Add a -s / --section option to blurb add

CHANGELOG.md

@@ -4,6 +4,8 @@
 
 - Add the `-i` / `--issue` option to the 'blurb add' command.
   This lets you pre-fill the `gh-issue` field in the template.
+- Add the `-s` / `--section` option to the 'blurb add' command.
+  This lets you pre-fill the `section` field in the template.
 
 ## 2.0.0
 

README.md

@@ -120,6 +120,13 @@ Here's how you interact with the file:
   For example, if this should go in the `Library` section, uncomment
   the line reading `#.. section: Library`.  To uncomment, just delete
   the `#` at the front of the line.
+  The section can also be specified via the ``-s`` / ``--section`` option:
+
+  ```shell
+  $ blurb add -s Library
+  # or
+  $ blurb add -s library
+  ```
 
 * Finally, go to the end of the file, and enter your `NEWS` entry.
   This should be a single paragraph of English text using

src/blurb/blurb.py

@@ -851,8 +851,36 @@ def _extract_issue_number(issue, /):
     sys.exit(f"Invalid GitHub issue number: {issue}")
 
 
-def _blurb_template_text(*, issue):
+def _extract_section_name(section, /):
+    if section is None:
+        return None
+
+    section = section.strip()
+    if not section:
+        sys.exit("Empty section name!")
+
+    matches = []
+    # Try an exact or lowercase match
+    for section_name in sections:
+        if section in {section_name, section_name.lower()}:
+            matches.append(section_name)
+
+    if not matches:
+        section_list = '\n'.join(f'* {s}' for s in sections)
+        sys.exit(f"Invalid section name: {section!r}\n\n"
+                 f"Valid names are:\n\n{section_list}")
+
+    if len(matches) > 1:
+        multiple_matches = ', '.join(f'* {m}' for m in sorted(matches))
+        sys.exit(f"More than one match for {section!r}:\n\n"
+                 f"{multiple_matches}")
+
+    return matches[0]
+
+
+def _blurb_template_text(*, issue, section):
     issue_number = _extract_issue_number(issue)
+    section_name = _extract_section_name(section)
 
     text = template
 
@@ -870,11 +898,16 @@ def _blurb_template_text(*, issue):
         with_issue_number = f"\n{issue_line} {issue_number}\n"
         text = text.replace(without_space, with_issue_number)
 
+    # Uncomment the section if needed.
+    if section_name is not None:
+        pattern = f'.. section: {section_name}'
+        text = text.replace(f'#{pattern}', pattern)
+
     return text
 
 
 @subcommand
-def add(*, issue=None):
+def add(*, issue=None, section=None):
     """
 Add a blurb (a Misc/NEWS.d/next entry) to the current CPython repo.
 
@@ -883,6 +916,17 @@ def add(*, issue=None):
     blurb add -i 12345
     # or
     blurb add -i https://github.com/python/cpython/issues/12345
+
+Use -s/--section to specify the section name (case-insensitive), e.g.:
+
+    blurb add -s Library
+    # or
+    blurb add -s library
+
+The known sections names are defined as follows and
+spaces in names can be substituted for underscores:
+
+{sections}
     """
 
     editor = find_editor()
@@ -891,7 +935,7 @@ def add(*, issue=None):
     os.close(handle)
     atexit.register(lambda : os.unlink(tmp_path))
 
-    text = _blurb_template_text(issue=issue)
+    text = _blurb_template_text(issue=issue, section=section)
     with open(tmp_path, "w", encoding="utf-8") as file:
         file.write(text)
 
@@ -940,7 +984,7 @@ def add(*, issue=None):
     git_add_files.append(path)
     flush_git_add_files()
     print("Ready for commit.")
-
+add.__doc__ = add.__doc__.format(sections='\n'.join(f'* {s}' for s in sections))
 
 
 @subcommand

tests/test_blurb_add.py

@@ -7,7 +7,7 @@
 
 def test_valid_no_issue_number():
     assert blurb._extract_issue_number(None) is None
-    res = blurb._blurb_template_text(issue=None)
+    res = blurb._blurb_template_text(issue=None, section=None)
     lines = frozenset(res.splitlines())
     assert '.. gh-issue:' not in lines
     assert '.. gh-issue: ' in lines
@@ -37,7 +37,7 @@ def test_valid_issue_number_12345(issue):
     actual = blurb._extract_issue_number(issue)
     assert actual == 12345
 
-    res = blurb._blurb_template_text(issue=issue)
+    res = blurb._blurb_template_text(issue=issue, section=None)
     lines = frozenset(res.splitlines())
     assert '.. gh-issue:' not in lines
     assert '.. gh-issue: ' not in lines
@@ -70,7 +70,7 @@ def test_valid_issue_number_12345(issue):
 def test_invalid_issue_number(issue):
     error_message = re.escape(f'Invalid GitHub issue number: {issue}')
     with pytest.raises(SystemExit, match=error_message):
-        blurb._blurb_template_text(issue=issue)
+        blurb._blurb_template_text(issue=issue, section=None)
 
 
 @pytest.mark.parametrize('invalid', (
@@ -84,4 +84,80 @@ def test_malformed_gh_issue_line(invalid, monkeypatch):
     with monkeypatch.context() as cm:
         cm.setattr(blurb, 'template', template)
         with pytest.raises(SystemExit, match=error_message):
-            blurb._blurb_template_text(issue='1234')
+            blurb._blurb_template_text(issue='1234', section=None)
+
+
+def _check_section_name(section_name, expected):
+    actual = blurb._extract_section_name(section_name)
+    assert actual == expected
+
+    res = blurb._blurb_template_text(issue=None, section=section_name)
+    res = res.splitlines()
+    for section_name in blurb.sections:
+        if section_name == expected:
+            assert f'.. section: {section_name}' in res
+        else:
+            assert f'#.. section: {section_name}' in res
+            assert f'.. section: {section_name}' not in res
+
+
+@pytest.mark.parametrize(
+    ('section_name', 'expected'),
+    [(name, name) for name in blurb.sections],
+)
+def test_exact_names(section_name, expected):
+    _check_section_name(section_name, expected)
+
+
+@pytest.mark.parametrize(
+    ('section_name', 'expected'),
+    [(name.lower(), name) for name in blurb.sections],
+)
+def test_exact_names_lowercase(section_name, expected):
+    _check_section_name(section_name, expected)
+
+
+@pytest.mark.parametrize('section', (
+    '',
+    ' ',
+    '\t',
+    '\n',
+    '\r\n',
+    '      ',
+))
+def test_empty_section_name(section):
+    error_message = re.escape('Empty section name!')
+    with pytest.raises(SystemExit, match=error_message):
+        blurb._extract_section_name(section)
+
+    with pytest.raises(SystemExit, match=error_message):
+        blurb._blurb_template_text(issue=None, section=section)
+
+
+@pytest.mark.parametrize('section', [
+    # Wrong capitalisation
+    'C api',
+    'c API',
+    'LibrarY',
+    # Invalid
+    '_',
+    '-',
+    '/',
+    'invalid',
+    'Not a section',
+    # Non-special names
+    'c?api',
+    'cXapi',
+    'C+API',
+    # Super-strings
+    'Library and more',
+    'library3',
+    'librari',
+])
+def test_invalid_section_name(section):
+    error_message = rf"(?m)Invalid section name: '{re.escape(section)}'\n\n.+"
+    with pytest.raises(SystemExit, match=error_message):
+        blurb._extract_section_name(section)
+
+    with pytest.raises(SystemExit, match=error_message):
+        blurb._blurb_template_text(issue=None, section=section)