Test cases fails if parallelism is used, passes otherwise

Build Environment
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1

Mine is a Rails application using rspec for test cases.
When I try to run test cases in parallel containers they get failed but passes otherwise.
It was working fine earlier. “So, When did this all start?”

I just upgraded the neo4j gem version that wants migration to be to be written which were earlier part of the model definition.
After writing migration, and testing locally (test passes on my development machine), the code was pushed to circleci and the issue started appearing.
Neo4j Issuelink might be helpful for whats happening.
Don’t get confused with this comment as the test passed only in the case when executed in a single container.

Summary: Test cases fails only when run parallel else passes
Please help as building in single container takes a lot more time now.

2

Adding parallel: true flag solved the issue.

    test:
      pre:
        - rake neo4j:migrate:
            parallel: true

The problem I think is the circlelci UI that confuses the user, as the command looks like to have been executed on all containers but actually ran on only the first.