fix: detect multi-word options sections in usage

The regex used to detect options: sections in the usage: section was
different to the one acutally used to parse sections, and it failed to
find options sections with extra words, like "Advanced Options:".

This also adds a test for the "options (case-insensitive) was found in
usage." message, which we need because currently the only test that
triggers it is test_issue_71... which does so by mistake.

docopt/__init__.py

@@ -887,10 +887,9 @@ def docopt(
         )
     if len(usage_sections) > 1:
         raise DocoptLanguageError('More than one "usage:" (case-insensitive).')
-    options_pattern = re.compile(r"\n\s*?options:", re.IGNORECASE)
-    if options_pattern.search(usage_sections[0]):
-        raise DocoptExit(
-            "Warning: options (case-insensitive) was found in usage."
+    if parse_section("options:", usage_sections[0]):
+        raise DocoptLanguageError(
+            "Warning: options (case-insensitive) was found in usage. "
             "Use a blank line between each section.."
         )
     DocoptExit.usage = usage_sections[0]

tests/test_docopt.py

@@ -638,6 +638,22 @@ def test_language_errors():
         docopt("usage: here \n\n and again usage: here")
 
 
+@pytest.mark.parametrize(
+    "doc",
+    [
+        pytest.param("Usage: prog\n  Options:  --foo\n"),
+        pytest.param("Usage: prog\n  Advanced Options:  --foo\n"),
+    ],
+)
+def test_docopt_reports_options_in_usage_section(doc: str):
+    with raises(
+        DocoptLanguageError,
+        match=r"Warning: options \(case-insensitive\) was found in usage\. "
+        r"Use a blank line between each section\.\.",
+    ):
+        docopt(doc)
+
+
 def test_issue_40(capsys: pytest.CaptureFixture):
     with raises(SystemExit):  # i.e. shows help
         docopt("usage: prog --help-commands | --help", "--help")