![]() The only difference is that you can only have one subject, and it’s meant to be an instance of the main object you are testing. The let! method is non-lazy, so the object will be created before any tests are run. It would be best to avoid these side-effects, but if you can’t do that then use the let! method. This can make a difference if creating this object has side-effects, like creating database entries, or writing to a file. The object won’t be created until the first time you use it. One thing you should know about let is that it’s “lazy”. Now you can reuse calculator in all your tests under the same describe block. ![]() If you want to write many tests & reuse the same objects you can define these objects with let statements. You write the tests first, then let the tests guide you on what you need to do next. This is what we call test-driven development (TDD). The next task is to implement the method:įinished in 0.00315 seconds (files took 0.09083 seconds to load) This is exactly where you want to be at this point! Wrong number of arguments (given 1, expected 0)Įrrors are not something to be frustrated with.Īdd one method argument to the factorial_of method: I fix this by creating the factorial_of method: This is normal because we don’t have a Factorial class yet. Uninitialized constant Factorial (NameError) When you run this code (like a regular Ruby program) you’ll get this: Now if we want to write a factorial method, we have to find out some valid values online or by hand calculation.Įxpect(calculator.factorial_of(5)).to eq(120) Then you call the method you want to exercise to get its return value.įinally, you verify the result with an expectation (RSpec) or assertion (Minitest). The setup is where you create any objects that you need to create. This is the test name, plus a way to group together all the components of the test itself. Then you need to create a describe block to group all your tests together & to tell RSpec which class you are testing. This is the initial code for writing your first RSpec test. We are going to write a simple application that finds factorial numbers. To understand how RSpec works let’s go over an example step-by-step. Most job applications will appreciate your testing skills, increasing your chances of landing the job. Tests can help you uncover corner cases & document them. If you are writing some complex logic, then you want to make sure it’s working with many different inputs & not just with one example you came up with. It helps you make sure your code is producing the results you expect When you are doing TDD you get a feedback loop that tells you what to focus on next, useful if you get distracted easily. Your tests describe what your application should be doing. …having tests increases your confidence! It helps document your code If you don’t have a test suite then you don’t want to touch your code, because of the fear of something breaking… Here’s why: It builds a safety net against errors (especially useful for refactoring)
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