--- a/vcssync/mozvcssync/cli.py
+++ b/vcssync/mozvcssync/cli.py
@@ -7,18 +7,20 @@ from __future__ import absolute_import, 
 import argparse
 import logging
 import os
 import subprocess
 import sys
 
 import dulwich.repo
 import hglib
+import pathlib2 as pathlib
 
 from .git2hg import (
+    copy_git_workdir_to_hg_workdir,
     linearize_git_repo_to_hg,
 )
 from .gitrewrite import (
     RewriteError,
     commit_metadata_rewriter,
 )
 from .gitrewrite.linearize import (
     linearize_git_repo,
@@ -26,16 +28,19 @@ from .gitrewrite.linearize import (
 from .overlay import (
     overlay_hg_repos,
     PushRaceError,
     PushRemoteFail,
 )
 from .servo_backout import (
     backout_servo_pr,
 )
+from .util import (
+    synchronize_directories,
+)
 
 logger = logging.getLogger(__name__)
 
 
 LINEARIZE_GIT_ARGS = [
     (('--exclude-dir',), dict(action='append', dest='exclude_dirs',
                               help='Directory to exclude from rewritten '
                                    'history')),
@@ -317,8 +322,61 @@ def servo_backout_pr_cli():
             args.github_repo_path,
             args.author,
             args.tracking_s3_upload_url,
             args.revision,
         )
     except Exception as e:
         logger.exception(e)
         sys.exit(1)
+
+
+def test_synchronize_directories():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--map', action='append',
+                        help='source:dest directory mapping')
+    parser.add_argument('source')
+    parser.add_argument('dest')
+
+    args = parser.parse_args()
+
+    source_files = []
+    base = pathlib.PosixPath(args.source)
+    for p in base.glob('**/*'):
+        if p == base:
+            continue
+
+        if p.is_dir():
+            continue
+
+        source_files.append(bytes(p.relative_to(base)))
+
+    dir_map = {}
+    for e in args.map or []:
+        k, v = e.split(':')
+        dir_map[k] = v
+
+    try:
+        synchronize_directories(args.source, source_files, args.dest, dir_map)
+    except Exception as e:
+        print('%s: %s' % (e.__class__.__name__, e))
+        sys.exit(1)
+
+
+def test_copy_workdir_git_to_hg():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--map', action='append',
+                        help='source:dest directory mapping')
+    parser.add_argument('source')
+    parser.add_argument('dest')
+
+    args = parser.parse_args()
+
+    dir_map = {}
+    for e in args.map or []:
+        k, v = e.split(':')
+        dir_map[k] = v
+
+    try:
+        copy_git_workdir_to_hg_workdir(args.source, args.dest, dir_map)
+    except Exception as e:
+        print('%s: %s' % (e.__class__.__name__, e))
+        sys.exit(1)

--- a/vcssync/mozvcssync/git2hg.py
+++ b/vcssync/mozvcssync/git2hg.py
@@ -16,16 +16,17 @@ import hglib
 from .gitrewrite import (
     commit_metadata_rewriter,
 )
 from .gitrewrite.linearize import (
     linearize_git_repo,
 )
 from .util import (
     monitor_hg_repo,
+    synchronize_directories,
 )
 
 
 logger = logging.getLogger(__name__)
 
 
 def source_commits_in_map_file(path, commits):
     """Determine whether all source commits are present in a map file.
@@ -286,8 +287,45 @@ def linearize_git_repo_to_hg(git_source_
 
     # TODO so hacky. Relies on credentials in the environment.
     if shamap_s3_upload_url and shamap_changed:
         subprocess.check_call([
             b'aws', b's3', b'cp', rev_map, shamap_s3_upload_url
         ])
 
