diff --git a/swh/loader/mercurial/tests/data/build.py b/swh/loader/mercurial/tests/data/build.py
new file mode 100755
--- /dev/null
+++ b/swh/loader/mercurial/tests/data/build.py
@@ -0,0 +1,265 @@
+#!/usr/bin/env python
+# Copyright (C) 2020 The Software Heritage developers
+# See the AUTHORS file at the top-level directory of this distribution
+# License: GNU General Public License version 3, or any later version
+# See top-level LICENSE file for more information
+"""
+This build script purpose is to create example repositories from bash scripts
+and extract assertion data from them into json files.
+
+Advantages:
+
+ - the bash script documents the repository creation
+ - automating creation allow easy repository update
+ - automation extraction allow easier update of assertion data
+
+Create a new repository
+-----------------------
+
+First, create a bash script `myscript.sh` which will serve to create, update
+and document the repository.
+
+Here is a minimal working example:
+
+ #!/usr/bin/env bash
+
+ # Setup bash in strict mode
+ set -euo pipefail
+
+ # Allow direct call to call the script: `./myscript.sh repository-name`
+ if [ ! -z "$1" ]; then
+ HG_REPO="$1"
+ fi
+
+ # Prepare the repository
+ hg init "$HG_REPO"
+ cd "$HG_REPO"
+ cat > .hg/hgrc << EOL
+ [ui]
+ username = Full Name<full.name@domain.tld>
+ EOL
+
+ # Populate the repository
+ touch README.md
+ hg add README.md
+ hg commit -m "Add README"
+
+Then build the repository and the associated json file which containing
+the repository objects identities:
+
+ ./build.py json myscript.sh
+
+You should now have a `myscript.tgz` containing the repository
+and a `myscript.json` with the repository objects identities.
+
+Update a repository
+-------------------
+
+When there is a build script file:
+
+ Update the source `repository.sh` and run `./build.py json repository.sh`.
+ New `tgz` and `json` files will be produced.
+ The old files will be renamed.
+
+When There is no build script file:
+
+ Maybe consider not updating the repository and add a new one instead.
+
+ Otherwise, uncompress the `repository.tgz`, manually update the `repository`
+ and run `./build.py json repository`.
+ New `tgz` and `json` files will be produced.
+ The old files will be renamed.
+
+Extract json from existing repository
+-------------------------------------
+
+For existing repository without build scripts it is possible to extract
+the corresponding json file by running `./build.py json repository.tgz`
+"""
+
+import json
+import shutil
+import subprocess
+from datetime import datetime
+from pathlib import Path
+
+import click
+
+
+def abort(message):
+ """Abort the script with a message."""
+ click.echo(message, err=True)
+ click.get_current_context().abort()
+
+
+def backup(path: Path):
+ """Rename an existing path."""
+ click.echo(f"Creating backup of {path}")
+ now = datetime.now()
+ backup_path = path.with_suffix(f"{path.suffix}.bak.{now:%Y%m%d%H%M%S}")
+ path.rename(backup_path)
+ click.echo(f"Backup created: {str(backup_path)!r}")
+
+
+def _build_repository(script: str) -> Path:
+ """Build a repository from a bash script."""
+ script_path = Path(script).absolute()
+
+ if not script_path.exists():
+ abort(f"Path {script_path!r} does not exists.")
