Find out the most user friendly pojo tester api for testing

[sta-szek]

What is the most user friendly / given-when-then convention compatible way to invoke pojo tests?

// given
PojoTester tester = new PojoTester();
PojoTester tester = new PojoTester(fieldValueChanger);
PojoTester tester = new PojoTester().using(fieldValueChanger);

Class coffee = Coffee.class;
Class cake = Cake.class;

Class[] classes = new Class[]{coffee, cake};

// when

// then
tester.test(coffee);
tester.testAll(coffee, cake,);
tester.testAll(classes);

OR

// given
Class coffee = Coffee.class;
Class cake = Cake.class;

Class[] classes = new Class[]{coffee, cake};

// when

// then
assertThat(class).using(fieldValueChanger).hasWellImplemented...();
assertThat(class1, class2).using(fieldValueChanger).haveWellImplemented...();

EXPLANATION

Currently test and testAll methods throw exception when pojo has invalid equals, hashcode or toString method implementation.

NESTED CLASSES

You can also define nested classes to change in your main class e.g.

A {
  B b;
  C c.
}
Class baseClass = A.class;
Class[] nestedClasses = new Class[]{B.class, C.class};

test(baseClass, nestedClasses )

KIND OF TESTS

There is no option to choose which tests should be run (equals, hashcode or toString).
How do you want to provide it? E.g.

new PojoTester(EQUALS | HASHCODE | TO_STRING)
or
new PojoTester().addTesters(new EqualsTester(), ...)
or
assertThat(class).using(new HashCodeTester()).hasWellImplemented...();

CHANGING FIELDS

At this moment you can provide you own fieldsValuesChanger that should change field of specific type e.g. Coffee.
In order to do this you have to extend AbstractFieldsValuesChanger class and implement some methods.

If you do not specify your own fields values changer and pojo tester could not change field value then it sets it either to null or class.instantiate()

[jerckov]

Maybe something like this will be cool:

@Test
public void shouldCheckPojo() {
   // given
   Class cofe = Cofe.class;

   // when
   final PojoResult result = testPojo(cofe);

   // then
   assertPojo(result).hasWellImplemented();
 }

Although it's splitted to two lines but BDD structured is preserved.

[m-dabrowa]

I like the second approach

assertThat(class).using(fieldValueChanger).hasWellImplemented...();

But @jerckov has right. You wrote about given-when-then and you had empty section when. He introduced PojoResult and this seems a little strange to me. Maybe BDD is not applicable for PojoTester.

If you want to chose than the second proposition is better.

[losoft]

I think the second option is more natural for me.
And something similar to:

// given
final EqualsTester equalsTester = new CustomEqualsTester();

// when
final Configuration configuration = new DefaultConfiguration().withCustom(equalsTester)
                                                              .skip(Configuration.ToStringTester)

// then
assertThat(class).using(configuration).hasWellImplemented...();

[sta-szek]

[SemionPar]

assertThat(class) convention is surely the most appealing one.

Have you considered annotation based approach? You could annotate the pojos you want to test with @PojoTester (options = ), then use custom test runner to run tests for all pojos in a single test class, using @Test methods to provide sets of configuration. If you are dealing with primarily dumb pojos this could spare you some time writing and maintaining all those test classes.

[sta-szek]

assertThat(...)... almost complete, just resolve some problems with IllegalAccessException.
Annotations sounds delicious - but this makes your production code test framework dependend.
This means you have to have fat-jar pojo-tester in production jar... 😞
But for people who do not care about that it could be a nice feature, so you can report feature issue 😄

BTW
Solution for this problem is to write gradle plugin, that will delete all pojo-tester annotations from your source code before compiling.