README.md

Why Should I Use POJO-TESTER? {#why-use-it}

There are several reasons you should use it.

POJO-TESTER makes you more productive {#productivity}

Before POJO-TESTER, you had to write number of tests to check that you implemented your pojo-methods well. Let's see.

For simple Pojo class:

public class Pojo {
    private int a;
    private int b;
    // getters and setters
    // equals and hashCode
    // toString
}

You have to write several (8 in a good test case) tests:

@Test
public void Should_Equal_Itself() {
    // given
    final Pojo pojo = new Pojo();

    // when
    final boolean result = pojo.equals(pojo);

    // then
    assertTrue(result);
}

@Test
public void Should_Equal_Other_Object_With_Same_Values() {
    // given
    final Pojo pojo1 = new Pojo();
    final Pojo pojo2 = new Pojo();

    // when
    final boolean result = pojo1.equals(pojo2);

    // then
    assertTrue(result);
}

@Test
public void Should_Not_Equal_Null() {
    // given
    final Pojo pojo = new Pojo();

    // when
    final boolean result = pojo.equals(null);

    // then
    assertFalse(result);
}

@Test
public void Should_Not_Equal_Other_Object_With_Different_Values() {
    // given
    final Pojo pojo1 = new Pojo();
    final Pojo pojo2 = new Pojo();
    pojo2.setA(1);

    // when
    final boolean result = pojo1.equals(pojo2);

    // then
    assertFalse(result);
}

@Test
public void Should_Not_Equal_Object_Of_Different_Type() {
    // given
    final Pojo pojo = new Pojo();

    // when
    final boolean result = pojo.equals(new String());

    // then
    assertFalse(result);
}

@Test
public void Should_Generate_Same_Hash_Code_Every_Time() {
    // given
    final Pojo pojo = new Pojo();

    // when
    final int result1 = pojo.hashCode();
    final int result2 = pojo.hashCode();

    // then
    assertEquals(result1, result2);
}

@Test
public void Should_Generate_Same_Hash_Code_For_Equal_Objects() {
    // given
    final Pojo pojo1 = new Pojo();
    final Pojo pojo2 = new Pojo();

    // when
    final int result1 = pojo1.hashCode();
    final int result2 = pojo2.hashCode();

    // then
    assertEquals(result1, result2);
}

@Test
public void Should_Generate_Different_Hash_Code_For_Different_Objects() {
    // given
    final Pojo pojo1 = new Pojo();
    final Pojo pojo2 = new Pojo();
    pojo2.setA(1);

    // when
    final int result1 = pojo1.hashCode();
    final int result2 = pojo2.hashCode();

    // then
    assertNotEquals(result1, result2);
}

Do you really want to write all those tests each time you create a new pojo class?

Not really, just use POJO-TESTER

Improve your coverage {#improve-coverage}

In example above, you made it! You wrote 8 tedious tests! Or just copied them from another test class and changed the class name. You changed it, didn't you?

But still, this gives you coverage at low level.

POJO-TESTER gives you 100% coverage!

Will you improve your coverage with hand-written tests?

Not really, just use POJO-TESTER

Be resistant to bugs {#resistant-bugs}

Yeah, be resistant to bugs in your pojo-methods!

Let's say you not a big fan of coverage. You don't even want to write tests :)

Imagine a situation: you added a field in your pojo class:

public class Pojo {
    private int a;
    private int b;
    private int c;
    // getters and setters
    // equals and hashCode
    // toString
}

But you just forgot to include that field in your equals and hashCode methods.

What will happen?

All tests will pass, because you didn't write your tests for all the fields (of course, it would take one additional test per each field). You are pretty sure that you code is perfect! Yet you have 90% coverage. And who could guess that production code fails because of a hashCode method?

Do you want to be responsible for it?

Not really, just use POJO-TESTER.

Be resistant to changes {#resistant-changes}

Yeah, we don't forget to write an additional test for each extra field. But what happens if you have to remove fields, getters or setters?

Would you maintain all the broken tests?

Not really, just use POJO-TESTER

Don't write boilerplate tests {#avoid-boiler-plate-code}

Ok, lets assume you write pojo-methods tests by yourself. You even maintain your implementation-depending tests (really wrong tests).

How about getters, setters and toString tests? Will you write them all again? Really?

Do you still want to be copy-pasting all pojo-methods tests?

No matter how many fields you have, no matter if you write pojo-methods for your own or generate them. With POJO-TESTER you will have 100% coverage!

Just use POJO-TESTER:

@Test
public void Should_Pass_All_Pojo_Tests() {
    // given
    final Class<?> classUnderTest = Pojo.class;

    // when

    // then
    assertPojoMethodsFor(classUnderTest).areWellImplemented();
}