Test from Dockerfile too

Author: impredicative

Dockerfile

@@ -1,4 +1,4 @@
-FROM python:3.8-slim-buster
+FROM python:3.8-slim-buster as build
 # python:3.7-slim-stretch (using Debian 9) has fewer issues with invalid https certificiates than python:3.7-slim-buster (using Debian 10).
 # As of 2019-11-29, python:3.8-slim-stretch doesn't exist. See https://github.com/docker-library/python/issues/428
 WORKDIR /app
@@ -15,3 +15,13 @@ USER app
 ENTRYPOINT ["python", "-m", "ircurltitlebot"]
 CMD ["--config-path", "/config/config.yaml"]
 STOPSIGNAL SIGINT
+
+FROM build as test
+WORKDIR /app
+USER root
+COPY pylintrc pyproject.toml requirements-dev.in setup.cfg vulture.txt ./
+COPY scripts/test.sh ./scripts/test.sh
+RUN pip install --no-cache-dir -Ur requirements-dev.in && \
+    ./scripts/test.sh
+
+FROM build

scripts/docker_build.sh

@@ -0,0 +1,11 @@
+#!/usr/bin/env bash
+# This script builds a containerized image. It can be run locally or in a remote CI workflow.
+set -euxo pipefail
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null 2>&1 && pwd )"
+cd "${DIR}"/..
+
+BASEDIR="${PWD##*/}"
+IMAGE_NAME="${BASEDIR}"
+
+docker build -t "${IMAGE_NAME}" .
+docker images