3. Describe the Concepts of Test-Driven Development 200-901 Practice Questions (Page 9)

Questions 41–45

1. 41foundation · easy

   In the red-green-refactor cycle of test-driven development, what is the immediate next step after writing a new test that fails?

   • ADelete the test and write a different one
   • BRun all existing tests to confirm they still pass
   • CRefactor the existing code to improve its structure
   • DWrite the minimal amount of code needed to make the test pass
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2. 42expert · medium

   A developer is writing a test for a function that parses a Cisco IOS 'show version' output to extract the IOS version string. The function should return 'Version 15.2(4)M7' for a given input. The developer writes the test and runs it, but it fails because the function returns 'Version 15.2(4)M7 ' with a trailing space. What is the most appropriate action?

   • AChange the test to expect the trailing space
   • BRefactor the test to use a regex that matches both with and without space
   • CModify the function to strip trailing whitespace and re-run the test
   • DIgnore the failure because the trailing space is harmless
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4. 43expert · medium

   A team is considering adopting TDD for a legacy network automation codebase that has no existing tests. They are concerned about the effort required to retrofit tests. What is the most effective strategy?

   • ARewrite the entire codebase using TDD from scratch
   • BStart writing tests for new features and refactor existing code incrementally
   • CWrite tests for all existing code before adding new features
   • DAvoid TDD for legacy code and only use it for new projects
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5. 44expert · medium

   A developer is writing a unit test for a function that sends a configuration to a device via SSH and parses the output. The function uses a third-party SSH library. The developer wants to test the parsing logic without a real device. Which approach is most effective?

   • AUse a real SSH server in a container to test the function
   • BSkip testing the parsing logic because it is trivial
   • CMock the SSH library's exec_command method to return a predefined output string
   • DWrite a test that checks the function's source code for correct SSH usage
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6. 45expert · medium

   A developer has completed a TDD cycle for a new feature. The tests pass, but the code has a long method that mixes parsing and validation logic. The developer wants to improve maintainability. What is the best approach?

   • AAdd comments to explain the method's logic
   • BRewrite the tests to match the current method structure
   • CRefactor the method into smaller, focused methods and re-run the tests
   • DLeave the method as is because it works
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