PostgreSQL testing utility. Both Python 2.7 and 3.3+ are supported.

To install testgres, run:

pip install testgres

We encourage you to use virtualenv for your testing environment.

Note: by default testgres runs initdb, pg_ctl, psql provided by PATH.

There are several ways to specify a custom postgres installation:

• export PG_CONFIG environment variable pointing to the pg_config executable;
• export PG_BIN environment variable pointing to the directory with executable files.

Example:

export PG_BIN=$HOME/pg_10/bin
python my_tests.py

By default, cleanup() removes all temporary files (DB files, logs etc) that were created by testgres' API methods. If you'd like to keep logs, execute configure_testgres(node_cleanup_full=False) before running any tests.

Note: context managers (aka with) call cleanup() automatically.

Nodes support python logging system, so if you have configured logging in your tests, you can use it to redirect postgres logs to yours.

To do that, just use use_logging argument:

node = testgres.get_new_node('master', use_logging=True)

You can find working configuration example for logging in tests/test_simple.py.

Here is an example of what you can do with testgres:

import testgres

with testgres.get_new_node('test') as node:
    node.init()  # run initdb
    node.start() # start PostgreSQL
    print(node.execute('postgres', 'select 1'))
    node.stop()  # stop PostgreSQL

Let's walk through the code. First, you create a new node using:

with testgres.get_new_node('master') as node:

or

with testgres.get_new_node('master', '/path/to/DB') as node:

where master is a node's name, not a DB's name. Name matters if you're testing something like replication. Function get_new_node() only creates directory structure in specified directory (or somewhere in '/tmp' if we did not specify base directory) for cluster. After that, we have to initialize the PostgreSQL cluster:

node.init()

This function runs initdb command and adds some basic configuration to postgresql.conf and pg_hba.conf files. Function init() accepts optional parameter allows_streaming which configures cluster for streaming replication (default is False). Now we are ready to start:

node.start()

Finally, our temporary cluster is able to process queries. There are four ways to run them:

The last one is the most powerful: you can use begin(isolation_level), commit() and rollback():

with node.connect() as con:
    con.begin('serializable')
    print(con.execute('select %s', 1))
    con.rollback()

To stop the server, run:

node.stop()

It's quite easy to create a backup and start a new replica:

with testgres.get_new_node('master') as master:
    master.init().start()
    with master.backup() as backup:
        replica = backup.spawn_replica('replica').start()
        replica.catchup()  # catch up with master
        print(replica.execute('postgres', 'select 1'))

Note: you could take a look at pg_pathman to get an idea of testgres' capabilities.

testgres also can help you to make benchmarks using pgbench from postgres installation:

with testgres.get_new_node('master') as master:
    master.init().start()
    p = master.pg_bench_init(scale=10).pgbench(options=['-T', '60'])
    p.wait()

Ildar Musin <i.musin(at)postgrespro.ru> Postgres Professional Ltd., Russia
Dmitry Ivanov <d.ivanov(at)postgrespro.ru> Postgres Professional Ltd., Russia
Ildus Kurbangaliev <i.kurbangaliev(at)postgrespro.ru> Postgres Professional Ltd., Russia
Yury Zhuravlev <stalkerg(at)gmail.com>