test: finish pr #22, relative &filelist

CHANGELOG.rst

@@ -23,6 +23,11 @@ Unreleased
 
 - Dropped support for Python 2.7, 3.5, and 3.6, and added 3.11 and 3.12.
 
+- Files listing other files to process can now be specified as
+  ``&files_to_cog.txt`` to interpret the file names relative to the location of
+  the list file.  The existing ``@files_to_cog.txt`` syntax interprets file
+  names relative to the current working directory.  Thanks, Phil Kirkpatrick.
+
 - Removed the ``cog.py`` installed file.  Use the ``cog`` command, or ``python
   -m cogapp`` to run cog.
 

cogapp/cogapp.py

@@ -14,7 +14,7 @@
 import types
 
 from .whiteutils import commonPrefix, reindentBlock, whitePrefix
-from .utils import NumberedFileReader, Redirectable, md5
+from .utils import NumberedFileReader, Redirectable, change_dir, md5
 
 __version__ = "4.0.0.dev2"
 
@@ -724,12 +724,10 @@ def processArguments(self, args):
             self.processFileList(args[0][1:])
         elif args[0][0] == '&':
             if self.options.sOutputName:
-                raise CogUsageError("Can't use -o with @file")
-            saved_cwd = os.getcwd()
+                raise CogUsageError("Can't use -o with &file")
             file_list = args[0][1:]
-            os.chdir(os.path.dirname(file_list))
-            self.processFileList(os.path.basename(file_list))
-            os.chdir(saved_cwd)
+            with change_dir(os.path.dirname(file_list)):
+                self.processFileList(os.path.basename(file_list))
         else:
             self.processWildcards(args[0])
 

cogapp/test_cogapp.py

@@ -808,16 +808,15 @@ def testArgumentFailure(self):
             self.cog.callableMain(['argv0', '-j'])
 
     def testNoDashOAndAtFile(self):
-        d = {
-            'cogfiles.txt': """\
-                # Please run cog
-                """
-            }
-
-        makeFiles(d)
+        makeFiles({"cogfiles.txt": "# Please run cog"})
         with self.assertRaisesRegex(CogUsageError, r"^Can't use -o with @file$"):
             self.cog.callableMain(['argv0', '-o', 'foo', '@cogfiles.txt'])
 
+    def testNoDashOAndAmpFile(self):
+        makeFiles({"cogfiles.txt": "# Please run cog"})
+        with self.assertRaisesRegex(CogUsageError, r"^Can't use -o with &file$"):
+            self.cog.callableMain(['argv0', '-o', 'foo', '&cogfiles.txt'])
+
     def testDashV(self):
         self.assertEqual(self.cog.main(['argv0', '-v']), 0)
         output = self.output.getvalue()
@@ -1346,6 +1345,41 @@ def fix_backslashes(files_txt):
         self.assertFilesSame('subdir/subback.cog', 'subback.out')
         self.assertFilesSame('subdir/subfwd.cog', 'subfwd.out')
 
+    def testAmpFile(self):
+        d = {
+            'code': {
+                'files_to_cog': """\
+                    # A locally resolved file name.
+                    test.cog
+                    """,
+
+                'test.cog': """\
+                    //[[[cog
+                        import myampsubmodule
+                    //]]]
+                    //[[[end]]]
+                    """,
+
+                'test.out': """\
+                    //[[[cog
+                        import myampsubmodule
+                    //]]]
+                    Hello from myampsubmodule
+                    //[[[end]]]
+                    """,
+
+                'myampsubmodule.py': """\
+                    import cog
+                    cog.outl("Hello from myampsubmodule")
+                    """
+                }
+            }
+
+        makeFiles(d)
+        print(os.path.abspath("code/test.out"))
+        self.cog.callableMain(['argv0', '-r', '&code/files_to_cog'])
+        self.assertFilesSame('code/test.cog', 'code/test.out')
+
     def run_with_verbosity(self, verbosity):
         d = {
             'unchanged.cog': """\

cogapp/utils.py

@@ -1,8 +1,10 @@
 """ Utilities for cog.
 """
 
+import contextlib
 import functools
 import hashlib
+import os
 import sys
 
 
@@ -51,3 +53,19 @@ def readline(self):
 
     def linenumber(self):
         return self.n
+
+
+@contextlib.contextmanager
+def change_dir(new_dir):
+    """Change directory, and then change back.
+
+    Use as a context manager, it will return to the original
+    directory at the end of the block.
+
+    """
+    old_dir = os.getcwd()
+    os.chdir(str(new_dir))
+    try:
+        yield
+    finally:
+        os.chdir(old_dir)

docs/running.rst

@@ -87,7 +87,11 @@ with an ``@``:
 
     $ cog @files_to_cog.txt
 
-These @-files can be nested, and each line can contain switches as well as a
+File names in the list file are relative to the current directory. You can also
+use ``&files_to_cog.txt`` and the file names will be relative to the location
+of the list file.
+
+These list files can be nested, and each line can contain switches as well as a
 file to process.  For example, you can create a file cogfiles.txt:
 
 .. code-block:: text