Rails Adds SKIP_TEST_DATABASE_TRUNCATE Flag To Speed Up Multi Process Test Runs | Saeloun Blog

Rails truncates (clearing out) the tables in our test database before running tests to ensure that each test starts with a clean state, free from any data left over by previous tests.While this ensures test isolation, it can also introduce significant overhead with unnecessary truncation operations especially in applications with a large number of tables.For instance, imagine an application with 178 tables. If we are running tests across 24 processes, each process might perform truncation for each test, leading to thousands of truncation operations. This redundancy can add a considerable amount of time to our test suite.