chdir() not intercepted — fails on mocked directories

[toddr-bot]

Summary

chdir() is not overridden via CORE::GLOBAL::chdir, so calling chdir on a mocked directory falls through to the real filesystem and fails with ENOENT, even when -d confirms the mock directory exists.

Reproduction

use Test::MockFile;

my $dir = Test::MockFile->new_dir("/tmp/mock_chdir_test");

print -d "/tmp/mock_chdir_test" ? "exists" : "missing";  # "exists"
chdir("/tmp/mock_chdir_test") or warn "chdir failed: $!";  # fails: No such file or directory

Impact

Code under test that uses chdir before relative file operations won't work correctly with mocked directories. This includes:

• Programs that chdir into a working directory before processing files
• Build tools and installers that change directories
• Any code pattern like chdir($dir); open(my $fh, '<', 'config.yml')

Implementation notes

CORE::GLOBAL::chdir is overridable (unlike fcntl/ioctl). A mock chdir would need to:

1. Track a "virtual cwd" when the target is a mocked directory
2. Use the virtual cwd in _abs_path_to_file() for resolving relative paths
3. Fall through to CORE::chdir for non-mocked directories
4. Handle chdir() with no args ($ENV{HOME}) and chdir("-") (previous dir)
5. Override Cwd::cwd/Cwd::getcwd to return the virtual cwd when active

This is non-trivial because it changes how ALL relative path resolution works. It might be better suited for the MockFileSys layer (#115) rather than the base module.

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🤖 Found by Kōan during file-operation audit