Add some unit tests for Writers.Docbook

These are primarily aimed at testing the new treatment of line breaks,
but hopefully other tests can be added more easily now as features
and changes are implemented in the writer.

Adapted from Tests.Writers.HTML.tests.

tests/Tests/Writers/Docbook.hs

@@ -0,0 +1,52 @@
+{-# LANGUAGE OverloadedStrings #-}
+module Tests.Writers.Docbook (tests) where
+
+import Test.Framework
+import Text.Pandoc.Builder
+import Text.Pandoc
+import Tests.Helpers
+import Tests.Arbitrary()
+
+docbook :: (ToString a, ToPandoc a) => a -> String
+docbook = writeDocbook def{ writerWrapText = False } . toPandoc
+
+{-
+  "my test" =: X =?> Y
+
+is shorthand for
+
+  test docbook "my test" $ X =?> Y
+
+which is in turn shorthand for
+
+  test docbook "my test" (X,Y)
+-}
+
+infix 4 =:
+(=:) :: (ToString a, ToPandoc a)
+     => String -> (a, String) -> Test
+(=:) = test docbook
+
+lineblock :: Blocks
+lineblock = para ("some text" <> linebreak <>
+                  "and more lines" <> linebreak <>
+                  "and again")
+lineblock_out :: String
+lineblock_out =   "<literallayout>some text\n" ++
+                  "and more lines\n" ++
+                  "and again</literallayout>"
+
+tests :: [Test]
+tests = [ testGroup "line blocks"
+          [ "none"       =: para "This is a test"
+                              =?> "<para>\n  This is a test\n</para>"
+          , "basic"      =: lineblock
+                              =?> lineblock_out
+          , "blockquote" =: blockQuote lineblock
+                              =?> ("<blockquote>\n" ++ lineblock_out ++ "\n</blockquote>")
+          , "footnote"   =: para ("This is a test" <> note lineblock <> " of footnotes")
+                              =?> ("<para>\n  This is a test<footnote>\n" ++
+                                   lineblock_out ++
+                                   "\n  </footnote> of footnotes\n</para>")
+          ]
+        ]

tests/test-pandoc.hs

@@ -12,6 +12,7 @@ import qualified Tests.Readers.RST
 import qualified Tests.Writers.ConTeXt
 import qualified Tests.Writers.LaTeX
 import qualified Tests.Writers.HTML
+import qualified Tests.Writers.Docbook
 import qualified Tests.Writers.Native
 import qualified Tests.Writers.Markdown
 import qualified Tests.Shared
@@ -27,6 +28,7 @@ tests = [ testGroup "Old" Tests.Old.tests
           , testGroup "ConTeXt" Tests.Writers.ConTeXt.tests
           , testGroup "LaTeX" Tests.Writers.LaTeX.tests
           , testGroup "HTML" Tests.Writers.HTML.tests
+          , testGroup "Docbook" Tests.Writers.Docbook.tests
           , testGroup "Markdown" Tests.Writers.Markdown.tests
           ]
         , testGroup "Readers"