Sometimes when writing Ruby tests with RSpec we want to run the whole test suite. Other times, we want to run only specific tests. Here are a few different ways to only run part of a test suite: --fail-fast flag
Running a spec file or full test suite with the --fail-fast flag will stop the tests at the first failure. For example: rspec spec --fail-fast will complete fully only if there are no failures in the suite. This can be helpful for large suites. --example (-e) flag
The --example (or -e) flag takes a string argument and runs only examples whose names include the argument. For example, if we had this spec file spec/example_spec.rb: RSpec.describe Example do
it "runs this specific test" do
...
end
it "does not run this" do
...
end
end
We can run rspec spec/example_spec.rb -e "specific test" and only the first test will run. This is an additional reason it can be helpful to have well described tests. :<line_number> flag
We can run an example on a specific line by including that line number right after the specific file when running the test. We can add line numbers to our previous example to clarify: 1 RSpec.describe Example do
2 it "runs this specific test" do
3 ...
4 end
5
6 it "does not run this" do
7 ...
8 end
9 end
We can run rspec spec/example_spec.rb:2 to only run the first spec. :focusIf we only want to run a specific context or example, we can add the following to our spec/spec_helper.rb to configure the ability to focus on a specific set of tests: RSpec.configure do |config|
config.filter_run focus: true
end
and then pass the symbol :focus as an optional argument to our example or group before running our tests: describe "only testing this", :focus do
...
end
Hopefully some of these methods of running specific tests are useful in avoiding running the full suite unnecessarily! | 
