ci: new regression test for the Python module

Signed-off-by: d9pouces <github@19pouces.net>

id_tools/test.py

@@ -0,0 +1,66 @@
+"""Utilities for the Docker integration tests under tests/."""
+
+from __future__ import annotations
+
+import os
+import pathlib
+from typing import Annotated
+
+import jinja2
+import typer
+
+app = typer.Typer(help="Utilities for the tests/ Docker integration tests")
+
+TESTS_DIR = pathlib.Path(__file__).resolve().parent.parent / "tests"
+
+
+def _env(name: str) -> str:
+    """Jinja2 filter: `'NAME' | env` -> the environment variable NAME."""
+    return os.environ[name]
+
+
+def _file(relative: str) -> str:
+    """Jinja2 filter: `'relative/path' | file` -> content of tests/relative/path."""
+    path = (TESTS_DIR / relative).resolve()
+    if path != TESTS_DIR and TESTS_DIR not in path.parents:
+        raise ValueError(f"refusing to read a file outside of {TESTS_DIR}: {relative}")
+    return path.read_text(encoding="utf-8")
+
+
+def render_template(text: str) -> str:
+    """Render a tests/configs/*.yaml.tmpl fixture as a Jinja2 template.
+
+    Custom filters: `| env` reads an environment variable, `| file` reads a
+    file relative to tests/. Combine with Jinja2's built-in `indent` filter
+    to fit multi-line content (e.g. a PEM certificate) into a YAML
+    block-literal field, e.g.:
+
+        content: |
+          {{ 'certs/test-ca.crt.pem' | file | indent(6, first=true) }}
+    """
+    # Autoescaping is for HTML output; these templates render YAML, so escaping
+    # would corrupt them (e.g. turning "&" into "&" inside a PEM/URL).
+    environment = jinja2.Environment(undefined=jinja2.StrictUndefined)  # nosec B701
+    environment.filters["env"] = _env
+    environment.filters["file"] = _file
+    return environment.from_string(text).render()
+
+
+@app.command(
+    name="render-config",
+    help="Render a tests/configs/*.yaml.tmpl fixture into a ready-to-use configuration.",
+)
+def render_config(
+    template: Annotated[pathlib.Path, typer.Argument(exists=True, dir_okay=False)],
+    output: pathlib.Path,
+) -> None:
+    """Renders `template` as a Jinja2 template (see `render_template`) and
+    writes the result to `output`, creating its parent directories as
+    needed."""
+    content = render_template(template.read_text(encoding="utf-8"))
+    output.parent.mkdir(parents=True, exist_ok=True)
+    output.write_text(content, encoding="utf-8")
+
+
+if __name__ == "__main__":
+    app()