Add isNotThrownBy() method as opposite to isThrownBy()

[quaff]

It can be used like:

    assertThatExceptionOfType(IllegalArgumentException.class).isNotThrownBy(() -> {
      // no exception
    });

    assertThatExceptionOfType(IllegalArgumentException.class).isNotThrownBy(() -> {
      throw new IllegalStateException();
    });

Check List:

• Unit tests : YES
• Javadoc with a code example (on API only) : YES

[quaff]

Do I need create a separate issue before submit PR? @scordio

[scordio]

No, that's ok @quaff, and thanks a lot for the proposal!

Your intention is clear. I would like to double-check the user experience in case of errors, i.e., when the code doesn't throw anything vs. when the code throws the exception that shouldn't be thrown.

Would you have time to try these two cases and post the results here? It would help us get on board faster 🙂

[quaff]

Your intention is clear. I would like to double-check the user experience in case of errors, i.e., when the code doesn't throw anything vs. when the code throws the exception that shouldn't be thrown.

Would you have time to try these two cases and post the results here? It would help us get on board faster 🙂

If I understand correctly, the test case should cover that, the assertion will success if the code doesn't throw anything or throws the exception that shouldn't be thrown.