Testing

Question 1

What is software reliability?

Answer 1

Probability that a software system will not cause failure under specified conditions.

Measured by uptime, MTTF (mean time till failure), crash data.

Question 2

How many bugs are estimated to be in complex software systems?

Answer 2

10-50 bugs per 1000 lines of code.

Question 3

What is testing in software development?

Answer 3

A systematic attempt to reveal errors.

Question 4

What does a failed test indicate?

Answer 4

An error was demonstrated.

Question 5

What does a passed test indicate?

Answer 5

No error was found (for this particular situation).

Question 6

What are unit tests?

Answer 6

Tests that should be non-interactive and made up of a huge number of statements that exercise some code and compare the computed result with the expected result.

Question 7

What is the purpose of a test driver?

Answer 7

To report the number of successes and number of failures when finished.

Question 8

What is the benefit of a comprehensive unit test suite?

Answer 8

Allows you to refactor your code with confidence.

Question 9

What do unit tests typically contain?

Answer 9

Assertions about the behaviour of your software.

Question 10

What is a JUnit test class?

Answer 10

A class created to test another class, containing various ‘test case’ methods to run.

Question 11

What does the @Test annotation signify in JUnit?

Answer 11

Marks a method as a JUnit test case.

Question 12

What does assertTrue(test) do?

Answer 12

Fails if the boolean test is false.

Question 13

What does assertFalse(test) do?

Answer 13

Fails if the boolean test is true.

Question 14

What does assertEquals(expected, actual) do?

Answer 14

Fails if the values are not equal.

Question 15

What does assertNotNull(value) check?

Answer 15

Fails if the given value is null.

Question 16

What is regression testing?

Answer 16

Re-executing prior unit tests after a change to ensure old fixed bugs are still fixed.

Question 17

What is Test-Driven Development (TDD)?

Answer 17

A process that starts with designing and developing tests for every small functionality of an application before writing the code.

Question 18

What is the TDD cycle?

Answer 18

Write a test, make it run, change code to make it right (refactor), repeat process.

Question 19

What is the importance of naming test cases descriptively?

Answer 19

Clear, long, descriptive names help identify what the test is checking.

Question 20

What are breakpoints in debugging?

Answer 20

Lines of code where you want to ‘pause’ the execution of a program.

Question 21

What does the continue feature do in debugging?

Answer 21

Continues the execution of the program until the next breakpoint or until the program terminates.

Question 22

What is a call stack?

Answer 22

Allows you to see the current stack of method calls.

Question 23

What is the purpose of the watches window in debugging?

Answer 23

Allows you to ‘watch’ the value of a variable.

Question 24

Fill in the blank: A bug can be ______ or can hide in your code until much later.

Answer 24

visible

Question 25

True or False: Unit testing is looking for errors in a subsystem in isolation.

Answer 25

True

Question 26

What is the purpose of setup and teardown methods in JUnit?

Answer 26

To run code before and after each test case method is called.

Question 27

What happens if a method with @Test does not finish running within the specified timeout?

Answer 27

The method will be considered a failure.

Question 28

What should tests avoid to be trustworthy?

Answer 28

Logic, such as if/else statements, loops, and try/catch.

Question 29

What is the main goal of regression testing?

Answer 29

To ensure that a feature that used to work, no longer works due to code changes.

Question 30

What does JUnit provide to help write tests?

Answer 30

Assert commands to check expectations in test methods.