When two dynamic table tests referencing to the same table name run concurrently, the results of the tests will be incorrect, causing the tests to fail.
As the condition to trigger this bug is strict (two dynamic table tests must reference the same table name, and they must run concurrently), it's hard to reproduce this bug in the current test set.
I construct two mock test classes to reproduce this bug stably. The two test classes are the same except for their names. One of the test class is listed as follows:
To reproduce this bug, run
to run these two test classes concurrently, the bug will occur.
- In the current implementation, when a test class wants to use a SqlTestFactory, it will use SqlTestFactory.INSTANCE, so every class using this factory actually shares the same factory instance.
- catalogReader is a member of SqlTestFactory, so every class actually shares the same catalogReader.
- As root schema is stored in catalog reader, table is stored in root schema, and row type is stored in table, every class actually has access to the same row type instance.
- As dynamic table will modify row type if a column name it wants to use doesn't exist, two test cases running concurrently and using the same table name may read and modify the same row type instance, causing the result of the test to be incorrect, thus causing the failure of the test.
What I've done in this commit is to remove SqlTestFactory.INSTANCE, and let every test class use a new instance of the factory, so that we can solve the concurrent modification problem.