I recently did a few days of TDD training for a client. They asked me to help them test and refactor a class that created XML from an internal domain model. This gave me the opportunity to examine a bigger pattern. I wondered where the domain model came from. Looking through the code base, I found that the same or similar data structures were dealt with many places. As often is the case, I also found a bit of code that parsed an XML structure and output the domain model.

In order to smoke test web applications, I like to run-to-end smoke tests that start the web server and drives a web browser to interact with the application. Here is how this may look: public class BookingWebTest { private DataSource dataSource; private Server server; @Before public void createServer() throws Exception { dataSource = DataSources.getTestDataSource(); new EnvEntry("jdbc/applicationDs", dataSource); server = new Server(0); server.setHandler(new WebAppContext("src/main/webapp", "/test")); server.start(); } private final WebDriver browser = new HtmlUnitDriver(); @Test public void shouldShowCreatedBookings() throws Exception { PersonDao personDao = new PersonDao(dataSource); Person person = new Person(); person.

There are only so many ways to test that your persistence layer is implemented correctly or that you’re using an ORM correctly. Here’s my canonical tests for a repository (Java-version): import static org.fest.assertions.api.Assertions.*; public class PersonRepositoryTest { private PersonRepository repository; // TODO < == you must initialize this @Test public void shouldSaveAllProperties() { Person person = samplePerson(); repository.save(person); // TODO: Make sure your repository flushes! assertThat(repository.find(person.getId()) .isNotSameAs(person) .isEqualTo(person) .isEqualsToByComparingFields(person); } @Test public void shouldFindByCaseInsensitiveSubstringOfName() { Person matching = samplePerson(); Person nonMatching = samplePerson(); matching.

Two of my favorite libraries in C#: FluentAssertions and NUnit (of course). NUnit has a “hidden” gem (that is, it’s well documented, yet few developers use it): [TestCase]. Look at this: using FluentAssertions; using NUnit.Framework; public class RomanNumeralsTest { [TestCase(3333, "MMMCCCXXXIII")] [TestCase(555, "DLV")] [TestCase(999, "CMXCIX")] [TestCase(444, "CDXLIV")] public void ItConvertsNumbersToRomanNumerals(int number, string roman) { ToRoman(number).Should().Be(roman); } } The [TestCase] lets us easily have several test cases implemented by the same method.