Showdown of the Asserts

This talk is based on heated discussions about the syntax of asserts. Do you like the good old assertNotEquals(id, c.getId()) or do you prefer something fancier like assertThat(c.getId(), is(not(equalTo(id))))?
We will take a quick look at the differences between asserts in JUnit, TestNG, Hamcrest, AssertJ, Truth, and Spock. This topic is at least as important as Vim vs Emacs and tabs vs spaces!

Transcript

1. Voxxed Days Bristol Showdown of the Asserts Philipp Krenn̴̴@xeraa
2. Assert Dictionary state a fact or belief confidently and forcefully
3. This is not an assertive talk
4. JUnit + tempus-fugit
8. TestNG JUnit compatible testing framework
9. Hamcrest AssertJ (fest) Truth Replace JUnit / TestNG asserts
10. Spock Testing framework written in Groovy JUnit runner Mocking / Stubbing
11. Example Code assertNotEquals(unexpected, actual); assertThat(actual, is(not(equalTo(unexpected)))); Different order Longer Additional dependency
12. JUnit public class AdderTest { @Test public void testAdd(){ Adder adder = new Adder(); assertEquals(3, adder.add(1, 2)); } }
13. // JUnit assertEquals(3, adder.add(1, 2)); // TestNG assertEquals(adder.add(1, 2), 3); // Hamcrest assertThat(adder.add(1, 2), equalTo(3)); // AssertJ assertThat(adder.add(1, 2)).isEqualTo(3); // Truth assertThat(adder.add(1, 2)).isEqualTo(3); // Spock expect: adder.add(1, 2) == 3
14. JUnit final Double MY_PI = 3.14; assertEquals( "My own pi is close to the real pi", Math.PI, MY_PI, 0.1)
15. // JUnit assertEquals(Math.PI, MY_PI, 0.1) // Hamcrest assertThat(MY_PI, closeTo(Math.PI, 0.1)); // AssertJ assertThat(MY_PI).isCloseTo(Math.PI, Percentage.withPercentage(3)); // Truth assertThat(MY_PI).isWithin(0.1).of(Math.PI); // Spock with Hamcrest matcher expect: MY_PI closeTo(Math.PI, 0.1)
16. It's a mess Order of arguments Traditional vs fluent interfaces Different styles
17. Winner? Stick to one tool / combination
18. “Want to get much better at writing unit tests? For the next week, try writing every single assertion using equal()” https://medium.com/javascript-scene/what-every-unit-test- needs-f6cd34d9836d
19. PS: Junit5 https://junit-team.github.io/junit5/