Test Driven Development

Question 1

What is test driven development?

Answer 1

Test Driven Development (TDD) is a development model where the tests for a function / system are written first and then the code is written to match what is expected of a test.

After success of the test and code for the first requirement, we write another test case to fulfil another requirement and repeat the cycle.

Question 2

What are the advantages of test driven development?

Answer 2

• Since code is only added as needed to meet the requirement of the test, the solution tends to have only code required to solve the problem – minimizes redundant code.
  
  • Code tends to be refactored after new tests are added.
• The amount of code written in total can be greater than non TDD environments, but developers claim there is little requirement to use a debugger.
• Since a Test case is written first, it ensures the each code path has at least one test case. Better coverage.
• Modifications to the code in future will require a full set of test passes before the modification can be accepted.
  - We always have a set of regression tests.

Question 3

What is the test driven development cycle?

Answer 3

1. Add a test
2. Run all tests and see if the new one fails
3. Write some code
4. Run tests
5. Refactor code
6. Repeat

Question 4

What are Testing Driven Developments shortcomings?

Answer 4

• Ideal for small component testing. Not ideal for full functional testing (UI testing/Database Testing).
• Management Support is required. Management sometimes feels writing tests is wasting development time. Studies show that debugging time is reduced when TDD is used.
• The tester and developer are the same person.
  - Tests may suffer the same issues as code. If the developer has a blind spot in terms of requirements it may not show up as a test case.
• Tests need to be maintained.
  - Detail must be provided early to ensure all test cases can be developed early. This model may not be as well suited to developing code with frequent design changes

Question 5

How would you make a test that failed if the test took longer than 5 seconds to run?

Answer 5

@Test (timeout=5000)

put that at the beginning

Question 6

How would you make a test handle an exception it is supposed to throw?

Answer 6

@Test(expected=IllegalArgumentException.class)

put that at the beginning

Question 7

What would the syntax look like when you needed to test for a time period and an exception?

Answer 7

@Test (expected=IllegalArgumentException.class,timeout=5000)

at the beginning

Question 8

When would you need to create your own little algorithm in a test instead of hard coding?

Answer 8

Only in the example where there was randomly generated and was testing for unique elements only.

all of the other types could have been hard coded