    buildable: False
+
+  ghc-options:      -Wall -threaded
+  hs-source-dirs:   .
+  default-language: Haskell2010