Testing with JUnit

Question 1

What happens if an assertions fails

Answer 1

A single unit test may have one to many assertions - assertions aren’t required for a unit test to be valid

If an assertion fails, the method will stop running

Question 2

Should production code be run when running tests

Answer 2

No, the tests should call the required methods automatically and the actual program shouldn’t be run

Question 3

What should the name of the test be for the method createAccount

Answer 3

testCreateAccount
=> This method will call the createAccount method

You can have multiple test methods per method, so long as it begins with testCreateAccount

Question 4

How do you test your tests

Answer 4

Prove tests by introducing bugs and ensure that the tests catch the bugs

Question 5

What are the 5 properties of good tests

Answer 5

Automatic - tests should run automatically

Thorough - All possible cases of code

Repeatable - Should produce the same result for a given input (tolerance of what is acceptable as “the same” should be introduced)

Independent - No tests should rely on each other or the environment that it’s in

Professional - Written and maintained to the same standard as the shipped code

Question 6

We can use Right-BICEP to help construct tests. What does this stand for

Answer 6

Right => Boundary results are correct?

B => Boundary conditions

I => Inverse relationships (e.g. in maths you can use addition to check subtraction and use subtraction to check addition)

C => Can you cross-check results using other means

E => Error condition (e.g. if exceptions are caught)

P => Performance characteristics within bounds?

Question 7

What do we need to take into consideration before we test methods

Answer 7

Any dependencies;

When testing methods, they may have interactions with other methods of the object or its attributes. These instances should be set up before tests for this specific method is tested

Question 8

Give 3 reasons why unit tests are important

Answer 8

Reduces time spent on debugging

Communicates code’s intended use - illustrates how you want code to perform on various inputs and conditions

Code shouldn’t drift away from the limits put on them by the tests

Question 9

What do the following annotations represent

@Before
@BeforeClass
@After
@AfterClass
@Test

Answer 9

1) Executing statements before a specific test case
2) Execute statements before all test cases
3) Execute statements after each test case (e.g. resetting variables)
4) Execute statements after all test cases (e.g. releasing resources after execution of all test cases)

5) Declares that it’s a test method
This is the main test method and most tests should be written under this method

Question 10

What cant AssertEquals be used on

Why is it unwise to use AssertEquals on floating points

What is the purpose of the string parameter in the following code
assertEquals (String msg, expected, actual)

Answer 10

Objects and primitive types

There is only finite memory thus floating point values aren’t exact; we would need to specify some tolerance

This is the message that will be displayed if the test fails

Question 11

THEORY CARD

Assertions aren’t essential when writing unit tests

Assertions enables automatic unit testing

Answer 11

If an assertion fails, the method will stop running altogether