Incorrect behaviour of overrideDefaultInitialization when there is no default constructor

[fmbenhassine]

When there is no default constructor in the randomized type, default initialization in the constructor is overridden (ie fields are randomizerd) even when the overrideDefaultInitialization is not set.

Here is a failing test with v3.4.0:

@Data
public static class BeanWithDefaultFieldValuesAndNoDefaultConstructor {
    private Long id;
    private String defaultNonNullValue = "default";
    private String defaultNonNullValueSetByConstructor;

    public BeanWithDefaultFieldValuesAndNoDefaultConstructor(Long id) {
        this.id = id;
        defaultNonNullValueSetByConstructor = "defaultSetByConstructor";
    }
}

@Test
public void whenOverrideDefaultInitializationIsFalseAndThereIsNoDefaultConstructor_thenShouldKeepDefaultFieldValues() {
    // Given
    enhancedRandom = aNewEnhancedRandomBuilder().overrideDefaultInitialization(false).build();

    // When
    BeanWithDefaultFieldValuesAndNoDefaultConstructor bean = enhancedRandom.nextObject(BeanWithDefaultFieldValuesAndNoDefaultConstructor.class);

    // Then
    assertThat(bean.getId()).isNotNull();
    assertThat(bean.getDefaultNonNullValue()).isEqualTo("default");
    assertThat(bean.getDefaultNonNullValueSetByConstructor()).isEqualTo("defaultSetByConstructor");
}

What happens behind the scene is that:

• random beans does not find a default constructor, it delegates object creation to objenesis
• objenesis by-passes the constructor and creates a new instance of the bean (here, all fields are null)
• random beans finds that all fields are null, hence it randomizes fields (which is not what we want to do, since we didn't set the overrideDefaultInitialization parameter)

[fmbenhassine]

Not sure if this issue is valid. Non default constructor will never be called (by objenesis).

The only trick I see, when there is no default constructor, is to try to call (one of) the existing constructor(s) with random parameters.. But this is too much work IMO and not worth it. Random Beans was designed to randomize Java beans, which by definition, provide a default constructor.

[fmbenhassine]

@PascalSchumacher What do you think?

Should we keep the behaviour of overrideDefaultInitialization as is and update documentation to add a note on default constructor?

[PascalSchumacher]

I agree that adding support for calling non-default constructors would require serious work and I'm not sure how useful it is.

Let's keep and document the current behavior for now.

[fmbenhassine]

Great, I will update the documentation about that.