532918e13d
When creating a new branch, we copied all WAL from the source timeline to the new one, and it was being picked up and digested into the repository on first use of the timeline. Fix by copying the WAL only up to the branch's starting point. We should probably move the branch-creation code from the CLI to page server itself - that's what I was starting to hack on when I noticed this bug - but let's fix this first. Add a regression test. To test multiple branches, enhance the python test fixture to manage multiple running Postgres instances. Also, for convenience, add a function to the postgres fixture to open a connection to the server with psycopg2.
Zenith test runner
This directory contains integration tests.
Prerequisites:
- Python 3.6 or later
- Python packages: pytest, psycopg2
- pytest 6.0 is required.
- NOTE:
apt installon Debian/Ubuntu won't work. They ship a much older version of pytest (and sometimes rename it topytest-3.) - Install using something like this:
pip3 install pytest psycopg2(Debian or Ubuntu)
- Zenith and Postgres binaries
- See the root README.md for build directions
- Tests can be run from the git tree; or see the environment variables below to run from other directories.
- The zenith git repo, including the postgres submodule (for some tests, e.g. pg_regress)
Running the tests
Because pytest will search all subdirectories for tests, it's easiest to
run the tests from within the test_runner directory.
Test state (postgres data, pageserver state, and log files) will
be stored under a directory test_output.
You can run all the tests with:
pytest
If you want to run all the tests in a particular file:
pytest test_pgbench.py
If you want to run all tests that have the string "bench" in their names:
pytest -k bench
Useful environment variables:
ZENITH_BIN: The directory where zenith binaries can be found.
POSTGRES_BIN: The directory where postgres binaries can be found.
TEST_OUTPUT: Set the directory where test state and test output files
should go.
TEST_SHARED_FIXTURES: Try to re-use a single postgres and pageserver
for all the tests.
Let stdout and stderr go to the terminal instead of capturing them:
pytest -s ...
(Note many tests capture subprocess outputs separately, so this may not
show much.)
Exit after the first test failure:
pytest -x ...
(there are many more pytest options; run pytest -h to see them.)
Building new tests
The tests make heavy use of pytest fixtures. You can read about how they work here: https://docs.pytest.org/en/stable/fixture.html
Essentially, this means that each time you see a fixture named as an input parameter, the function with that name will be run and passed as a parameter to the function.
So this code:
def test_something(zenith_cli, pg_bin):
pass
... will run the fixtures called zenith_cli and pg_bin and deliver those results to the test function.
Fixtures can't be imported using the normal python syntax. Instead, use this:
pytest_plugins = ("fixtures.something")
That will make all the fixtures in the fixtures/something.py file available.
Anything that's likely to be used in multiple tests should be built into a fixture.
Note that fixtures can clean up after themselves if they use the yield syntax.
Cleanup will happen even if the test fails (raises an unhandled exception).
Python destructors, e.g. __del__() aren't recommended for cleanup.