I've written about test leaks before, they are a pernicious, hard to debug thing that must be avoided at all costs.
Today I got a weird failure on CI and while investigating, it became apparent that some other spec is leaving records in the test DB, working outside DB transaction.
I know of two common ways to sidestep transactionality:
- Creating records in a
before(:all)block. Sometimes this may be necessary to save on repeat setup time, but look into TestProf'sbefore_allhelper for a safer approach. - Creating records in inline code outside example context:
describe "#some_method" do
# the two users fabricated in this hash will leak.
{
regular: FactoryBot.create(:user),
elevated: FactoryBot.create(:super_user),
}.each_pair do |permission_level, record|
it "works for '#{#{permission_level}}'" do
# some asserts ...
end
end
end
To avoid cases like this in the future, I recommend setting up a simple hook that checks the test DB has no records of popular models used in your app.
Place in a file location that gets loaded by spec helper, usually spec/support/hooks/:
class RecordsLeftInTestDBError < StandardError; end
RSpec.configure do |config|
config.after(:suite) do
counts = {
some_records: SomeModel.count,
}
counts.values.sum.positive? &&
# I'd prefer `abort` to `raise`, but for some reason
# it does not fail the RSpec run when called from an
# after-suite hook like this.
raise(
RecordsLeftInTestDBError.new(
"Leak detected!\n" \
"Records in the test DB after running the suite:\n" \
"#{counts}",
),
)
end
end
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