agent: Add AGENTS.md

Author: methane

AGENTS.md

@@ -0,0 +1,49 @@
+## Rule
+
+Do `ruff format` and `ruff check` before commit.
+
+## Running the MySQL test suite in this container
+
+1. Install the server and test dependencies if they are not already available:
+
+   ```sh
+   apt-get update
+   DEBIAN_FRONTEND=noninteractive apt-get install -y mysql-server
+   python -m pip install --upgrade -r requirements-dev.txt
+   ```
+
+2. Keep MySQL running in a separate, long-lived terminal/session. The container
+   does not run systemd, so start `mysqld` directly instead of using
+   `systemctl`:
+
+   ```sh
+   install -d -o mysql -g mysql /run/mysqld
+   rm -f /run/mysqld/mysqld.sock /run/mysqld/mysqld.sock.lock \
+     /run/mysqld/mysqlx.sock /run/mysqld/mysqlx.sock.lock \
+     /run/mysqld/mysqld.pid
+   mysqld --user=mysql --local-infile=1 \
+     --socket=/run/mysqld/mysqld.sock \
+     --pid-file=/run/mysqld/mysqld.pid
+   ```
+
+3. In another terminal/session, wait for MySQL and initialize a fresh data
+   directory. The SQL files create databases and users, so only run them when
+   `test1` does not exist:
+
+   ```sh
+   until mysqladmin ping --silent; do sleep 1; done
+   if ! mysql -NBe "SHOW DATABASES LIKE 'test1'" | rg -q '^test1$'; then
+     mysql -uroot --comments < ci/docker-entrypoint-initdb.d/init.sql
+     mysql -uroot --comments < ci/docker-entrypoint-initdb.d/mysql.sql
+     mysql -uroot --comments < ci/docker-entrypoint-initdb.d/mariadb.sql
+   fi
+   cp ci/docker.json pymysql/tests/databases.json
+   ```
+
+4. Run the same test commands as CI:
+
+   ```sh
+   pytest -v --cov --cov-config .coveragerc pymysql
+   pytest -v --cov-append --cov-config .coveragerc \
+     --doctest-modules pymysql/converters.py
+   ```