Fix test_outputtype_none on Windows and cleanup docs

docs/cookbook.rst

@@ -104,6 +104,9 @@ This produces a file named "output.pdf" and a companion text file named
     because of options like ``--skip-big`` or ``--tesseract-timeout``, those pages
     will not be in the sidecar.
 
+    If you don't want to generate the output PDF, use ``--output-type=none`` to
+    avoid generating one. Set the output filename to ``-`` (i.e. redirect to stdout).
+
     To extract all text from a PDF, whether generated from OCR or otherwise,
     use a program like Poppler's ``pdftotext`` or ``pdfgrep``.
 

src/ocrmypdf/_validation.py

@@ -78,11 +78,11 @@ def check_options_output(options):
             "`--pdf-renderer auto` (the default) to avoid this issue."
         )
 
-    if options.output_type == 'none' and options.output_file != os.devnull:
+    if options.output_type == 'none' and options.output_file not in (os.devnull, '-'):
         raise BadArgsError(
-            "Since you specified `--pdf-renderer none`, the output file "
+            "Since you specified `--output-type none`, the output file "
             f"{options.output_file} cannot be produced. Set the output file to "
-            f"{os.devnull} to suppress this message."
+            f"`-` to suppress this message."
         )
 
     lossless_reconstruction = False

tests/test_main.py

@@ -916,9 +916,9 @@ def test_outputtype_none_bad_setup(resources, outpdf):
 
 
 def test_outputtype_none(resources, outtxt):
-    p, _out, err = run_ocrmypdf(
+    p, out, err = run_ocrmypdf(
         resources / 'trivial.pdf',
-        os.devnull,
+        '-',
         '--output-type=none',
         '--sidecar',
         outtxt,
@@ -926,4 +926,3 @@ def test_outputtype_none(resources, outtxt):
         'tests/plugins/tesseract_noop.py',
     )
     assert p.returncode == ExitCode.ok
-    assert outtxt.exists()