Add tests, docs, and implementation for #133307

Author: makukha

Doc/library/pdb.rst

@@ -378,12 +378,20 @@ There are four preset *convenience variables*:
    pair: .pdbrc; file
    triple: debugger; configuration; file
 
-If a file :file:`.pdbrc` exists in the user's home directory or in the current
-directory, it is read with ``'utf-8'`` encoding and executed as if it had been
-typed at the debugger prompt, with the exception that empty lines and lines
-starting with ``#`` are ignored.  This is particularly useful for aliases.  If both
-files exist, the one in the home directory is read first and aliases defined there
-can be overridden by the local file.
+If a file :file:`.pdbrc` exists in any of the supported locations, it is read
+with ``'utf-8'`` encoding and executed as if it had been typed at the debugger
+prompt, with the exception that empty lines and lines starting with ``#`` are
+ignored.  This is particularly useful for aliases.  Supported locations for
+:file:`.pdbrc` file are
+
+1. ``$XDG_CONFIG_HOME/pdb`` (defaults to ``~/.config/pdb``, if environment
+   variable :envvar:`XDG_CONFIG_HOME` is not set)
+2. User's home directory
+3. Current working directory
+
+If :file:`.pdbrc` files exist in multiple locations, they are processed in
+order, so that ``$XDG_CONFIG_HOME/pdb/.pdbrc`` is loaded first, and extended
+by :file:`.pdbrc` files in user's home and current directory.
 
 .. versionchanged:: 3.2
    :file:`.pdbrc` can now contain commands that continue debugging, such as
@@ -394,6 +402,10 @@ can be overridden by the local file.
    :file:`.pdbrc` is now read with ``'utf-8'`` encoding. Previously, it was read
    with the system locale encoding.
 
+.. versionadded:: 3.15
+   :file:`.pdbrc` is now searched in ``$XDG_CONFIG_HOME/pdb`` directory first.
+   Previously, this location was ignored.
+
 
 .. pdbcommand:: h(elp) [command]
 

Lib/pdb.py

@@ -46,12 +46,24 @@
 input is split at the first ';;', even if it is in the middle of a
 quoted string.
 
-If a file ".pdbrc" exists in your home directory or in the current
-directory, it is read in and executed as if it had been typed at the
-debugger prompt.  This is particularly useful for aliases.  If both
-files exist, the one in the home directory is read first and aliases
-defined there can be overridden by the local file.  This behavior can be
-disabled by passing the "readrc=False" argument to the Pdb constructor.
+If a '.pdbrc' exists in any of the supported locations, it is read with 'utf-8'
+encoding and executed as if it had been typed at the debugger prompt, with the
+exception that empty lines and lines starting with '#' are ignored.  This is
+particularly useful for aliases.
+
+This behavior can be disabled by passing the 'readrc=False' argument to the Pdb
+constructor.
+
+Supported locations for '.pdbrc' file are
+
+1. '$XDG_CONFIG_HOME/pdb' (defaults to '~/.config/pdb', if environment variable
+    $XDG_CONFIG_HOME is not set)
+2. User's home directory
+3. Current working directory
+
+If '.pdbrc' files exist in multiple locations, they are processed in order, so
+that '$XDG_CONFIG_HOME/pdb/.pdbrc' is loaded first, and extended by '.pdbrc'
+files in user's home and current directory.
 
 Aside from aliases, the debugger is not directly programmable; but it
 is implemented as a class from which you can derive your own debugger
@@ -98,7 +110,7 @@
 import _colorize
 import _pyrepl.utils
 
-from contextlib import ExitStack, closing, contextmanager
+from contextlib import ExitStack, closing, contextmanager, suppress
 from rlcompleter import Completer
 from types import CodeType
 from warnings import deprecated
@@ -369,19 +381,19 @@ def __init__(self, completekey='tab', stdin=None, stdout=None, skip=None,
         # c.a or c['a'], it won't be recognized as a c(ontinue) command
         self.identchars = cmd.Cmd.identchars + '=.[](),"\'+-*/%@&|<>~^'
 
