test: Change test isolation model to 'database per test' #220
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Add a `testutils` package containing a shared `TestMain` function and the `with*` functions used by tests in other packages. The `SharedTestMain` function creates a new postgres container. Each of the `with*` functions then creates a new database in that container for the purposes of the test.
Use the new `testutils.With*` functions in tests in all packages.
exekias
approved these changes
Jan 8, 2024
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Improve the reliability and performance of the test suite by moving the test isolation model from 'container per test' to 'database per test'.
The current test suite works well locally but is very flaky when run on Github Actions. The cause of the flakiness is the 'container per test' isolation model, under which each testcase in each test starts its own Postgres container. This model worked well initially but as the number of tests has increased the actions runner often fails to make available the required number of containers for such a large number of parallel tests.
This PR changes the isolation model to 'database per test'. Each package creates one Postgres container and then each testcase in each test creates a database within that container. This greatly reduces the number of simultaneous containers required, making the test suite faster and more reliable.
Each job in the test matrix sees a 60-70% reduction in duration and (anecdotally) far fewer failures with no failures observed in ~20 runs.