Tests: 8XXX used as default port range.

After the launch of the project, the testing infrastructure was shared with
nginx project in some cases. To avoid port overlap, a decision was made
to shift

Tests: 8XXX used as default port range.

After the launch of the project, the testing infrastructure was shared with
nginx project in some cases. To avoid port overlap, a decision was made
to shift the port range for Unit tests. This problem was resolved a long time
ago and is no longer relevant, so it is now safe to use port 8XXX range as the
default, as it is more appropriate for testing purposes.

show more ...

Tests: get rid of classes in test files.

Class usage came from the unittest framework and it was always redundant
after migration to the pytest. This commit removes classes from files
containing te

Tests: get rid of classes in test files.

Class usage came from the unittest framework and it was always redundant
after migration to the pytest. This commit removes classes from files
containing tests to make them more readable and understandable.

show more ...

Tests: prerequisites checking reworked.

Prerequisites check moved to the module level to simplify class structure.
Discovery and prerequisites checks functions moved to the separate files.
Introduce

Tests: prerequisites checking reworked.

Prerequisites check moved to the module level to simplify class structure.
Discovery and prerequisites checks functions moved to the separate files.
Introduced "require" fixture to provide per-test requirements check.

show more ...

Tests: added tests for basic statistics.