info.michael-simons.eu

November has been a crazy month. Even though I joined Ralf in his Movember team and grew a mustache, I visited the JUG Münster at LVM Münster and gave my talk about SQL once again in a slightly updated version:

It felt very good being part of innoQ on this occasion.

Also very nice was the mentioning of my latest short tutorial in this week in spring.

Communications

What didn’t feel too good was the passing of my dear god father and especially his sad funeral. It really brought me down. As a result, I was in a bad mood for the last week and somewhat impatient and angry. Further down the road, communication got hard.

I already have been thinking a lot lately about communication problems and why they are so hard to solve in our business. As soon as things stress up (in a bad way), communication goes haywire. Often people build walls around themselves, myself included, and suddenly a bunch of good people who could form a good team, don’t. My friend and colleague Alex has written a great article (in German) on micro services, but honestly, it’s way more about various forms of communication as well. Check it out here.

While I tend to say I wanna do something with programming but without humans, the opposite is true. I love to listen, a good discussion, exchanging thoughts. Looking back at the past day, I spent several hours discussing options with the technical lead of our customer to evolve a platform and to onboard a new colleague into the project and the hours were well spent.

Spring Boot Buch

As hoped in last months recap, I got the preface from Jürgen himself and the book is somewhat jürgenized now.

The book itself is 95% done. It’s copy edited, spellchecked and ready to be set, but we are awaiting at least one release candidate of Spring Boot 2, which will see the light this month (December). I already did some changes on the Actuator parts and will do some big changes due to Spring Security 5. I have all the examples at GitHub. If you find something that doesn’t work, please let me know.

Java quickies and new, small projects

2 weeks ago I got nerd-sniped by Lukas, after complaining on twitter that I don’t have the amazing Spring Boot configuration mechanism for a task at hand. He proposed to just build it myself with plain JDK. I didn’t succeed fully, but did some nice, low-level stuff to map properties to classes. While working on that, I wrote this and some more in the pipeline. As I am a bit astonished how “new” Java 8 concepts still are for some, I will publish them the next months.

I have some new smaller projects:

• Die 13 Gezeichneten My first real Kotlin app. Such fun to write. The app is for my friends Judith and Christian
• simple-meetup A project written for an OBJEKTSpektrum article. I’m gonna use this for topics like testing, living documentation and later on DDD
• AssertJ demos My new love

The last project, AssertJ demos, come from experiments with AssertJ, both in the simple-meetup project as well as at the customers.

AssertJ got me while solving the following problem. Imagine this weird service, written in Java 9 but what was the other drinking while designing this return types?

public class WeirdService {
    public Object getSomething() {
        throw new UnsupportedOperationException("This is unsupported");
    }
 
    public Object getAString() {
        return "Hello";
    }
 
    public Object getTheRightThing() {
        return List.of(
            Map.of("firstName", "Michael", "lastName", "Simons"),
            Map.of("firstName", "Christina", "lastName", "Simons"),
            Map.of("firstName", "Anton", "lastName", "Simons"),
            Map.of("firstName", "Oskar", "lastName", "Simons")
        );
    }
}

AssertJ solves testing this freakish thing in every aspect:

class WeirdServiceTest {
 
    final WeirdService weirdService = new WeirdService();
 
    @Test
    @DisplayName("What to do? JUnit 5 or AssertJ?")
    public void demonstrateExceptionHandling() {
        // JUnit 5
        UnsupportedOperationException e = assertThrows(UnsupportedOperationException.class, () -> weirdService.getSomething());
        assertEquals("This is unsupported", e.getMessage());
 
        // AssertJ
        assertThatThrownBy(() -> weirdService.getSomething())
            .isInstanceOf(UnsupportedOperationException.class)
            .withFailMessage("This is unsupported");
    }
 
    @Test
    @DisplayName("Sometimes you have service that is just… weird… 🤡 Here it returns objects")
    public void niceTypeChecks() {
        assertThat(weirdService.getAString())
            .isInstanceOf(String.class)
            .asString()
            .isEqualTo("Hello");
 
        assertThat(weirdService.getTheRightThing())
            .isInstanceOf(List.class)
            .asList()
            .extracting("firstName")
            .containsExactly("Michael", "Christina", "Anton", "Oskar");
    }
}

First, look at the beautiful exception testing. I even find it nicer than the JUnit 5 way of doing stuff. And then, checking the returned type of the service, which comes with an elegant casting and then: extracting stuff from results is smart: It either works on properties or in this case, on map keys.

I collapsed several multi-page tests with that stuff into small chains of method calls. If you’re into testing, go have a look at AssertJ. Together with JUnit 5s possibilities to write the tests itself, its a great way to gain trust into your code.