Protocol => Mocks Data => Builders

Roadmap Define Maintainable Unit Test Create a Shared Vocabulary Examples When to Use Mocks

Define Maintainable Unit Test

Create a Shared Vocabulary

Examples

When to Use Mocks

Define Maintainable Unit Test

10% of Unit Tests Break If you really have a lot of unit tests, the amount of investment you'll have to make in maintaining those unit tests, keeping them up-to-date and keeping them passing, starts to become disproportional to the amount of benefit that you get out of them. — Joel Spolsky

If you really have a lot of unit tests, the amount of investment you'll have to make in maintaining those unit tests, keeping them up-to-date and keeping them passing, starts to become disproportional to the amount of benefit that you get out of them.

— Joel Spolsky

Maintainable Unit Tests The benefits of unit tests outweigh the costs as a codebase evolves.

The benefits of unit tests outweigh the costs as a codebase evolves.

Shared Vocabulary

Mocks Builders

xUnit Test Patterns

Mocks Builders

Mock Object A mock object is a simulated object that mimics the behaviour of a real object in controlled ways.

A mock object is a simulated object that mimics the behaviour of a real object in controlled ways.

Test Data Builder Builder Pattern build() method Default values Chainable configuration methods

Builder Pattern

build() method

Default values

Chainable configuration methods

Shared Vocabulary 4–Phase Test System Under Test Depended–On Component Mock Objects Test Data Builders

4–Phase Test

System Under Test

Depended–On Component

Mock Objects

Test Data Builders

Examples

Domain Model

public void should_recognize_pediatric_patient() { // setup Patient sut = aPatient ().age(17).build(); // exercise and verify assertTrue (sut.isPediatric()); assertTrue (!sut.isAdult()); }

public void should_recognize_pediatric_patient() { // setup Patient sut = aPatient ().age(17).build(); // exercise and verify assertTrue (sut.isPediatric()); assertTrue (!sut.isAdult()); }

public void should_recognize_pediatric_patient() { // setup Patient sut = aPatient ().age(17).build(); // exercise and verify assertTrue (sut.isPediatric()); assertTrue (!sut.isAdult()); } aPatient ().dob(april(1, 1992)).build();

Add Patient to Care Team Patient must be registered at the same Facility as the Care Team. Patient must meet the Care Team Membership Criteria (appropriate Age Category and Diagnosis).

Patient must be registered at the same Facility as the Care Team.

Patient must meet the Care Team Membership Criteria (appropriate Age Category and Diagnosis).

public class CareTeamMembershipService implements ICareTeamMembershipService { private CareTeamMembershipDao careTeamMembershipDao ; public void addMember(Patient patient, CareTeam careTeam) { if (!patient.isRegisteredAt(careTeam.getFacility())) { throw new CareTeamAdminException(); } if (!patient.meets(careTeam.getMembershipCriteria())) { throw new CareTeamAdminException(); } careTeamMembershipDao .create( patient.getId(), careTeam.getId()); } }

private final CareTeamMembershipDao careTeamMembershipDao = context .mock(CareTeamMembershipDao. class ); private final ICareTeamMembershipService sut = createCareTeamMembershipService(); public void should_permit_add_for_appropriate_care_team() { // setup final Facility jacobi = aFacility ().build(); final Patient patient = aPatient ().at(jacobi).age(18) .with(Diagnosis. DIABETES ).build(); final CareTeam careTeam = anAdultCareTeam ().at(jacobi) .with(Diagnosis. DIABETES ).build(); // verify context .checking( new Expectations() {{ one( careTeamMembershipDao ).create( patient.getId(), careTeam.getId()); }}); // exercise sut .addMember(patient, careTeam); }

private final CareTeamMembershipDao careTeamMembershipDao = context .mock(CareTeamMembershipDao. class ); private final ICareTeamMembershipService sut = createCareTeamMembershipService(); // verify @Test (expected=CareTeamAdminException. class ) public void should_disallow_add_adult_to_pediatric_care_team() { // setup final Facility jacobi = aFacility ().build(); final Patient patient = aPatient ().at(jacobi).age(18) . with (Diagnosis. DIABETES ).build(); final CareTeam careTeam = aPediatricCareTeam ().at(jacobi) .with(Diagnosis. DIABETES ).build(); // exercise sut .addMember(patient, careTeam); }

Examples Test vs Production API Builders as shared test asset Mocks and Builders as Firewalls

Test vs Production API

Builders as shared test asset

Mocks and Builders as Firewalls

When to Use Mocks

Mocks Builders

Protocol Data

Protocol => Mocks Data => Builders

Now What? Read xUnit Test Patterns Read Nat Pryce’s Builder posts Distinguish Protocol vs Data Try using Mocks with Builders

Read xUnit Test Patterns

Read Nat Pryce’s Builder posts

Distinguish Protocol vs Data

Try using Mocks with Builders

Contact Jason Cheong-Kee-You [email_address] Alistair McKinnell [email_address]

Jason Cheong-Kee-You

[email_address]

Alistair McKinnell

[email_address]

Resources xUnit Test Patterns http://xunitpatterns.com/ jMock http://www.jmock.org/ Test Data Builders http://nat.truemesh.com/archives/000714.html

xUnit Test Patterns

http://xunitpatterns.com/

jMock

http://www.jmock.org/

Test Data Builders

http://nat.truemesh.com/archives/000714.html

Credits Obstacle Race http://www.flickr.com/photos/foxypar4/1004464889/ Einstein Blackboard Writing Generator http://generator.kitt.net/2006/12/ einstein-blackboard-writing-generator.html Holy Grail http://www.flickr.com/photos/ spiritual_marketplace/2207966935/