simple-canonical-object-methods.adoc

Simplified Testing of Canonical Object Methods

In Short

If you want to test the canonical object methods without much fuzz just implement the corresponding interface:

class ShouldHandleObjectContractsTest implements ShouldHandleObjectContracts<ComplexBean> {

    @Override
    public ComplexBean getUnderTest() {
        return new ComplexBean();
    }

The tests will be done by the default implementations of the Interface. See below for further explanation. If you want to test more thoroughly, take a look at Value-Object-Testing

Canonical?

The canonical object methods are the identity-related methods Object#equals() Object#hashCode(), the descriptive method Object#toString(). See 'Effective Java' for further information on why and how to implement them. In addition we test the object-serialization, see java.io.Serializable in that context as well.

General Structure

The implicit testing of said methods is done within the default implementations of certain interfaces:

de.cuioss.test.valueobjects.objects.TestObjectProvider<T>

In order to have something to test the corresponding interfaces all extend the TestObjectProvider, that provides the the method #getUnderTest() that provides an object that can be tested

de.cuioss.test.valueobjects.junit5.contracts.ShouldBeNotNull<T>

Defines a simple assertion verifying the given Object is not null. Base for later testing.

de.cuioss.test.valueobjects.junit5.contracts.ShouldImplementEqualsAndHashCode<T>

Verifies that the given Object implements Object#equals() and Object#hashCode() and checks some basic behavior like handling of null and symmetry.

class ShouldHandleEqualsAndHashCodeTest implements ShouldImplementEqualsAndHashCode<ComplexBean> {

    @Override
    public ComplexBean getUnderTest() {
        return new ComplexBean();
    }

de.cuioss.test.valueobjects.junit5.contracts.ShouldImplementToString<T>

Verifies that the given Object implements Object#toString().

class ShouldHandleToStringTest implements ShouldImplementToString<ComplexBean> {

    @Override
    public ComplexBean getUnderTest() {
        return new ComplexBean();
    }

de.cuioss.test.valueobjects.junit5.contracts.ShouldBeSerializable<T>

Verifies that the given Object implements java.io.Serializable and checks the actual serialization / deserialization of the given object.

class ShouldHandleSerializableTest implements ShouldBeSerializable<ComplexBean> {

    @Override
    public ComplexBean getUnderTest() {
        return new ComplexBean();
    }

de.cuioss.test.valueobjects.junit5.contracts.ShouldHandleObjectContracts<T>

Bundles all previously described interfaces as one-stop implementation, see first example.