add documentation for new pytest tests

docs/develop/Development-Environment.md

@@ -26,12 +26,14 @@ following packages should get you started:
 ## Prerequisites for testing and documentation
 
 The Nominatim test suite consists of behavioural tests (using behave) and
-unit tests (using PHPUnit). It has the following additional requirements:
+unit tests (using PHPUnit for PHP code and pytest for Python code).
+It has the following additional requirements:
 
 * [behave test framework](https://behave.readthedocs.io) >= 1.2.5
 * [phpunit](https://phpunit.de) >= 7.3
 * [PHP CodeSniffer](https://github.com/squizlabs/PHP_CodeSniffer)
-* [Pylint](https://pylint.org/)
+* [Pylint](https://pylint.org/) (2.6.0 is used for the CI)
+* [pytest](https://pytest.org)
 
 The documentation is built with mkdocs:
 
@@ -49,7 +51,7 @@ To install all necessary packages run:
 sudo apt install php-cgi phpunit php-codesniffer \
                  python3-pip python3-setuptools python3-dev pylint
 
-pip3 install --user behave mkdocs
+pip3 install --user behave mkdocs pytest
 ```
 
 The `mkdocs` executable will be located in `.local/bin`. You may have to add

docs/develop/Testing.md

@@ -21,14 +21,15 @@ This test directory is sturctured as follows:
   | +-  api        Tests for API endpoints (search, reverse, etc.)
   |
   +-   php         PHP unit tests
+  +-   python      Python unit tests
   +-   scenes      Geometry test data
   +-   testdb      Base data for generating API test database
 ```
 
 ## PHP Unit Tests (`test/php`)
 
-Unit tests can be found in the php/ directory. They test selected php functions.
+Unit tests for PHP code can be found in the `php/` directory. They test selected
-Very low coverage.
+PHP functions. Very low coverage.
 
 To execute the test suite run
 
@@ -36,11 +37,20 @@ To execute the test suite run
     UNIT_TEST_DSN='pgsql:dbname=nominatim_unit_tests' phpunit ../
 
 It will read phpunit.xml which points to the library, test path, bootstrap
-strip and set other parameters.
+strip and sets other parameters.
 
 It will use (and destroy) a local database 'nominatim_unit_tests'. You can set
 a different connection string with e.g. UNIT_TEST_DSN='pgsql:dbname=foo_unit_tests'.
 
+## Python Unit Tests (`test/python`)
+
+Unit tests for Python code can be found in the `python/` directory. The goal is
+to have complete coverage of the Python library in `nominatim`.
+
+To execute the tests run
+
+    pytest test/python
+
 ## BDD Functional Tests (`test/bdd`)
 
 Functional tests are written as BDD instructions. For more information on