Adds tox.ini and basic rock test

Adds the following tox targets: fmt, lint, pack, export-to-docker,
sanity, integration.

Adds basic rock test, checking that the expected files exist in the
rock, and checking the added executables outputs.

tests/test_rock.py

@@ -0,0 +1,62 @@
+# Copyright 2024 Canonical Ltd.
+# See LICENSE file for licensing details.
+
+import pathlib
+import subprocess
+
+import pytest
+import yaml
+
+ROCK_EXPECTED_FILES = [
+    "/install-cni.sh",
+    "/ip-control-loop",
+    "/whereabouts",
+]
+
+METADATA = yaml.safe_load(pathlib.Path("./rockcraft.yaml").read_text())
+# Assuming rock name is the same as application name.
+ROCK_NAME = METADATA["name"]
+VERSION = METADATA["version"]
+LOCAL_ROCK_IMAGE = f"{ROCK_NAME}:{VERSION}"
+
+
+def _run_in_docker(check_exit_code, *command):
+    return subprocess.run(
+        [
+            "docker",
+            "run",
+            "--rm",
+            "-i",
+            LOCAL_ROCK_IMAGE,
+            "exec",
+            *command,
+        ],
+        check=check_exit_code,
+        capture_output=True,
+    )
+
+
+@pytest.mark.abort_on_fail
+def test_rock():
+    """Test rock."""
+    # check rock filesystem
+    _run_in_docker(True, "ls", "-la", *ROCK_EXPECTED_FILES)
+
+    # check binary name and version.
+    process = _run_in_docker(True, f"/{ROCK_NAME}", "version")
+    output = process.stderr.decode("utf-8")
+    assert ROCK_NAME in output and VERSION in output
+
+    # check other binary. It expects KUBERNETES_SERVICE_HOST to be defined.
+    process = _run_in_docker(False, "/ip-control-loop")
+    output = process.stderr.decode("utf-8")
+    assert "KUBERNETES_SERVICE_HOST" in output
+
+    # check script. It expects serviceaccount token to exist.
+    process = _run_in_docker(False, "/install-cni.sh")
+    output = process.stderr.decode("utf-8")
+    expected_error = (
+        "cat: /var/run/secrets/kubernetes.io/serviceaccount/token: "
+        "No such file or directory"
+    )
+    assert expected_error == output.strip()

tox.ini

@@ -0,0 +1,92 @@
+# Copyright 2024 Canonical Ltd.
+# See LICENSE file for licensing details.
+
+[tox]
+skipsdist = True
+skip_missing_interpreters = True
+envlist = fmt, lint, pack, export-to-docker, sanity, integration
+
+[testenv]
+setenv =
+    PYTHONPATH={toxinidir}
+    PYTHONBREAKPOINT=ipdb.set_trace
+
+[testenv:fmt]
+description = Apply coding style standards to code
+deps =
+    black
+    isort
+commands =
+    isort {toxinidir}/tests
+    black {toxinidir}/tests
+
+[testenv:lint]
+description = Check code against coding style standards
+deps =
+    black
+    flake8
+    pep8-naming
+    isort
+commands =
+    flake8 tests
+    isort --check-only --diff {toxinidir}/tests
+    black --check --diff {toxinidir}/tests
+
+[testenv:pack]
+passenv = *
+allowlist_externals =
+    rockcraft
+commands =
+    rockcraft pack
+
+[testenv:export-to-docker]
+passenv = *
+allowlist_externals =
+    bash
+    skopeo
+    yq
+commands =
+    # export already packed rock to docker
+    bash -c 'NAME=$(yq -r .name rockcraft.yaml) && \
+             VERSION=$(yq -r .version rockcraft.yaml) && \
+             ARCH=$(yq -r ".platforms | keys | .[0]" rockcraft.yaml) && \
+             ROCK="$\{NAME\}_$\{VERSION\}_$\{ARCH\}.rock" && \
+             DOCKER_IMAGE=$NAME:$VERSION && \\
+             echo "Exporting $ROCK to docker as $DOCKER_IMAGE" && \
+             rockcraft.skopeo --insecure-policy copy oci-archive:$ROCK docker-daemon:$DOCKER_IMAGE'
+
+[testenv:sanity]
+passenv = *
+deps =
+    pytest
+    pyyaml
+allowlist_externals =
+    echo
+commands =
+    # run rock tests
+    pytest -v --tb native --show-capture=all --log-cli-level=INFO {posargs} {toxinidir}/tests
+
+[testenv:integration]
+passenv = *
+allowlist_externals =
+    echo
+    bash
+    git
+    rm
+    tox
+deps =
+    juju<4.0
+    pytest
+    pytest-operator
+    ops
+commands =
+    echo "WARNING: This is a placeholder test - no test is implemented here."
+
+[flake8]
+max-line-length = 120
+select = E,W,F,C,N
+# E231: missing whitespace after ':'
+# E231 excluded for false positives in strings and fstrings.
+ignore = W503,E231
+exclude = venv,.git,.tox,.tox_env,.venv,build,dist,*.egg_info
+show-source = true