3. Describe the Concepts of Test-Driven Development 200-901 Practice Questions (Page 4)

Questions 16–20

1. 16application · medium

   After implementing a new feature using TDD, a developer notices that the code has duplicated logic and long methods. All tests pass. What should the developer do next?

   • ALeave the code as is because it works and tests pass
   • BDelete the duplicated code and rely on the tests to catch any issues
   • CRewrite the tests to match the current code structure
   • DRefactor the code to improve readability and maintainability, then re-run the tests
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2. 17foundation · easy

   In test-driven development, why are unit tests typically written before the implementation?

   • ATo satisfy a requirement from the project manager
   • BTo ensure the test suite runs quickly
   • CTo document the code for future maintenance
   • DTo define the expected behavior of the unit
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4. 18application · medium

   An engineer is writing unit tests for a function that retrieves interface status from a network device via SNMP. The function takes a device IP and community string. To test the function in isolation, what should the engineer do?

   • AUse a real lab device to verify the function works end-to-end
   • BMock the SNMP library call so the test does not contact a real device
   • CWrite a test that checks the function's output against a known device's output
   • DSkip testing the function because it depends on external hardware
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5. 19application · medium

   A developer is writing a unit test for a function that calculates the number of active interfaces on a device. The function calls an external API to get interface status. To ensure the test is a true unit test, what should the developer do?

   • AMock the external API so the function is tested with controlled data
   • BTest the function by calling the API and checking the response
   • CUse a real device to verify the function's output
   • DSkip the test because the function is too simple
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6. 20application · medium

   An engineer is writing unit tests for a function that calculates the subnet mask from a prefix length. The function is pure and has no external dependencies. What is the most important characteristic of these unit tests?

   • AThey should cover every possible prefix length from 0 to 32
   • BThey should be written after the function is fully implemented
   • CThey should run against a real network device to verify accuracy
   • DThey should be fast, deterministic, and test only the function's logic
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