DOC: Adding validation of the section order in docstrings (pandas-dev…

…#23607)

* Adding validation of the section order in docstrings

* Updating allowed sections

scripts/tests/test_validate_docstrings.py

@@ -350,6 +350,35 @@ def private_classes(self):
         This mentions NDFrame, which is not correct.
         """
 
+    def unknown_section(self):
+        """
+        This section has an unknown section title.
+
+        Unknown Section
+        ---------------
+        This should raise an error in the validation.
+        """
+
+    def sections_in_wrong_order(self):
+        """
+        This docstring has the sections in the wrong order.
+
+        Parameters
+        ----------
+        name : str
+            This section is in the right position.
+
+        Examples
+        --------
+        >>> print('So far Examples is good, as it goes before Parameters')
+        So far Examples is good, as it goes before Parameters
+
+        See Also
+        --------
+        function : This should generate an error, as See Also needs to go
+            before Examples.
+        """
+
 
 class BadSummaries(object):
 
@@ -706,6 +735,11 @@ def test_bad_generic_functions(self, func):
         ('BadGenericDocStrings', 'private_classes',
          ("Private classes (NDFrame) should not be mentioned in public "
           'docstrings',)),
+        ('BadGenericDocStrings', 'unknown_section',
+         ('Found unknown section "Unknown Section".',)),
+        ('BadGenericDocStrings', 'sections_in_wrong_order',
+         ('Wrong order of sections. "See Also" should be located before '
+          '"Notes"',)),
         ('BadSeeAlso', 'desc_no_period',
          ('Missing period at end of description for See Also "Series.iloc"',)),
         ('BadSeeAlso', 'desc_first_letter_lowercase',

scripts/validate_docstrings.py

@@ -56,6 +56,9 @@
 
 PRIVATE_CLASSES = ['NDFrame', 'IndexOpsMixin']
 DIRECTIVES = ['versionadded', 'versionchanged', 'deprecated']
+ALLOWED_SECTIONS = ['Parameters', 'Attributes', 'Methods', 'Returns', 'Yields',
+                    'Other Parameters', 'Raises', 'Warns', 'See Also', 'Notes',
+                    'References', 'Examples']
 ERROR_MSGS = {
     'GL01': 'Docstring text (summary) should start in the line immediately '
             'after the opening quotes (not in the same line, or leaving a '
@@ -69,6 +72,10 @@
             'mentioned in public docstrings',
     'GL05': 'Tabs found at the start of line "{line_with_tabs}", please use '
             'whitespace only',
+    'GL06': 'Found unknown section "{section}". Allowed sections are: '
+            '{allowed_sections}',
+    'GL07': 'Wrong order of sections. "{wrong_section}" should be located '
+            'before "{goes_before}", the right order is: {sorted_sections}',
     'SS01': 'No summary found (a short summary in a single line should be '
             'present at the beginning of the docstring)',
     'SS02': 'Summary does not start with a capital letter',
@@ -353,6 +360,18 @@ def double_blank_lines(self):
             prev = row.strip()
         return False
 
+    @property
+    def section_titles(self):
+        sections = []
+        self.doc._doc.reset()
+        while not self.doc._doc.eof():
+            content = self.doc._read_to_next_section()
+            if (len(content) > 1
+                    and len(content[0]) == len(content[1])
+                    and set(content[1]) == {'-'}):
+                sections.append(content[0])
+        return sections
+
     @property
     def summary(self):
         return ' '.join(self.doc['Summary'])
@@ -580,6 +599,25 @@ def validate_one(func_name):
         if re.match("^ *\t", line):
             errs.append(error('GL05', line_with_tabs=line.lstrip()))
 
+    unseen_sections = list(ALLOWED_SECTIONS)
+    for section in doc.section_titles:
+        if section not in ALLOWED_SECTIONS:
+            errs.append(error('GL06',
+                              section=section,
+                              allowed_sections=', '.join(ALLOWED_SECTIONS)))
+        else:
+            if section in unseen_sections:
+                section_idx = unseen_sections.index(section)
+                unseen_sections = unseen_sections[section_idx + 1:]
+            else:
+                section_idx = ALLOWED_SECTIONS.index(section)
+                goes_before = ALLOWED_SECTIONS[section_idx + 1]
+                errs.append(error('GL07',
+                                  sorted_sections=' > '.join(ALLOWED_SECTIONS),
+                                  wrong_section=section,
+                                  goes_before=goes_before))
+                break
+
     if not doc.summary:
         errs.append(error('SS01'))
     else: