Raise ConfigError for missing newsfragment directory

src/towncrier/_builder.py

@@ -4,6 +4,7 @@
 from __future__ import absolute_import, division, print_function
 
 import os
+import sys
 import textwrap
 
 from collections import OrderedDict
@@ -86,7 +87,15 @@ def find_fragments(base_directory, sections, fragment_directory, definitions):
         else:
             section_dir = os.path.join(base_directory, val)
 
-        files = os.listdir(section_dir)
+        if sys.version_info >= (3,):
+            expected_exception = FileNotFoundError
+        else:
+            expected_exception = OSError
+
+        try:
+            files = os.listdir(section_dir)
+        except expected_exception:
+            files = []
 
         file_content = {}
 

src/towncrier/newsfragments/85.bugfix.rst

@@ -0,0 +1 @@
+A missing newsfragment directory is treated as if it is empty rather than raising an exception.

src/towncrier/test/test_build.py

@@ -12,13 +12,14 @@
 from .._shell import cli
 
 
-def setup_simple_project():
+def setup_simple_project(create_newsfragments_directory=True):
     with open("pyproject.toml", "w") as f:
         f.write("[tool.towncrier]\n" 'package = "foo"\n')
     os.mkdir("foo")
     with open("foo/__init__.py", "w") as f:
         f.write('__version__ = "1.2.3"\n')
-    os.mkdir("foo/newsfragments")
+    if create_newsfragments_directory:
+        os.mkdir("foo/newsfragments")
 
 
 class TestCli(TestCase):
@@ -82,6 +83,36 @@ def test_command(self):
     def test_subcommand(self):
         self._test_command(_main)
 
+    def test_no_newsfragment_directory(self):
+        """
+        A missing newsfragment directory acts as if there are no changes.
+        """
+        runner = CliRunner()
+
+        with runner.isolated_filesystem():
+            setup_simple_project(create_newsfragments_directory=False)
+
+            result = runner.invoke(_main, ["--draft", "--date", "01-01-2001"])
+
+        # This should fail
+        self.assertEqual(result.exit_code, 0)
+        self.assertIn("No significant changes.\n", result.output)
+
+    def test_no_newsfragments(self):
+        """
+        An empty newsfragment directory acts as if there are no changes.
+        """
+        runner = CliRunner()
+
+        with runner.isolated_filesystem():
+            setup_simple_project(create_newsfragments_directory=True)
+
+            result = runner.invoke(_main, ["--draft", "--date", "01-01-2001"])
+
+        # This should fail
+        self.assertEqual(result.exit_code, 0)
+        self.assertIn("No significant changes.\n", result.output)
+
     def test_collision(self):
         runner = CliRunner()