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PostgreSQL/JDBC Test Suite Howto

1 - Introduction

The PostgreSQL source tree contains an automated test suite for the JDBC driver. This document explains how to install, configure and run this test suite. Furthermore, it offers guidelines and an example for developers to add new test cases.

2 - Installation

Of course, you need to have a Java 8 JDK.

You need to install and build the PostgreSQL JDBC driver source tree. You can download it from https://github.com/pgjdbc/pgjdbc. See README in that project for more information.

In this Howto we'll use $JDBC_SRC to refer to the top-level directory of the JDBC driver source tree. The test suite is the directory where you cloned the https://github.com/pgjdbc/pgjdbc project from GitHub.

3 - Test PostgreSQL Database

The test suite requires a PostgreSQL database to run the tests against and a user to login as. The tests will create and drop many objects in this database, so it should not contain production tables to avoid loss of data. We recommend you assign the following names:

  • database: test

  • username: test

  • password: test

  • The test user must have CREATE privilege on the test database.

  • There must be a superuser named postgres.

  • The test user must have the REPLICATION attribute.

  • The test PostgreSQL instance must be started with wal_level = logical.

If you have chosen other names you need to create a file named $JDBC_SRC/build.local.properties and add your customized values of the properties database, username and password.

The test suite requires that you have the contrib/lo and contrib/test_decoding modules installed.

If you have Docker, you can use docker-compose to launch test database (see docker):

cd docker && bin/postgresql-server

Helper script to start a postgres container for testing the PGJDBC driver.

This is the same container used by the automated CI platform and can be used
to reproduce CI errors locally. It respects all the same environment variables
used by the CI matrix:

PGV   = "8.4" | "9.0" | ... "13" ...   - PostgreSQL server version (defaults to latest)
SSL   = "yes" | "no"                   - Whether to enable SSL
XA    = "yes" | "no"                   - Whether to enable XA for prepared transactions
SCRAM = "yes" | "no"                   - Whether to enable SCRAM authentication
TZ    = "Etc/UTC" | ...                - Override server timezone (default Etc/UTC)
CREATE_REPLICAS = "yes" | "no"         - Whether to create two streaming replicas (defaults to off)

The container is started in the foreground. It will remain running until it
is killed via Ctrl-C.

To start the default (latest) version:

docker/bin/postgres-server

To start a v8.4 server without SSL:

PGV=8.4 SSL=off docker/bin/postgres-server

To start a v10 server with SCRAM disabled:

 PGV=10 SCRAM=no docker/bin/postgres-server

To start a v11 server with a custom timezone:

PGV=11 TZ=Americas/New_York docker/bin/postgres-server

To start a v13 server with the defaults (SSL + XA + SCRAM):

PGV=13 docker/bin/postgres-server

To start the default (latest) version with read only replicas:

CREATE_REPLICAS=on docker/bin/postgres-server

An alternative way is to use a Vagrant script: jackdb/pgjdbc-test-vm. Follow the instructions on that project's README page.

4 - Running the test suite

$ cd $JDBC_SRC
$ ./gradlew test

This will run the command line version of JUnit. If you'd like to see an animated coloured progress bar as the tests are executed, you may want to use one of the GUI versions of the test runner. See the JUnit documentation for more information.

If the test suite reports errors or failures that you cannot explain, please post the relevant parts of the output to the mailing list pgsql-jdbc@postgresql.org.

5 - Extending the test suite with new tests

Most of the tests are written with JUnit4, however it is recommended to create new tests with JUnit5.

If you're not familiar with JUnit, we recommend that you first read the introductory article JUnit Test Infected: Programmers Love Writing Tests. Before continuing, you should ensure you understand the following concepts: test suite, test case, test, fixture, assertion, failure.

The test suite consists of test cases, which consist of tests. A test case is a collection of tests that test a particular feature. The test suite is a collection of test cases that together test the driver - and to an extent the PostgreSQL backend - as a whole.

If you decide to add a test to an existing test case, all you need to do is add a method with a name that begins with "test" and which takes no arguments. JUnit will dynamically find this method using reflection and run it when it runs the test case. In your test method you can use the fixture that is setup for it by the test case.

If you decide to add a new test case, you should do two things:

  1. Add a test class. It should contain setUp() and tearDown() methods that create and destroy the fixture respectively.
  2. Add your test class in $JDBC_SRC/src/test/java/org/postgresql/test. This will make the test case part of the test suite.

6 - Guidelines for developing new tests

Every test should create and drop its own tables. We suggest to consider database objects (e.g. tables) part of the fixture for the tests in the test case. The test should also succeed when a table by the same name already exists in the test database, e.g. by dropping the table before running the test (ignoring errors). The recommended pattern for creating and dropping tables can be found in the example in section 7 below.

Please note that JUnit provides several convenience methods to check for conditions. See the Assert class in the Javadoc documentation of JUnit, which is installed on your system. For example, you can compare two integers using Assert.assertEquals(int expected, int actual). This method will print both values in case of a failure.

To simply report a failure use Assert.fail().

The JUnit FAQ explains how to test for a thrown exception.

As a rule, the test suite should succeed. Any errors or failures

  • which may be caused by bugs in the JDBC driver, the backend or the test suite - should be fixed ASAP. Don't let a test fail just to make it clear that something needs to be fixed somewhere. That's what the TODO lists are for.

Add some comments to your tests to explain to others what it is you're testing. A long sequence of JDBC method calls and JUnit assertions can be hard to comprehend.

For example, in the comments you can explain where a certain test condition originates from. Is it a JDBC requirement, PostgreSQL behaviour or the intended implementation of a feature?

7 - Example

See BlobTest.java for an example of a unit test that creates test table, runs a test, and then drops the table. There are other tests in pgjdbc/src/test/java/org/postgresql which you can use an examples. Please add your own tests in this location.

8 - SSL tests

  • requires SSL to be turned on in the database postgresql.conf ssl=true
  • pg_hba.conf requires entries for hostssl, and hostnossl
  • contrib module sslinfo needs to be installed in the databases
  • databases certdb, hostdb, hostnossldb, hostssldb, and hostsslcertdb need to be created

10 - Credits and Feedback

The parts of this document describing the PostgreSQL test suite were originally written by Rene Pijlman. Liam Stewart contributed the section on the Sun JDBC 2 test suite.

Please send your questions about the JDBC test suites or suggestions for improvement to the pgsql-jdbc@postgresql.org mailing list.