RSpec Order-Dependent Failures - Fix Random-Order Flake in CI

By Daniel Zoghalchali·Latchkey

A spec passes in one order and fails in another because state leaks between examples. RSpec’s random ordering exposes it: data left in the DB, a mutated global, or a class variable carried across examples.

What this error means

CI fails with "Randomized with seed N" and an example that passes when run alone. Re-running with the same seed reproduces it; a different seed may hide it - the tell-tale of an order dependency.

Randomized with seed 51423

Failures:
  1) OrdersController GET index returns only this user's orders
     expected 2 orders, got 5
# passes alone; fails after another spec leaves orders behind

Common causes

Data not rolled back between examples

Records created in one example persist (no transactional fixtures, or a truncation strategy that did not run), so a later example sees unexpected rows.

Mutated global or class state

A class variable, constant, or global config changed in one example and not restored leaks into others depending on order.

How to fix it

Isolate database state per example

Use transactional fixtures or DatabaseCleaner so each example starts clean.

# rails_helper.rb
RSpec.configure do |config|
  config.use_transactional_fixtures = true
end

Reproduce with the seed and isolate

1. Re-run with the printed seed: rspec --seed 51423 to reproduce deterministically.
2. Bisect by running the failing example after suspected predecessors.
3. Restore any global/class state you mutate in an after hook.

How to prevent it

• Keep config.order = :random so coupling surfaces early.
• Use transactional fixtures or DatabaseCleaner consistently.
• Never share mutable global/class state across examples.

Frequently asked questions

Related guides

References

• GitHub Actions documentation