-        # Read ~/.pdbrc and ./.pdbrc
+        # Read $XDG_CONFIG_HOME/pdb/.pdbrc, ~/.pdbrc, and ./.pdbrc
         self.rcLines = []
         if readrc:
-            try:
-                with open(os.path.expanduser('~/.pdbrc'), encoding='utf-8') as rcFile:
-                    self.rcLines.extend(rcFile)
-            except OSError:
-                pass
-            try:
-                with open(".pdbrc", encoding='utf-8') as rcFile:
-                    self.rcLines.extend(rcFile)
-            except OSError:
-                pass
+            # $XDG_CONFIG_HOME defaults to $HOME/.config
+            config_home = os.environ.get('XDG_CONFIG_HOME', '~/.config')
+            for rc_path in (
+                os.path.expanduser(os.path.join(config_home, 'pdb', '.pdbrc')),
+                os.path.expanduser('~/.pdbrc'),
+                '.pdbrc',
+            ):
+                with suppress(OSError):
+                    with open(rc_path, encoding='utf-8') as rcFile:
+                        self.rcLines.extend(rcFile)
 
         self.commands = {} # associates a command list to breakpoint numbers
         self.commands_defining = False # True while in the process of defining
@@ -3492,8 +3504,8 @@ def help():
 an executable module or package to debug can be specified using
 the -m switch.
 
-Initial commands are read from .pdbrc files in your home directory
-and in the current directory, if they exist.  Commands supplied with
+Initial commands are read from .pdbrc files in "$XDG_CONFIG_HOME/pdb", your home
+directory, and in the current directory, if they exist.  Commands supplied with
 -c are executed after commands from .pdbrc files.
 
 To let the script run until an exception occurs, use "-c continue".

Lib/test/test_pdb.py

@@ -3935,6 +3935,41 @@ def test_readrc_homedir(self):
                     f.write("invalid")
                 self.assertEqual(pdb.Pdb().rcLines[0], "invalid")
 
+    def test_pdbrc_xdg_config_home(self):
+        with (
+            os_helper.temp_dir() as temp_dir,
+            os_helper.change_cwd(temp_dir),
+            os_helper.EnvironmentVarGuard() as env,
+            patch(
+                'os.path.expanduser',
+                lambda p: p.replace('~', os.environ.get('HOME', '~')),
+            ),
+        ):
+            for rc_dir, rcLines in (
+                (os.path.join(temp_dir, 'xdg', '.config', 'pdb'), '#xdgconf'),
+                (os.path.join(temp_dir, 'home', '.config', 'pdb'), '#homeconf'),
+                (os.path.join(temp_dir, 'home'), '#home'),
+                (temp_dir, '#cwd'),
+            ):
+                if not os.path.exists(rc_dir):
+                    os.makedirs(rc_dir)
+                with open(os.path.join(rc_dir, '.pdbrc'), 'w') as f:
+                    f.write(rcLines)
+
+            env.unset('HOME')
+            env.unset('XDG_CONFIG_HOME')
+
+            # when both XDG_CONFIG_HOME and $HOME are unset, ./.pdbrc is still loaded
+            self.assertListEqual(pdb.Pdb().rcLines, ['#cwd'])
+            # # when XDG_CONFIG_HOME is unset, it defaults to $HOME/.config
+            env.set('HOME', os.path.join(temp_dir, 'home'))
+            self.assertListEqual(pdb.Pdb().rcLines, ['#homeconf', '#home', '#cwd'])
+            # when XDG_CONFIG_HOME is set, .pdbrc is loaded from there
+            env.set('XDG_CONFIG_HOME', os.path.join(temp_dir, 'xdg', '.config'))
+            self.assertListEqual(pdb.Pdb().rcLines, ['#xdgconf', '#home', '#cwd'])
+            # when readrc=False, .pdbrc is not loaded from any location
+            self.assertListEqual(pdb.Pdb(readrc=False).rcLines, [])
+
     def test_header(self):
         stdout = StringIO()
         header = 'Nobody expects... blah, blah, blah'