Unit Testing

The “no time for testing” death spiral

Pressure

Testing

Errors

Direct

Inverse

Test-Driven Development by Example, Kent Beck

Legacy Code

Michael Feathers introduced a definition of legacy code as code without tests

Wikipedia

Unit Testing Isolation

Doubles

Mock
Stub
Fake
Dummy
Spy

Algunos consejos

Testing temprano
TDD
No sacrificar calidad por entrega
Probar nuevas formas*

Testing temprano

public class Dummy {

    public void dummyMethod() {
        return DummyRepository.getInstance().someMethod();
    }

}

public class Dummy {

    private repository = DummyRepository.getInstance();

    public void setRepository(DummyRepository value) {
        this.repository = value;
    }

    public void dummyMethod() {
        return this.repository.someMethod();
    }

}

TDD

No sacrificar calidad por entrega

Coverage

public class SomeClass {

    public void someMethod(int param) {
        if (param > 0 || param < 0) {
            return param * 2;
        }

        return 10;
    }

}

public class SomeClassTest {

    private SomeClass someClass = new SomeClass();

    @Test
    public void someMethodGreaterThanZero() throws Exception {
        int response = this.someClass.someMethod(10);
        assertEqual(20, response);
    }

    @Test
    public void someMethodLessThanZero() throws Exception {
        int response = this.someClass.someMethod(-10);
        assertEqual(-20, response);
    }
}

Line coverage

Branch coverage

¿JUnit?

Spock

Groovy
Retrocompatible con Java
BDD

JUnit vs Spock

def "should throw RestException when FECHA_NAC not exists"() {
    given:
    Variables variables = new Variables();
    variables.add(new VariableItem("FECHA_VUELTA", "10/4/2010"));
    variables.add(new VariableItem("FECHA_IDA", "10/4/2010"));
    repository.generateEstimation(_ as Variables) >> new Estimation()

    when:
    this.estimationsService.generateEstimation(variables);

    then:
    notThrown(RestException)
}

@Test(expected = RestException.class)
public void shouldThrowRestExceptionWhenFECHA_NAC_NotExists() throws Exception {
    Variables variables = new Variables();
    variables.add(new VariableItem("FECHA_VUELTA", "10/4/2010"));
    variables.add(new VariableItem("FECHA_IDA", "10/4/2010"));

    when(estimationsRepository.generateEstimation(variables)).thenReturn(new Estimation());

    this.estimationsService.generateEstimation(variables);
}

JUnit vs Spock

def "Encrypt"() {
    expect:
    CustomHash.encrypt(a) == b

    where:
    a     || b
    'abc' || 'YWJj'
    ''    || ''
    null  || ''
}

@Test(expected = RestException.class)
public void shouldThrowRestExceptionWhenFECHA_NAC_NotExists() throws Exception {
    Variables variables = new Variables();
    variables.add(new VariableItem("FECHA_VUELTA", "10/4/2010"));
    variables.add(new VariableItem("FECHA_IDA", "10/4/2010"));

    when(estimationsRepository.generateEstimation(variables)).thenReturn(new Estimation());

    this.estimationsService.generateEstimation(variables);
}