pg-temp

pg_temp

Provides a simple class for creating a temporary userland Postgres db server.

The TempDB() class constructor will set up the database server in a temporary directory. If any databases are specified they are created inside the newly created server. The class provides a cleanup() method for stopping the server and disposing of the temporary files.

The module also provides an init_temp_db() function for managing the TempDB class as a singleton. This is useful for scenarios where you want to import in more than one module, but ensure that they all use the same database (and that the server and database are only created once). For example, this is handy in unit test code where you want to be able to test a single file or use a test runner to run tests in multiple files with only a single database.

init_temp_db() also registers an atexit handler to cleanup the temp database when the process exits.

Examples:

Create a temporary server with a database called 'testdb':

from pg_temp import TempDB
temp_db = TempDB(databases=['testdb'])

# you can connect to this database using temp_db's pg_socket_dir
connection = psycopg2.connect(host=temp_db.pg_socket_dir, database='testdb')

# ... do stuff...

temp_db.cleanup()

Alternatively, useful in a test runner:

import pg_temp
temp_db = pg_temp.init_temp_db(databases=['testdb'])
# repeat above in multiple modules

# you can connect to this database using temp_db's pg_socket_dir
connection = psycopg2.connect(host=temp_db.pg_socket_dir, database='testdb')

# ... do stuff...
# the db is automatically cleaned up when the process exits

Last an interactive example:

>>> import pg_temp
>>> import psycopg2
>>> temp_db = pg_temp.TempDB(databases=['testdb'])
Creating temp PG server... done
(Connect on: `psql -h /var/folders/d7/n3_h9vnn3w3bbmsnbdb73fmw0000gn/T/pg_tmp_OQMGwC/socket`)
>>> connection = psycopg2.connect(host=temp_db.pg_socket_dir, database='testdb')
>>> cur = connection.cursor()
# The rest is stolen from psycopg's documentation.  You get the idea...
>>> cur.execute("CREATE TABLE test (id serial PRIMARY KEY, num integer, data varchar);")
>>> cur.execute("INSERT INTO test (num, data) VALUES (%s, %s)",
... (100, "abc'def"))
>>> cur.execute("SELECT * FROM test;")
>>> cur.fetchone()
(1, 100, "abc'def")
>>> connection.close()
>>> temp_db.cleanup()

Development

Install dependencies for testing:

# Create a virtualenv
virtualenv venv

# Activate the virtualenv
. venv/bin/activate

# Install dependencies for testing
pip install -r requirements-dev.txt

Run the unit tests directly:

make test

To test against multiple Python versions, without needing to use Virtualenv directly, run the unit tests using tox:

make tox

Check code style using flake8 and black:

make check

Code is auto-formatted using black. Since this was done relatively recently, you should configure git to ignore the reformatting commit using the --ignore-rev or the --ignore-revs-file option to git blame, or configure this by: git config blame.ignoreRevsFile .git-blame-ignore-revs The ignore revisions file is called .git-blame-ignore-revs