Skip the checks if the news file was changed

README.rst

@@ -163,3 +163,17 @@ Furthermore, you can add your own fragment types using:
     directory = "deprecation"
     name = "Deprecations"
     showcontent = true
+
+
+Automatic pull request checks
+-----------------------------
+
+To check if a feature branch adds at least one news fragment, run::
+
+    towncrier check
+
+By default this compares the current branch against ``origin/master``. You can use ``--compare-with`` if the trunk is named differently::
+
+    towncrier check --compare-with origin/main
+
+The check is automatically skipped when the main news file is modified inside the branch as this signals a release branch that is expected to not have news fragments.

src/towncrier/check.py

@@ -66,6 +66,11 @@ def __main(comparewith, directory, config):
         click.echo("{}. {}".format(n, change))
     click.echo("----")
 
+    news_file = os.path.normpath(os.path.join(base_directory, config["filename"]))
+    if news_file in files:
+        click.echo("Checks SKIPPED: news file changes detected.")
+        sys.exit(0)
+
     if config.get("directory"):
         fragment_base_directory = os.path.abspath(config["directory"])
         fragment_directory = None

src/towncrier/newsfragments/337.feature.rst

@@ -0,0 +1,5 @@
+Make the check subcommand succeed for branches that change the news file
+
+This should enable the ``check`` subcommand to be used as a CI lint step and
+not fail when a pull request only modifies the configured news file (i.e. when
+the news file is being assembled for the next release).

src/towncrier/test/test_check.py

@@ -2,6 +2,7 @@
 # See LICENSE for details.
 
 import os
+import os.path
 import sys
 
 from twisted.trial.unittest import TestCase
@@ -30,6 +31,29 @@ def create_project(pyproject_path):
     call(["git", "checkout", "-b", "otherbranch"])
 
 
+def commit(message):
+    call(["git", "add", "."])
+    call(["git", "commit", "-m", message])
+
+
+def write(path, contents):
+    dir = os.path.dirname(path)
+    if dir:
+        try:
+            os.makedirs(dir)
+        except OSError:
+            pass
+    with open(path, "w") as f:
+        f.write(contents)
+
+
+def initial_commit():
+    call(["git", "init", "--initial-branch=main"])
+    call(["git", "config", "user.name", "user"])
+    call(["git", "config", "user.email", "user@example.com"])
+    commit("Initial Commit")
+
+
 class TestChecker(TestCase):
     maxDiff = None
 
@@ -148,3 +172,54 @@ def test_none_stdout_encoding_works(self):
 
         self.assertEqual(0, proc.returncode)
         self.assertEqual(b"", stderr)
+
+    def test_first_release(self):
+        """The checks should be skipped on a branch that creates the news file.
+
+        If the checkes are not skipped in this case, towncrier check would fail
+        for the first release that has a changelog"""
+        runner = CliRunner()
+
+        with runner.isolated_filesystem():
+            # Arrange
+            write("towncrier.toml", "[tool.towncrier]")
+            write("newsfragments/123.feature", "Foo the bar")
+            initial_commit()
+
+            call(["git", "checkout", "-b", "next-resease"])
+            call(["towncrier", "--yes", "--version", "1.0"])
+            commit("Prepare a release")
+
+            # Act
+            result = runner.invoke(_main, ["--compare-with", "main"])
+
+            # Assert
+            self.assertEqual(0, result.exit_code, (result, result.output))
+            self.assertIn("Checks SKIPPED: news file changes detected", result.output)
+
+    def test_second_release(self):
+        """The checks should be skipped on a branch that modifies the news file."""
+        runner = CliRunner()
+
+        with runner.isolated_filesystem():
+            # Arrange
+            write("towncrier.toml", "[tool.towncrier]")
+            write("newsfragments/.gitignore", "!.gitignore")
+            initial_commit()
+
+            call(["towncrier", "--yes", "--version", "1.0"])
+            commit("First release")
+
+            write("newsfragments/123.feature", "Foo the bar")
+            commit("Foo the bar")
+
+            call(["git", "checkout", "-b", "next-resease"])
+            call(["towncrier", "--yes", "--version", "2.0"])
+            commit("Second release")
+
+            # Act
+            result = runner.invoke(_main, ["--compare-with", "main"])
+
+            # Assert
+            self.assertEqual(0, result.exit_code, (result, result.output))
+            self.assertIn("Checks SKIPPED: news file changes detected", result.output)