RIA 06 & 07 - Unit Testing in Detail

STAATLICHANERKANNTEFACHHOCHSCHULE

Author: Dip.-Inf. (FH) Johannes HoppeDate: 17.11.2010

01.12.2010

STUDIERENUND DURCHSTARTEN.

STAATLICHANERKANNTEFACHHOCHSCHULE

RIA – Rich Internet Applications

Author: Dip.-Inf. (FH) Johannes HoppeDate: 17.11.2010

01.12.2010

Unit Tests in General

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Unit Tests in General

Dependencies

› Every meaningful piece of software has dependenciesto other pieces of software

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SoftwareA

SoftwareB

SoftwareC

Unit Tests in General

Dependencies

› But usually software is tightly coupled to other software› Tightly coupled software is untestable!

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SoftwareA

SoftwareB

SoftwareC

Unit Tests in General

Dependencies

› We will concentrate on two types of dependencies:

1. A dependency by parameters:ClassA { Method(ClassB b) {…}}

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SoftwareA

SoftwareB

SoftwareC

Unit Tests in General

Dependencies

2. A dependency by the internal use of the “new” keyword:Class A { Method() { var c = new ClassC();}}

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SoftwareA

SoftwareB

SoftwareC

Unit Tests in General

Dependencies – Solution

› Our golden tools:

Interfaces & Dependency Injection

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SoftwareA

ISoftwareB

ISoftwareC

SoftwareB

SoftwareC

Unit Tests in General

Interfaces

› Interfaces are blueprints that describe a real implementation› Method are going to be independent

from the concrete implementation of the parameter:

ClassA { Method(ISoftwareB b) {…}}

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SoftwareA

ISoftwareB

ISoftwareC

SoftwareB

SoftwareC

Unit Tests in General

Dependency Injection

› We completely avoid the usage of the “new” keyword› Instead, we are “injecting” the required instance

from outside by using Interfaces› “Poor Man’s”-DI through constructor (works for UT, but is an anti-pattern!)› by a framework (here: Unity Application Block):

ClassA { [Dependency] public InterfaceC C { private get; set; }}

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Unit Tests in General

Loosely Coupled

1. If all dependencies are hidden by Interfaces2. We must not always use real-live objects3. We could also “cheat” with any object we want

(as long as it is implementing the interface)

Unit Testing!!

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Unit Tests in General

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Definitions

› SUT == System Under Test› Needs to be “fooled” so that it things it is talking with real collaborators

› Dummy › Objects passed around but never actually used› Used to fill required parameters in Unit Tests

› Fake› Objects with working implementations, but not suitable for production

(e.g. in memory database with hardcoded data)› Often used in software prototypes› Should not be used in unit tests, too

Unit Tests in General

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Definitions

› Stubs › Simple hand-written test-objects› Set up the environment for the Unit Test by returning hardcoded values

can be used for:

state verification

Determine whether the exercised method worked correctly byexamining the state of the SUT and its collaboratorsafter the method was exercised.

Unit Tests in General

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Definitions

› Mocks› More complex test-objects› pre-programmed with expectations which form a specification of the calls they

are expected to receive*

can be used for:

behavior verification

Determine whether the exercised method worked correctly bychecking if the SUT made thecorrect calls on the collaborators.

(* according to the definition of Martin Fowler)

Unit Tests in General

Definitions

› Many people (including me) are mixing the terms stub, fake and mock

› Mocking frameworks› Can create Mocks with a lot of magic inside› Can be used to build simple stubs, too!

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Unit Tests in General

Glossary

› MsTest – The unit testing framework that comes with Visual Studio

› Nunit – A quite popular unit testing framework which is open sourcewww.nunit.org

› Moq – A mocking framework that easy to use because of the lambda expression syntax

www.moq.me

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Unit Tests in General

Questions

?

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Review of our first Unit Test

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Unit Tests

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Ho

w?

Review of our first Unit Test

Explanation of Code

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Review of our first Unit Test

Dependencies

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WebNoteRepository

IWebNote

IObjectSet<Note>

Review of our first Unit Test

Dependencies

IWebNote – Entity Framework:

IWebNote – by our own Mock:

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WebNoteRepository

IWebNote

Review of our first Unit Test

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WebNoteRepository

IWebNote

IObjectSet<Note>

Dependencies

IObjectSet<Note> – Entity Framework:

IObjectSet<Note> – by our own Mock:

Chaining

› Real live: by poor man’s DI

› Unit Test: automatically by the class WebNoteBaseRepositoryTest› From which we are inheriting in our UT

Review of our first Unit Test

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Chaining

Unit Tests in General

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Mocked Repository

Base class from which we are inheriting

Required to prepare the mock

Unit Tests

Your tasks from last week:

› Try to write your first set of unit tests› Work together with you neighbor (2 persons, one team)› Use the Mock-Framework “Moq” from www.moq.me› Implement:

AddNoteTest, EditNoteTest, DeleteNoteTest DeleteNoteShouldThrowExceptionTest GetNoteShouldNotCallSaveChangesTest 6 Tests for the Controller

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Unit Tests

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Unit Tests

Tests: only with stubs

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Unit Tests

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Unit Tests

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Unit Tests

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Unit Tests

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Unit Tests

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Unit Tests

Tests: with Mocks

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Unit Tests

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Unit Tests

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Unit Tests

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Unit Tests

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behavior verification!

THANK YOUFOR YOUR ATTENTION

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