pycsw uses pytest for managing its automated tests.

OGC API - Records

Tests for OGC API - Records are located in tests/unittests/test_oarec.py. They can be run as follows:

pytest tests/unittests/test_oarec.py


There are a number of test suites that perform mostly functional testing. These tests ensure that pycsw is compliant with the various supported standards. There is also a growing set of unit tests. These focus on smaller scope testing, in order to verify that individual bits of code are working as expected.

Tests can be run locally as part of the development cycle. They are also run on pycsw’s GitHub Actions continuous integration setup against all pushes and pull requests to the code repository.


In addition to pycsw’s own tests, all public releases are also tested via the OGC Compliance & Interoperability Testing & Evaluation Initiative (CITE). The pycsw wiki documents CITE testing procedures and status.

Functional test suites

Most of pycsw’s tests are functional tests. This means that each test case is based on the requirements mandated by the specifications of the various standards that pycsw implements. These tests focus on making sure that pycsw works as expected.

Suites for xml-based standards (CSW, ATOM, etc)

A number of different test suites exist under tests/functionaltests/suites. Each suite specifies the following structure:

  • A mandatory default.yml file with the pycsw configuration that must be used by the test suite;

  • A mandatory expected/ directory containing the expected results for each request;

  • An optional data/ directory that contains .xml files with testing data that is to be loaded into the suite’s database before running the tests. The presence of this directory and its contents have the following meaning for tests:

    • If data/ directory is present and contains files, they will be loaded into a new database for running the tests of the suite;

    • If data/ directory is present and does not contain any data files, a new empty database is used in the tests;

    • If data/ directory is absent, the suite will use a database populated with test data from the CITE suite.

  • An optional get/requests.txt file that holds request parameters used for making HTTP GET requests.

    Each line in the file must be formatted with the following scheme:


    For example:


    When tests are run, the test_id is used for naming each test and for finding the expected result.

  • An optional post/ directory that holds .xml files used for making HTTP POST requests

Test generation uses pytest’s pytest_generate_tests function. This function is implemented in tests/functionaltests/conftest.py. It provides an automatic parametrization of the tests/functionaltests/test_suites_functional:test_suites test. This parametrization causes the generation of a test for each of the GET and POST requests defined in a suite’s directory.

Suites for JSON-based standards (OGC API - Records, STAC API, etc)

These are implemented as simple pytest-based tests, for which no custom test generation function exists. They are simpler to generate - look into the implementation in tests/functionaltests/suites/oarec for examples.

Unit tests

pycsw also features unit tests. These deal with testing the expected behaviour of individual functions.

The usual implementation of unit tests is to import the function/method under test, run it with a set of known arguments and assert that the result matches the expected outcome.

Unit tests are defined in pycsw/tests/unittests/<module_name>.

pycsw’s unit tests are marked with the unit marker. This makes it easy to run them in isolation:

# running only the unit tests (not the functional ones)
py.test -m unit

Running tests

Since pycsw uses pytest, tests are run with the py.test runner. A basic test run can be made with:


This command will run all tests and report on the number of successes, failures and also the time it took to run them. The py.test command accepts several additional parameters that can be used in order to customize the execution of tests. Look into pytest’s invocation documentation for a more complete description. You can also get a description of the available parameters by running:

py.test --help

Running specific suites and test cases

py.test allows tagging tests with markers. These can be used to selectively run some tests. pycsw uses two markers:

  • unit - run only input tests

  • functional- run only functional tests

Markers can be specified by using the -m <marker_name> flag.

py.test -m functional  # run only functional tests

You can also use the -k <name_expression> flag to select which tests to run. Since each test’s name includes the suite name, http method and an identifier for the test, it is easy to run only certain tests.

py.test -k "apiso and GetRecords"  # run only tests from the apiso suite that have GetRecords in their name
py.test -k "post and GetRecords"  # run only tests that use HTTP POST and GetRecords in their name
py.test -k "not harvesting"  # run all tests except those from the harvesting suite

The -m and -k flags can be combined.

Exiting fast

The --exitfirst (or -x) flag can be used to stop the test runner immediately as soon as a test case fails.

py.test --exitfirst

Seeing more output

There are three main ways to get more output from running tests:

  • The --verbose (or -v) flag;

  • The --capture=no flag - Messages sent to stdout by a test are not suppressed;

  • The --pycsw-loglevel flag - Sets the log level of the pycsw instance under test. Set this value to debug in order to see all debug messages sent by pycsw while processing a request.

py.test --verbose
py.test --pycsw-loglevel=debug
py.test -v --capture=no --pycsw-loglevel=debug

Comparing xml-based suite results with difflib instead of XML c14n

Functional tests for XML-based suites compare results with their expected values by using XML canonicalisation - XML c14n. Alternatively, you can call py.test with the --functional-prefer-diffs flag. This will enable comparison based on Python’s difflib. Comparison is made on a line-by-line basis and in case of failure, a unified diff will be printed to standard output.

py.test -m functional -k 'harvesting' --functional-prefer-diffs

Saving test results for disk

The result of each XML-based suite test can be saved to disk by using the --functional-save-results-directory option. Each result file is named after the test identifier it has when running with pytest.

py.test -m functional -k 'not harvesting' --functional-save-results-directory=/tmp/pycsw-test-results

Test coverage

Use the –cov pycsw flag in order to see information on code coverage. It is possible to get output in a variety of formats.

py.test --cov pycsw

Specifying a timeout for tests

The –timeout <seconds> option can be used to specify that if a test takes more than <seconds> to run it is considered to have failed. Seconds can be a float, so it is possibe to specify sub-second timeouts

py.test --timeout=1.5

Linting with flake8

Use the –flake8 flag to also check if the code complies with Python’s style guide

py.test --flake8

Testing multiple Python versions

For testing multiple Python versions and configurations simultaneously you can use tox. pycsw includes a tox.ini file with a suitable configuration. It can be used to run tests against multiple Python versions and also multiple database backends. When running tox you can send arguments to the py.test runner by using the invocation tox <tox arguments> – <py.test arguments>. Examples:

# install tox on your system
sudo pip install tox

# run all tests on multiple Python versions against all databases,
# with default arguments

# run tests only with python3.7 and using sqlite as backend
tox -e py37 -sqlite

# run only csw30 suite tests with python3.7 and postgresql as backend
tox -e py37-postgresql -- -k 'csw30'

Web Testing

You can also use the pycsw tests via your web browser to perform sample requests against your pycsw install. The tests are is located in tests/. To generate the HTML page:

$ paver gen_tests_html

Then navigate to http://host/path/to/pycsw/tests/index.html.