Powerpoint writer: Set default slidelevel correctly.

We had previously defaulted to slideLevel 2. Now we use the correct
behavior of defaulting to the highest level header followed by
content. We change an expected test result to match this behavior.

src/Text/Pandoc/Writers/Powerpoint.hs

@@ -47,6 +47,7 @@ import Text.Pandoc.Definition
 import qualified Text.Pandoc.UTF8 as UTF8
 import Text.Pandoc.Class (PandocMonad)
 import Text.Pandoc.Error (PandocError(..))
+import Text.Pandoc.Slides (getSlideLevel)
 import qualified Text.Pandoc.Class as P
 import Text.Pandoc.Options
 import Text.Pandoc.MIME
@@ -86,7 +87,7 @@ writePowerpoint opts (Pandoc meta blks) = do
                 , envOpts = opts
                 , envSlideLevel = case writerSlideLevel opts of
                                     Just n -> n
-                                    Nothing -> 2
+                                    Nothing -> getSlideLevel blks'
                 }
   runP env def $ do pres <- blocksToPresentation blks'
                     archv <- presentationToArchive pres

test/Tests/Writers/Powerpoint.hs

@@ -52,7 +52,7 @@ numSlideTests = testGroup "Number of slides in output"
     def
     (setTitle "My Title" $ doc $ para "foo")
   , testNumberOfSlides
-    "With h1 slide (using default slide-level)" 2
+    "With h1 slide (using default slide-level)" 1
     def
     (doc $ header 1 "Header" <> para "foo")
   , testNumberOfSlides