Lecture 6-Test smells

Question 1

What are the 11 test smells?

Answer 1

1.Eager test
2.Lazy test
3.Mystery Guest
4.Resource optimism
5.Test run war
6.General fixture
7.Assertion roulette
8.Indirect testing
9.For testers only
10.Sensitive equality
11. Test code duplication

Question 2

When do we use Eager Test?

Answer 2

When a test method checks several methods of the object to be tested.

Question 3

What is the solution of Eager Test?

Answer 3

Separate the test code into test methods that test only one method –> use meaningful name to specify purpose

*can slow down tests due to increased setup/teardown overhead.

Question 4

When do we use Lazy Tests?

Answer 4

When several test methods check the same method using the same fixture.

Question 5

What is the solution of Lazy Tests?

Answer 5

Use Inline Method to join them together.

Question 6

When do we use Mystery Guest?

Answer 6

When a test uses external resources and introduces hidden dependencies.

Question 7

What are the solutions of Mystery Guest(2 options)?

Answer 7

If we don’t need external resources:
-Refactoring: Inline Resource

If we need external resources:
-Setup external resource

Question 8

When do we use Resource Optimism?

Answer 8

When non-deterministic behaviour is caused in test outcomes.

Question 9

What is the solution of Resource Optimism?

Answer 9

Use Setup External Resource to allocate and/or initialize all resources that are used.

Question 10

When do we use Test Run War?

Answer 10

When the tests run fine as long as you are the only one testing but fail when more programmers run them.

Question 11

What is the solution of Test Run War?

Answer 11

Apply Make Resource Unique to overcome interference.

Question 12

When do we use General Fixture?

Answer 12

When the setUp fixture is too general and different tests only access part of it.

Question 13

What is the solution of General Fixture(2 methods)?

Answer 13

-Use Extract Method only for that part that is shared by all tests.
-Use Inline Method to put the rest in method that uses it.

Question 14

When do we use Assertion Roulette?

Answer 14

When theres a number of assertions in a test method that have no explanation –> if one of the assertions fails, you don’t know which one it is.

Question 15

What is the solution of Assertion Roulette?

Answer 15

Use Add Assertion Explanation to remove the smell –> optional first argument gives an explanatory message to the user when the assertion fails.

Question 16

Eager test vs Assertion roulette

Answer 16

Eager test –> testing multiple functionality

Assertion roulette–> one functionality but many assertions without explanation

Question 17

When do we use Indirect testing?

Answer 17

When a test class contains methods that actually perform tests on other objects.

Question 18

What is the solution of Indirect testing (2 methods)?

Answer 18

1.Apply Extract Method to move indirection to the appropriate test class.
2.Apply Move Method on that part of the test.

Question 19

When do we use For testers only?

Answer 19

When a production class contains methods that are only used by test methods:
(1) are not needed and can be removed
OR
(2) are only needed to set up a fixture for testing –>they usually have names or comments

Question 20

What is the solution of For testers only (1 method) ?

Answer 20

Apply Extract Subclass to move methods from class to a new subclass in test code and use that subclass to perform the tests on.

Question 21

When do we use Sensitive Equality?

Answer 21

Whenever the toString method for an object is changed and tests start failing.

Question 22

What is the solution of Sensitive Equality?

Answer 22

Apple Equality Method (assertEquals) to replace toString equality checks by real equality checks.

Question 23

When do we use Test code duplication?

Answer 23

When test code may contain undesirable duplication. The parts that set up test fixtures are susceptible to this.

Question 24

What is the solution of Test Code Duplication(1 method)?

Answer 24

Use Extract Method.