Stop RSpec on the first failure with the -​-fail-fast command line option

When running a project’s RSpec test suite locally, have RSpec automatically stop on the first test failure with the --fail-fast command-line option¹.

bundle exec rspec --fail-fast

...............................F

Failures:

  1) Example divides the dividend by the divisor
     Failure/Error: expect(dividend / divisor).to eq(21)

     TypeError:
       nil can't be coerced into Integer
     # ./example_spec.rb:12:in `/'
     # ./example_spec.rb:12:in `block (3 levels) in <top (required)>'

Finished in 0.00507 seconds (files took 0.09149 seconds to load)
32 examples, 1 failure

Failed examples:

rspec './example_spec.rb[1:32]' # Example divides the dividend by the divisor

Aborting on the first failure saves time and reduces the amount of output printed to the screen when there are multiple failures in the run. For projects with slower test suites, turn use the --fail-fast option any time the suite runs locally, and save the full runs for CI.

1. Although the project-wide fail_fast configuration option² existed in earlier versions, the --fail-fast command line option was released as part of RSpec 2.1.

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2. To turn on --fail-fast for every tun, turn on the project-wide configuration option:

   RSpec.configure { |config| config.fail_fast = true }
   

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