     return result
+
+
+def copy_git_workdir_to_hg_workdir(git_repo_path, hg_repo_path, dir_map=None):
+    """Copy files between Git and Mercurial working directories.
+
+    Given paths to Git and Mercurial repos that have working directories,
+    synchronize the contents of the Git working directory to the Mercurial
+    working directory, optionally remapping paths to directories using
+    ``dir_map``.
+
+    See ``util.synchronize_directories()`` for behavior of ``dir_map``.
+
+    Only files tracked by Git are copied. This therefore differs from a pure
+    filesystem recursive copy.
+
+    The changes to the Mercurial working directory are left uncommitted.
+
+    Returns a bool indicating if there are changes to be committed.
+    """
+    git_files = subprocess.check_output([b'git', b'ls-files', b'-z'],
+                                        cwd=git_repo_path)
+    git_files = [f for f in git_files.split(b'\0') if f]
+
+    synchronize_directories(git_repo_path, git_files, hg_repo_path,
+                            dir_map=dir_map)
+
+    have_changes = False
+
+    configs = [b'extensions.automv=']
+    with hglib.open(hg_repo_path, encoding='utf-8', configs=configs) as hrepo:
+        hrepo.addremove()
+        for code, path in hrepo.status():
+            if code in (b'M', b'A', b'R'):
+                have_changes = True
+                break
+
+    return have_changes

--- a/vcssync/mozvcssync/util.py
+++ b/vcssync/mozvcssync/util.py
@@ -10,16 +10,18 @@ import hashlib
 import logging
 import os
 import pipes
 import shutil
 import sys
 
 import github3
 import hglib
+import pathlib2 as pathlib
+import scandir
 
 
 def run_hg(logger, client, args):
     """Run a Mercurial command through hgclient and log output."""
     logger.warn('executing: hg %s' % ' '.join(map(pipes.quote, args)))
     out = hglib.util.BytesIO()
 
     def write(data):
@@ -170,8 +172,149 @@ def apply_changes_from_list(logger, sour
 
 def test_apply_changes_from_list():
     logger = logging.getLogger('mozvcssync')
     logger.addHandler(logging.StreamHandler(sys.stdout))
     logger.setLevel(logging.INFO)
     source_path, dest_path, filelist = sys.argv[1::]
     apply_changes_from_list(logger,
                             source_path, dest_path, filelist.split(','))
+
+
+def resolve_all_dirs(paths):
+    """Resolve all relative directories given an iterable of paths.
+
+    Returns a set of ``pathlib.PurePosixPath`` instances consisting of all
+    directories (including parents) seen in the passed set of paths.
+
+    It is assumed that all paths are files - not directories.
+
+    The root directory (``/`` if absolute paths are passed and ``.`` if relative
+    paths) will be present in the returned set.
+    """
+    dirs = set()
+    for f in paths:
+        p = pathlib.PurePosixPath(f)
+        for parent in p.parents:
+            dirs.add(parent)
+
+    return dirs
+
+
+def rmtree_except_vcs(path):
+    """Recursively delete a directory except for VCS directories.
+
+    The specified base directory is not itself deleted.
+    """
+    try:
+        it = scandir.scandir(path)
+    except OSError as e:
+        if e.errno == errno.ENOENT:
+            return
+        raise
+
+    for entry in it:
+        if entry.is_dir():
+            if entry.name in ('.hg', '.git'):
+                continue
+
+            shutil.rmtree(entry.path)
+        else:
+            pathlib.Path(entry.path).unlink()
+
+
+def synchronize_directories(source_base, source_files, dest_base, dir_map=None):
+    """Synchronize the contents of directories.
+
+    This function is meant to be used to synchronize the contents of Git and
+    Mercurial working directories.
+
+    It takes two pairs of (dir, files) arguments, defining the base directory
+    and an iterable of files in those directories.
+
+    ``dir_map`` defines a mapping of directory paths in the source to paths
+    in the dest. If provided, only the destination directories will be possibly
+    mutated during execution. Otherwise, the entire set of files is
+    synchronized.
+
+    Files in the destination that aren't accounted for in the source are
+    removed. New files and file modifications are performed as necessary. File
+    permissions and owners are preserved.
+
+    Symlinks are not yet handled properly in all cases. If a symlink exists in
+    the source, behavior is not defined.
+    """
+    source_files = set(source_files)
+
+    # Do a full sync. We could probably use rsync. But since our source files
+    # are defined explicitly and may not resemble actual filesystem contents,
+    # we'd have to use an rsync rules file. At the point we have that
+    # complexity, it is only slightly more difficult to inline in Python.
+    if not dir_map:
+        rmtree_except_vcs(dest_base)
+
+        rel_dirs = resolve_all_dirs(source_files)
+        rel_dirs.remove(pathlib.PurePosixPath('.'))
+
+        for rel_dir in sorted(rel_dirs, key=lambda x: len(bytes(x))):
+            p = pathlib.Path(dest_base, rel_dir)
+            p.mkdir()
+
+        for f in sorted(source_files):
+            source = pathlib.Path(source_base, f)
+            dest = pathlib.Path(dest_base, f)
+            shutil.copy2(bytes(source), bytes(dest))
+
+        return
+
+    # We must have a directory map.
+    #
+    # First some validation.
+
+    if len(set(dir_map.values())) != len(dir_map):
+        raise ValueError('cannot map multiple inputs to same output')
+
+    # Let's find the relevant source files and map them to outputs.
+
+    file_map = {}
+    dest_dirs = set()
+
+    for f in source_files:
+        p = pathlib.PurePosixPath(f)
+
+        # Traverse the parent directories looking for an entry in the directory
+        # map. If we find an entry, apply the mapping. Otherwise we drop this
+        # file.
+        for d in p.parents:
+            if bytes(d) not in dir_map:
+                continue
+
+            # We have a map entry. Rewrite this path component to the new one
+            rel_path = p.relative_to(d)
+            dest_path = pathlib.PurePosixPath(dir_map[bytes(d)], rel_path)
+
+            file_map[p] = dest_path
+            dest_dirs.add(dest_path.parent)
+
+    # Nuke our destination directories to ensure they are pristine. This
+    # behavior could be configurable to do an overlay instead. We could also
+    # only sync if needed. But it is easier to just nuke and repave.
+
+    # If synchronizing to the root directory, we can't delete the root because
+    # it may have VCS directories. So handle it specially.
+    for p in sorted(dest_dirs):
+        rmtree_except_vcs(bytes(pathlib.Path(dest_base, p)))
+
+    for p in sorted(resolve_all_dirs(file_map.values()),
+                    key=lambda x: len(bytes(x))):
+        p = pathlib.Path(dest_base, p)
+        try:
+            p.mkdir()
+        except OSError as e:
+            if e.errno != errno.EEXIST:
+                raise
+
+    # And finally copy the file content over.
+    for source, dest in sorted(file_map.items()):
+        source = pathlib.Path(source_base, source)
+        dest = pathlib.Path(dest_base, dest)
+
+        shutil.copy2(bytes(source), bytes(dest))

--- a/vcssync/prod-requirements.txt
+++ b/vcssync/prod-requirements.txt
@@ -13,19 +13,25 @@ github3.py==0.9.6 \
     --hash=sha256:650d31dbc3f3290ea56b18cfd0e72e00bbbd6777436578865a7e45b496f09e4c
 
 kombu==3.0.37 \
     --hash=sha256:7ceab743e3e974f3e5736082e8cc514c009e254e646d6167342e0e192aee81a6
 
 Mercurial==4.2.3 \
     --hash=sha256:04908fc7d89e5810edf3d2762f5aecce5b5c0cb8534f3dbff7d0d848d11ff7ac
 
+pathlib2==2.3.0 \
+    --hash=sha256:db3e43032d23787d3e9aec8c7ef1e0d2c3c589d5f303477661ebda2ca6d4bfba
+
 python-hglib==1.7 \
     --hash=sha256:0dc087d15b774cda82d3c8096fb0e514caeb2ddb60eed38e9056b16e279ba3c5
 
 requests==2.13.0 \
     --hash=sha256:1a720e8862a41aa22e339373b526f508ef0c8988baf48b84d3fc891a8e237efb
 
+scandir==1.5 \
+    --hash=sha256:c2612d1a487d80fb4701b4a91ca1b8f8a695b1ae820570815e85e8c8b23f1283
+
 uritemplate==3.0.0 \
     --hash=sha256:1b9c467a940ce9fb9f50df819e8ddd14696f89b9a8cc87ac77952ba416e0a8fd
 
 uritemplate.py==3.0.2 \
     --hash=sha256:a0c459569e80678c473175666e0d1b3af5bc9a13f84463ec74f808f3dd12ca47

--- a/vcssync/setup.py
+++ b/vcssync/setup.py
@@ -10,16 +10,18 @@ console_scripts = [
     'servo-pulse-listen=mozvcssync.servo:pulse_daemon',
     'test-apply-changes=mozvcssync.util:test_apply_changes_from_list',
 ]
 
 # These commands are really only useful for testing. So don't expose them by
 # default.
 if 'VCSSYNC_ENABLE_TESTING_COMMANDS' in os.environ:
     console_scripts.extend([
+        'test-synchronize-directories=mozvcssync.cli:test_synchronize_directories',
+        'test-copy-workdir-git-to-hg=mozvcssync.cli:test_copy_workdir_git_to_hg',
     ])
 
 # ansible/roles/vcs-sync/defaults/main.yml must be updated if this package's
 # version number is changed.
 
 setup(
     name='mozvcssync',
     version='0.1',

new file mode 100644
--- /dev/null
+++ b/vcssync/tests/test-copy-workdir-git-to-hg.t
@@ -0,0 +1,170 @@
+  $ . $TESTDIR/vcssync/tests/helpers.sh
+
+Invalid source repository
+
+  $ mkdir bad-source
+  $ test-copy-workdir-git-to-hg bad-source irrelevant
+  fatal: Not a git repository (or any of the parent directories): .git
+  CalledProcessError: Command '['git', 'ls-files', '-z']' returned non-zero exit status 128
+  [1]
+
+Populate Git repository
+
+  $ git init source0
+  Initialized empty Git repository in $TESTTMP/source0/.git/
+  $ cd source0
+  $ echo file0 > file0
+  $ git add file0
+  $ git commit -m initial
+  [master (root-commit) aec8d6b] initial
+   1 file changed, 1 insertion(+)
+   create mode 100644 file0
+
+  $ mkdir -p dir0/subdir0 dir0/subdir1 dir2 dir3/subdir2/subsubdir0
+  $ echo file1 > dir0/file1
+  $ echo file2 > dir0/subdir0/file2
+  $ echo file3 > dir0/subdir0/file3
+  $ echo file4 > dir0/subdir1/file4
+  $ echo file5 > dir2/file5
+  $ echo file6 > dir3/subdir2/subsubdir0/file6
+
+  $ git add -A
+  $ git commit -m 'add more files'
+  [master c02e407] add more files
+   6 files changed, 6 insertions(+)
+   create mode 100644 dir0/file1
+   create mode 100644 dir0/subdir0/file2
+   create mode 100644 dir0/subdir0/file3
+   create mode 100644 dir0/subdir1/file4
+   create mode 100644 dir2/file5
+   create mode 100644 dir3/subdir2/subsubdir0/file6
+
+  $ touch ignored dir0/ignored dir2/ignored
+  $ cat > .gitignore << EOF
+  > ignored
+  > EOF
+  $ git add .gitignore
+  $ git commit -m 'add ignore rules'
+  [master 837b388] add ignore rules
+   1 file changed, 1 insertion(+)
+   create mode 100644 .gitignore
+
+  $ cd ..
+
+Invalid destination repository
+
+  $ mkdir bad-dest
+  $ test-copy-workdir-git-to-hg source0 bad-dest
+  ServerError: 
+  [1]
+
+Full synchronization works
+
+  $ hg init empty-dest
+  $ test-copy-workdir-git-to-hg source0 empty-dest
+
+  $ hg -R empty-dest status
+  A .gitignore
+  A dir0/file1
+  A dir0/subdir0/file2
+  A dir0/subdir0/file3
+  A dir0/subdir1/file4
+  A dir2/file5
+  A dir3/subdir2/subsubdir0/file6
+  A file0
+
+Synchronizing a specific directory works
+
+  $ hg init rename-directory
+  $ test-copy-workdir-git-to-hg source0 rename-directory --map dir0:renamed
+
+  $ hg -R rename-directory status
+  A renamed/file1
+  A renamed/subdir0/file2
+  A renamed/subdir0/file3
+  A renamed/subdir1/file4
+
+Synchronizing a sub-directory to the root directory works
+
+  $ hg init subdir-to-root
+  $ test-copy-workdir-git-to-hg source0 subdir-to-root --map dir0:.
+
+  $ hg -R subdir-to-root status
+  A file1
+  A subdir0/file2
+  A subdir0/file3
+  A subdir1/file4
+
+Moving entire repository to a sub-directory works
+
+  $ hg init root-to-subdir
+  $ test-copy-workdir-git-to-hg source0 root-to-subdir --map .:newparent
+
+  $ hg -R root-to-subdir status
+  A newparent/.gitignore
+  A newparent/dir0/file1
+  A newparent/dir0/subdir0/file2
+  A newparent/dir0/subdir0/file3
+  A newparent/dir0/subdir1/file4
+  A newparent/dir2/file5
+  A newparent/dir3/subdir2/subsubdir0/file6
+  A newparent/file0
+
+Extra files in dest are scheduled for deletion
+
+  $ hg init extra-files
+  $ cd extra-files
+  $ mkdir -p dir0/subdir0
+  $ touch dir0/extra-file dir0/subdir0/extra-file
+  $ hg -q commit -A -m initial
+  $ cd ..
+
+  $ test-copy-workdir-git-to-hg source0 extra-files --map dir0:dir0
+  $ hg -R extra-files status
+  A dir0/file1
+  A dir0/subdir0/file2
+  A dir0/subdir0/file3
+  A dir0/subdir1/file4
+  R dir0/extra-file
+  R dir0/subdir0/extra-file
+
+Rename detection works
+
+  $ git clone source0 source-rename
+  Cloning into 'source-rename'...
+  done.
+  $ hg init rename-detection
+  $ test-copy-workdir-git-to-hg source-rename rename-detection
+  $ hg -R rename-detection commit -m initial
+
+  $ cd source-rename
+  $ git mv dir0 dir0-renamed
+  $ git mv dir2/file5 dir2/file5-renamed
+  $ git commit -m 'perform renames'
+  [master 5ba3017] perform renames
+   5 files changed, 0 insertions(+), 0 deletions(-)
+   rename {dir0 => dir0-renamed}/file1 (100%)
+   rename {dir0 => dir0-renamed}/subdir0/file2 (100%)
+   rename {dir0 => dir0-renamed}/subdir0/file3 (100%)
+   rename {dir0 => dir0-renamed}/subdir1/file4 (100%)
+   rename dir2/{file5 => file5-renamed} (100%)
+  $ cd ..
+
+  $ test-copy-workdir-git-to-hg source-rename rename-detection
+
+  $ hg -R rename-detection status --copies
+  A dir0-renamed/file1
+    dir0/file1
+  A dir0-renamed/subdir0/file2
+    dir0/subdir0/file2
+  A dir0-renamed/subdir0/file3
+    dir0/subdir0/file3
+  A dir0-renamed/subdir1/file4
+    dir0/subdir1/file4
+  A dir2/file5-renamed
+    dir2/file5
+  R dir0/file1
+  R dir0/subdir0/file2
+  R dir0/subdir0/file3
+  R dir0/subdir1/file4
+  R dir2/file5

