Listing directory entries using execution contexts

executor/__init__.py

@@ -64,7 +64,7 @@
     unicode = str
 
 # Semi-standard module versioning.
-__version__ = '9.2'
+__version__ = '9.3'
 
 # Initialize a logger.
 logger = logging.getLogger(__name__)

executor/contexts.py

@@ -62,6 +62,7 @@ def details_about_system(context):
 # Standard library modules.
 import logging
 import multiprocessing
+import os
 import socket
 
 # External dependencies.
@@ -308,6 +309,21 @@ def write_file(self, filename, contents):
         """
         return self.execute('cat > %s' % quote(filename), shell=True, input=contents)
 
+    def list_entries(self, directory):
+        """
+        List the entries in a directory.
+
+        :param directory: The pathname of the directory (a string).
+        :returns: A list of strings with the names of the directory entries.
+
+        This method uses ``find -mindepth 1 -maxdepth 1 -print0`` to list
+        directory entries instead of going for the more obvious choice ``ls
+        -A1`` because ``find`` enables more reliable parsing of command output
+        (with regards to whitespace).
+        """
+        listing = self.capture('find', directory, '-mindepth', '1', '-maxdepth', '1', '-print0')
+        return [os.path.basename(fn) for fn in listing.split('\0') if fn]
+
     def __enter__(self):
         """Initialize a new "undo stack" (refer to :func:`cleanup()`)."""
         self.undo_stack.append([])

executor/tests.py

@@ -741,6 +741,23 @@ def check_context(self, context):
         # Make sure the contents are correct.
         actual_contents = context.read_file(random_file)
         assert actual_contents == expected_contents
+        # Test context.list_entries() and make sure it doesn't mangle filenames
+        # containing whitespace.
+        nasty_filenames = [
+            'something-innocent',
+            'now with spaces',
+            'and\twith\ttabs',
+            'and\nfinally\nnewlines',
+        ]
+        with TemporaryDirectory() as directory:
+            # Create files with nasty names :-).
+            for filename in nasty_filenames:
+                with open(os.path.join(directory, filename), 'w') as handle:
+                    handle.write('\n')
+            # List the directory entries.
+            parsed_filenames = context.list_entries(directory)
+            # Make sure all filenames were parsed correctly.
+            assert sorted(nasty_filenames) == sorted(parsed_filenames)
 
     def test_cli_usage(self):
         """Make sure the command line interface properly presents its usage message."""