+
+ if script_path.suffix != ".sh":
+ abort(f"Wrong suffix: {script_path.suffix!r}. Expected: '.sh'")
+
+ repository_path = script_path.with_suffix("")
+
+ if repository_path.exists():
+ backup(repository_path)
+
+ click.echo(f"Running build script: {str(script_path)!r}")
+ subprocess.call(
+ ["bash", "-euo", "pipefail", script_path], env={"HG_REPO": str(repository_path)}
+ )
+
+ return repository_path
+
+
+def _build_json(source: str) -> Path:
+ if source.endswith(".tgz"):
+ archive_path = Path(source).absolute()
+ repository_path = archive_path.with_suffix("")
+
+ if repository_path.exists():
+ backup(repository_path)
+
+ subprocess.call(["tar", "-xf", archive_path], cwd=archive_path.parent)
+ elif source.endswith(".sh"):
+ repository_path = _build_repository(source)
+ else:
+ repository_path = Path(source).absolute()
+
+ click.echo(f"Extracting object identities: {str(repository_path)!r}")
+ output = subprocess.check_output(["swh-hg-identify", "all"], cwd=repository_path)
+ lines = output.decode().splitlines()
+
+ directory_swhids = []
+ revision_swhids = []
+ release_swhids = []
+
+ for line in lines:
+ uri, _ = line.split("\t")
+ _, _, swhid_type, swhid = uri.split(":")
+ if swhid_type == "dir":
+ directory_swhids.append(swhid)
+ elif swhid_type == "rev":
+ revision_swhids.append(swhid)
+ elif swhid_type == "rel":
+ release_swhids.append(swhid)
+ elif swhid_type == "snp":
+ snapshot_swhid = swhid
+ else:
+ abort(f"{line!r} unknown type {swhid_type!r}")
+
+ json_path = repository_path.with_suffix(".json")
+
+ if json_path.exists():
+ backup(json_path)
+
+ click.echo(f"Creating object identities file: {str(json_path)!r}")
+ json_path.write_text(
+ json.dumps(
+ {
+ "directories": directory_swhids,
+ "revisions": revision_swhids,
+ "releases": release_swhids,
+ "snapshot": snapshot_swhid,
+ }
+ )
+ )
+
+ return json_path
+
+
+@click.group(help=__doc__.split("\n\n")[0])
+def main():
+ pass
+
+
+@main.command()
+def man():
+ """Display script's manual."""
+ click.echo(__doc__)
+
+
+@main.command("repository")
+@click.argument("script")
+def build_repository(script: str):
+ """Build a repository.
+
+ SCRIPT must be is a bash script with a `.sh` suffix
+
+ The generated repository will have the same path minor the `.sh` suffix.
+
+ The script will be passed repository name as the `HG_REPO` environment variable.
+ """
+ _build_repository(script)
+
+
+@main.command("json")
+@click.argument("source")
+def build_json(source: str):
+ """Build a json file of object identities.
+
+ SOURCE can be a script as required by the `repository` command
+ (see repository --help), a repository archive, or an existing repository.
+
+ The produced file will have the source path with the `.json` suffix.
+ """
+ _build_json(source)
+
+
+@main.command("archive")
+@click.option(
+ "--clean", "-c", default=False, is_flag=True, help="Remove created artifacts",
+)
+@click.argument("source")
+def build_archive(source: str, clean: bool = False):
+ """Build a repository archive and is associated json file.
+
+ SOURCE can be a script as required by the `repository` command
+ (see repository --help), or an existing repository.
+
+ The produced archive will have the source path with the `.tgz` suffix.
+ The produced json file will have the source path with the `.json` suffix.
+ """
+ if source.endswith(".sh"):
+ repository_path = _build_repository(source)
+ else:
+ repository_path = Path(source).absolute()
+ if not (repository_path / ".hg").exists():
+ abort(f"{str(repository_path)!r} is not a Mercurial repository")
+
+ json_path = _build_json(str(repository_path))
+
+ archive_path = repository_path.with_suffix(".tgz")
+ if archive_path.exists():
+ backup(archive_path)
+
+ subprocess.call(
+ [
+ "tar",
+ "-cf",
+ archive_path.relative_to(archive_path.parent),
+ repository_path.relative_to(archive_path.parent),
+ json_path.relative_to(archive_path.parent),
+ ],
+ cwd=archive_path.parent,
+ )
+
+ if clean:
+ shutil.rmtree(repository_path)
+ json_path.unlink()
+
+
+if __name__ == "__main__":
+ main()