new file mode 100644
--- /dev/null
+++ b/vcssync/tests/test-synchronize-directories.t
@@ -0,0 +1,323 @@
+  $ . $TESTDIR/vcssync/tests/helpers.sh
+
+Create a test source directory tree
+
+  $ mkdir source0
+  $ cd source0
+  $ mkdir -p dir0/subdir0 dir0/subdir1 dir0/subdir2 dir1/subdir3 dir1/subdir4 dir2 dir3/subdir5/subsubdir0
+  $ echo file0 > file0
+  $ echo file1 > dir0/file1
+  $ echo file2 > dir0/file2
+  $ chmod +x dir0/file2
+  $ echo file3 > dir0/subdir0/file3
+  $ echo file4 > dir0/subdir1/file4
+  $ echo file5 > dir0/subdir2/file5
+  $ echo file6 > dir0/subdir2/file6
+  $ echo file7 > dir1/subdir4/file7
+  $ echo file8 > dir2/file8
+  $ echo file9 > dir3/subdir5/subsubdir0/file9
+
+  $ cd ..
+
+A full synchronization to empty dest works
+
+  $ mkdir dest-full
+  $ test-synchronize-directories source0 dest-full
+
+  $ find dest-full | sort
+  dest-full
+  dest-full/dir0
+  dest-full/dir0/file1
+  dest-full/dir0/file2
+  dest-full/dir0/subdir0
+  dest-full/dir0/subdir0/file3
+  dest-full/dir0/subdir1
+  dest-full/dir0/subdir1/file4
+  dest-full/dir0/subdir2
+  dest-full/dir0/subdir2/file5
+  dest-full/dir0/subdir2/file6
+  dest-full/dir1
+  dest-full/dir1/subdir4
+  dest-full/dir1/subdir4/file7
+  dest-full/dir2
+  dest-full/dir2/file8
+  dest-full/dir3
+  dest-full/dir3/subdir5
+  dest-full/dir3/subdir5/subsubdir0
+  dest-full/dir3/subdir5/subsubdir0/file9
+  dest-full/file0
+
+Synchronization to hg repo doesn't delete .hg/
+
+  $ hg init dest-hg
+  $ test-synchronize-directories source0 dest-hg
+  $ find dest-hg | sort
+  dest-hg
+  dest-hg/.hg
+  dest-hg/.hg/00changelog.i
+  dest-hg/.hg/requires
+  dest-hg/.hg/store
+  dest-hg/dir0
+  dest-hg/dir0/file1
+  dest-hg/dir0/file2
+  dest-hg/dir0/subdir0
+  dest-hg/dir0/subdir0/file3
+  dest-hg/dir0/subdir1
+  dest-hg/dir0/subdir1/file4
+  dest-hg/dir0/subdir2
+  dest-hg/dir0/subdir2/file5
+  dest-hg/dir0/subdir2/file6
+  dest-hg/dir1
+  dest-hg/dir1/subdir4
+  dest-hg/dir1/subdir4/file7
+  dest-hg/dir2
+  dest-hg/dir2/file8
+  dest-hg/dir3
+  dest-hg/dir3/subdir5
+  dest-hg/dir3/subdir5/subsubdir0
+  dest-hg/dir3/subdir5/subsubdir0/file9
+  dest-hg/file0
+
+Synchronization to git repo doesn't delete .git/
+
+  $ git init dest-git
+  Initialized empty Git repository in $TESTTMP/dest-git/.git/
+  $ test-synchronize-directories source0 dest-git
+  $ find dest-git -maxdepth 2 | sort
+  dest-git
+  dest-git/.git
+  dest-git/.git/HEAD
+  dest-git/.git/branches
+  dest-git/.git/config
+  dest-git/.git/description
+  dest-git/.git/hooks
+  dest-git/.git/info
+  dest-git/.git/objects
+  dest-git/.git/refs
+  dest-git/dir0
+  dest-git/dir0/file1
+  dest-git/dir0/file2
+  dest-git/dir0/subdir0
+  dest-git/dir0/subdir1
+  dest-git/dir0/subdir2
+  dest-git/dir1
+  dest-git/dir1/subdir4
+  dest-git/dir2
+  dest-git/dir2/file8
+  dest-git/dir3
+  dest-git/dir3/subdir5
+  dest-git/file0
+
+Executable bit is preserved
+
+  $ test -x dest-full/dir0/file2
+
+Extra files in dest should be removed
+
+  $ mkdir -p dest-populated/dir0 dest-populated/dir0/subdir-extra dest-populated/dir-extra
+  $ echo extra > dest-populated/dir0/file-extra
+  $ echo extra > dest-populated/dir0/subdir-extra/file-extra
+  $ echo extra > dest-populated/dir-extra/file-extra
+
+  $ test-synchronize-directories source0 dest-populated
+
+  $ find dest-populated | sort
+  dest-populated
+  dest-populated/dir0
+  dest-populated/dir0/file1
+  dest-populated/dir0/file2
+  dest-populated/dir0/subdir0
+  dest-populated/dir0/subdir0/file3
+  dest-populated/dir0/subdir1
+  dest-populated/dir0/subdir1/file4
+  dest-populated/dir0/subdir2
+  dest-populated/dir0/subdir2/file5
+  dest-populated/dir0/subdir2/file6
+  dest-populated/dir1
+  dest-populated/dir1/subdir4
+  dest-populated/dir1/subdir4/file7
+  dest-populated/dir2
+  dest-populated/dir2/file8
+  dest-populated/dir3
+  dest-populated/dir3/subdir5
+  dest-populated/dir3/subdir5/subsubdir0
+  dest-populated/dir3/subdir5/subsubdir0/file9
+  dest-populated/file0
+
+Existing file content should be replaced by source content
+
+  $ mkdir -p dest-content/dir0 dest-content/dir0/subdir0
+  $ echo file1-modified > dest-content/dir0/file1
+  $ echo file3-modified > dest-content/dir0/subdir0/file3
+
+  $ test-synchronize-directories source0 dest-content
+
+  $ find dest-populated -type f | sort
+  dest-populated/dir0/file1
+  dest-populated/dir0/file2
+  dest-populated/dir0/subdir0/file3
+  dest-populated/dir0/subdir1/file4
+  dest-populated/dir0/subdir2/file5
+  dest-populated/dir0/subdir2/file6
+  dest-populated/dir1/subdir4/file7
+  dest-populated/dir2/file8
+  dest-populated/dir3/subdir5/subsubdir0/file9
+  dest-populated/file0
+
+  $ cat dest-content/dir0/file1
+  file1
+  $ cat dest-content/dir0/subdir0/file3
+  file3
+
+Executable bit should be cleared or set as appropriate
+
+  $ mkdir -p dest-executable/dir0
+  $ echo file1 > dest-executable/dir0/file1
+  $ chmod +x dest-executable/dir0/file1
+  $ echo file2 > dest-executable/dir0/file2
+
+  $ test-synchronize-directories source0 dest-executable
+  $ find dest-executable -type f | sort
+  dest-executable/dir0/file1
+  dest-executable/dir0/file2
+  dest-executable/dir0/subdir0/file3
+  dest-executable/dir0/subdir1/file4
+  dest-executable/dir0/subdir2/file5
+  dest-executable/dir0/subdir2/file6
+  dest-executable/dir1/subdir4/file7
+  dest-executable/dir2/file8
+  dest-executable/dir3/subdir5/subsubdir0/file9
+  dest-executable/file0
+
+  $ test -x dest-executable/dir0/file1
+  [1]
+  $ test -x dest-executable/dir0/file2
+
+Attempt to map multiple sources to same dest files
+
+  $ test-synchronize-directories source0 dest-bad --map dir0:same-dir --map dir1:same-dir
+  ValueError: cannot map multiple inputs to same output
+  [1]
+
+Only synchronize a sub-directory to the same sub-directory
+
+  $ mkdir dest-dir0
+  $ test-synchronize-directories source0 dest-dir0 --map dir0:dir0
+
+  $ find dest-dir0 | sort
+  dest-dir0
+  dest-dir0/dir0
+  dest-dir0/dir0/file1
+  dest-dir0/dir0/file2
+  dest-dir0/dir0/subdir0
+  dest-dir0/dir0/subdir0/file3
+  dest-dir0/dir0/subdir1
+  dest-dir0/dir0/subdir1/file4
+  dest-dir0/dir0/subdir2
+  dest-dir0/dir0/subdir2/file5
+  dest-dir0/dir0/subdir2/file6
+
+Synchronize multiple sibling directories
+
+  $ mkdir dest-siblingdirs
+  $ test-synchronize-directories source0 dest-siblingdirs --map dir0/subdir0:dir0/subdir0 --map dir0/subdir1:dir0/subdir1
+
+  $ find dest-siblingdirs | sort
+  dest-siblingdirs
+  dest-siblingdirs/dir0
+  dest-siblingdirs/dir0/subdir0
+  dest-siblingdirs/dir0/subdir0/file3
+  dest-siblingdirs/dir0/subdir1
+  dest-siblingdirs/dir0/subdir1/file4
+
+Move a directory to the root
+
+  $ mkdir dest-move-to-root
+  $ test-synchronize-directories source0 dest-move-to-root --map dir0:.
+
+  $ find dest-move-to-root | sort
+  dest-move-to-root
+  dest-move-to-root/file1
+  dest-move-to-root/file2
+  dest-move-to-root/subdir0
+  dest-move-to-root/subdir0/file3
+  dest-move-to-root/subdir1
+  dest-move-to-root/subdir1/file4
+  dest-move-to-root/subdir2
+  dest-move-to-root/subdir2/file5
+  dest-move-to-root/subdir2/file6
+
+Executable bit should be preserved
+
+  $ test -x dest-move-to-root/file2
+
+Move the root to a sub-directory
+
+  $ mkdir dest-move-to-child
+  $ test-synchronize-directories source0 dest-move-to-child --map .:newparent
+
+  $ find dest-move-to-child | sort
+  dest-move-to-child
+  dest-move-to-child/newparent
+  dest-move-to-child/newparent/dir0
+  dest-move-to-child/newparent/dir0/file1
+  dest-move-to-child/newparent/dir0/file2
+  dest-move-to-child/newparent/dir0/subdir0
+  dest-move-to-child/newparent/dir0/subdir0/file3
+  dest-move-to-child/newparent/dir0/subdir1
+  dest-move-to-child/newparent/dir0/subdir1/file4
+  dest-move-to-child/newparent/dir0/subdir2
+  dest-move-to-child/newparent/dir0/subdir2/file5
+  dest-move-to-child/newparent/dir0/subdir2/file6
+  dest-move-to-child/newparent/dir1
+  dest-move-to-child/newparent/dir1/subdir4
+  dest-move-to-child/newparent/dir1/subdir4/file7
+  dest-move-to-child/newparent/dir2
+  dest-move-to-child/newparent/dir2/file8
+  dest-move-to-child/newparent/dir3
+  dest-move-to-child/newparent/dir3/subdir5
+  dest-move-to-child/newparent/dir3/subdir5/subsubdir0
+  dest-move-to-child/newparent/dir3/subdir5/subsubdir0/file9
+  dest-move-to-child/newparent/file0
+
+Move multiple directories to different directories
+
+  $ mkdir dest-move-multiple
+  $ test-synchronize-directories source0 dest-move-multiple --map dir0:dir0-rewrite --map dir3:newparent/dir3-rewrite
+
+  $ find dest-move-multiple | sort
+  dest-move-multiple
+  dest-move-multiple/dir0-rewrite
+  dest-move-multiple/dir0-rewrite/file1
+  dest-move-multiple/dir0-rewrite/file2
+  dest-move-multiple/dir0-rewrite/subdir0
+  dest-move-multiple/dir0-rewrite/subdir0/file3
+  dest-move-multiple/dir0-rewrite/subdir1
+  dest-move-multiple/dir0-rewrite/subdir1/file4
+  dest-move-multiple/dir0-rewrite/subdir2
+  dest-move-multiple/dir0-rewrite/subdir2/file5
+  dest-move-multiple/dir0-rewrite/subdir2/file6
+  dest-move-multiple/newparent
+  dest-move-multiple/newparent/dir3-rewrite
+  dest-move-multiple/newparent/dir3-rewrite/subdir5
+  dest-move-multiple/newparent/dir3-rewrite/subdir5/subsubdir0
+  dest-move-multiple/newparent/dir3-rewrite/subdir5/subsubdir0/file9
+
+When using directory map, extra files in mapped directories should be removed.
+Extra files elsewhere should be preserved.
+
+  $ mkdir -p dest-map-extra-files/dir1 dest-map-extra-files/extra-dir
+  $ touch dest-map-extra-files/extra-file
+  $ touch dest-map-extra-files/extra-dir/extra-file
+  $ touch dest-map-extra-files/dir1/extra-file
+  $ test-synchronize-directories source0 dest-map-extra-files --map dir1:dir1
+
+  $ find dest-map-extra-files | sort
+  dest-map-extra-files
+  dest-map-extra-files/dir1
+  dest-map-extra-files/dir1/extra-file
+  dest-map-extra-files/dir1/subdir4
+  dest-map-extra-files/dir1/subdir4/file7
+  dest-map-extra-files/extra-dir
+  dest-map-extra-files/extra-dir/extra-file
+  dest-map-extra-files/extra-file