Refactor _writer & bring to 100% coverage

README.rst

@@ -158,7 +158,7 @@ as the option 'title_format', already exists in newsfile, ``ValueError`` will be
 you "already produced newsfiles for this version".
 
 If ``single_file`` is set to ``false`` instead, each versioned ``towncrier build`` will generate a
-separate newsfile, whose name is formatted as the patten given by option ``filename``.
+separate newsfile, whose name is formatted as the pattern given by option ``filename``.
 For example, if ``filename="{version}-notes.rst"``, then the release note with version "7.8.9" will
 be written to the file "7.8.9-notes.rst". If the newsfile already exists, its content
 will be overwriten with new release note, without throwing a ``ValueError`` warning.

src/towncrier/_writer.py

@@ -11,33 +11,55 @@
 
 
 def append_to_newsfile(
- directory, filename, start_string, top_line, content, single_file=True
+ directory, filename, start_string, top_line, content, single_file
 ):
+ """
+ Write *content* to *directory*/*filename* behind *start_string*.
 
+ Double-check *top_line* (i.e. the release header) is not already in the
+ file.
+
+ if *single_file* is True, add it to an existing file, otherwise create a
+ fresh one.
+ """
  news_file = os.path.join(directory, filename)
 
- if single_file:
- if not os.path.exists(news_file):
- existing_content = ""
- else:
- with open(news_file, encoding="utf8") as f:
- existing_content = f.read()
- existing_content = existing_content.split(start_string, 1)
- else:
- existing_content = [""]
-
- if top_line and top_line in existing_content[-1]:
+ header, prev_body = _figure_out_existing_content(
+ news_file, start_string, single_file
+ )
+
+ if top_line and top_line in prev_body:
  raise ValueError("It seems you've already produced newsfiles for this version?")
 
- with open(os.path.join(directory, filename), "wb") as f:
+ with open(news_file, "w", encoding="utf8") as f:
+ if header:
+ f.write(header)
+
+ f.write(content)
+
+ if prev_body:
+ f.write(f"\n\n{prev_body}")
+
+
+def _figure_out_existing_content(news_file, start_string, single_file):
+ """
+ Try to read *news_file* and split it into header (everything before
+ *start_string*) and the old body (everything after *start_string*).
+
+ If there's no *start_string*, return empty header.
+
+ Empty file and per-release files have neither.
+ """
+ if not single_file or not os.path.exists(news_file):
+ # Per-release news files always start empty.
+ # Non-existent files have no existing content.
+ return "", ""
+
+ with open(news_file, encoding="utf8") as f:
+ content = f.read()
 
- if len(existing_content) > 1:
- f.write(existing_content.pop(0).rstrip().encode("utf8"))
- if start_string:
- f.write(("\n\n" + start_string + "\n").encode("utf8"))
+ t = content.split(start_string, 1)
+ if len(t) == 2:
+ return f"{t[0].rstrip()}\n\n{start_string}\n", t[1].lstrip()
 
- f.write(content.encode("utf8"))
- if existing_content:
- if existing_content[0]:
- f.write(b"\n\n")
- f.write(existing_content[0].lstrip().encode("utf8"))
+ return "", content.lstrip()

src/towncrier/test/test_build.py

@@ -717,6 +717,7 @@ def do_build_once_with(version, fragment_file, fragment):
  "01-01-2001",
  "--yes",
  ],
+ catch_exceptions=False,
  )
  # not git repository, manually remove fragment file
  Path(f"newsfragments/{fragment_file}").unlink()
@@ -1010,7 +1011,7 @@ def test_start_string(self):
  with open("newsfragments/123.feature", "w") as f:
  f.write("Adds levitation")
  with open("NEWS.rst", "w") as f:
- f.write("a line\n\nanother\n\nRelease notes start marker\n")
+ f.write("a line\n\nanother\n\nRelease notes start marker\na footer!\n")
 
  result = runner.invoke(
  _main,
@@ -1045,6 +1046,7 @@ def test_start_string(self):
  - Adds levitation (#123)
 
 
+ a footer!
  """
  )
 

src/towncrier/test/test_write.py

@@ -109,6 +109,7 @@ def test_append_at_top(self):
  wrap=True,
  versiondata={"name": "MyProject", "version": "1.0", "date": "never"},
  ),
+ True,
  )
 
  with open(os.path.join(tempdir, "NEWS.rst")) as f:
@@ -221,6 +222,7 @@ def test_append_at_top_with_hint(self):
  wrap=True,
  versiondata={"name": "MyProject", "version": "1.0", "date": "never"},
  ),
+ True,
  )
 
  with open(os.path.join(tempdir, "NEWS.rst")) as f:
@@ -259,6 +261,7 @@ def test_multiple_file_no_start_string(self):
  start_string=None,
  top_line="",
  content=content,
+ single_file=True,
  )
 
  with open(os.path.join(tempdir, "NEWS.rst")) as f: