Add a writer for Markua 0.10 (#7729)

Markua is a markdown variant used by Leanpub.
More information about Markua can be found at https://leanpub.com/markua/read.

Adds a new exported function `writeMarkua` from T.P.Writers.Markdown.
[API change]

Closes #1871.

Co-authored by Tim Wisotzki and Samuel Lemmenmeier.

2 files changed, 41 insertions, 0 deletions

diff --git a/test/Tests/Old.hs b/test/Tests/Old.hs
index e03d94e85..450449946 100644
--- a/test/Tests/Old.hs
+++ b/test/Tests/Old.hs
@@ -228,6 +228,7 @@ tests pandocPath =
     , test' "reader" ["-f", "ipynb", "-t", "html"]
       "ipynb/rank.ipynb" "ipynb/rank.out.html"
     ]
+  , testGroup "markua" [ testGroup "writer" $ writerTests' "markua"]
   ]
  where
     test'           = test pandocPath
diff --git a/test/Tests/Writers/Markua.hs b/test/Tests/Writers/Markua.hs
new file mode 100644
index 000000000..62239f3da
--- /dev/null
+++ b/test/Tests/Writers/Markua.hs
@@ -0,0 +1,40 @@
+{-# LANGUAGE OverloadedStrings #-}
+module Tests.Writers.Markua (tests) where
+
+import Test.Tasty
+import Tests.Helpers
+import Text.Pandoc
+import Text.Pandoc.Arbitrary ()
+import Text.Pandoc.Builder
+
+{-
+  "my test" =: X =?> Y
+
+is shorthand for
+
+  test html "my test" $ X =?> Y
+
+which is in turn shorthand for
+
+  test html "my test" (X,Y)
+-}
+
+infix 4 =:
+(=:) :: (ToString a, ToPandoc a)
+     => String -> (a, String) -> TestTree
+(=:) = test (purely (writeMarkua def) . toPandoc)
+
+tests :: [TestTree]
+tests = [ testGroup "simple blurb/aside"
+          ["blurb"          =: divWith ("",["blurb"],[]) (bulletList [para "blurb content"])
+                           =?> "B> * blurb content"
+          ,"aside"          =: divWith ("",["aside"],[]) (bulletList [para "aside list"])
+                           =?> "A> * aside list"
+          ]
+         ,testGroup "multiclass blurb/aside"
+          ["blurb"          =: divWith ("",["blurb", "otherclass"],[]) (bulletList [para "blurb content"])
+                           =?> "B> * blurb content"
+          ,"aside"          =: divWith ("",["otherclass", "aside"],[]) (bulletList [para "aside list"])
+                           =?> "A> * aside list"
+          ]
+         ]