feat: add pngmonod raster device to enum (#1688)

src/ocrmypdf/pluginspec.py

@@ -38,6 +38,7 @@ class GhostscriptRasterDevice(StrEnum):
     JPEGGRAY = 'jpeggray'
     JPEGCOLOR = 'jpeg'
     PNGMONO = 'pngmono'
+    PNGMONOD = 'pngmonod'
     PNGGRAY = 'pnggray'
     PNG256 = 'png256'
     PNG16M = 'png16m'

tests/test_pdfinfo.py

@@ -298,6 +298,14 @@ def test_ink_enum_is_picklable():
         assert pickle.loads(pickle.dumps(member)) is member
 
 
+def test_pngmonod_device_exists():
+    from ocrmypdf.pluginspec import GhostscriptRasterDevice
+
+    assert GhostscriptRasterDevice.PNGMONOD == 'pngmonod'
+    # PNGMONO retained for compatibility / explicit use
+    assert GhostscriptRasterDevice.PNGMONO == 'pngmono'
+
+
 def _ink_of_first_xobject(body: bytes):
     from ocrmypdf.pdfinfo._contentstream import _interpret_contents