Testing multiple properties with single assertion

Every time I was trying to test an object's properties I was neither satisfied writing very verbose tests nor in using some of the out of the box hamcrest matchers. Although using the matchers was a big help, I never managed to make them read the way I wanted.

Another thing that was very important to me, I wanted to have a single assertion per method and a very descriptive description if the test did not pass.

I've decided to write my own matcher and hopefully it will be useful to other people. So, that's what I've done:

BeanMatcher

Hamcrest matcher to match multiple attributes of an object within a single assertion.

How to use it

	// Static imports
	import static org.craftedsw.beanpropertymatcher.matcher.BeanMatcher.has;
	import static org.craftedsw.beanpropertymatcher.matcher.BeanPropertyMatcher.property;
	import static org.hamcrest.MatcherAssert.assertThat;
	import static org.hamcrest.Matchers.equalTo;
	import static org.hamcrest.Matchers.greaterThan;
	// Imagine that you have a method that returns an object Person
	Person person = new Person();
	person.setFirstName("Sandro");
	person.setAge(25);
	person.setLastName("Mancuso");
	// Then you can test it like that
	assertThat(person, has(
	property("firstName", equalTo("Another dude")), // Mistmatch
	property("age", greaterThan(18)), // Use any matcher
	property("lastName", equalTo("Mancuso"))));

view raw BeanMatcher_example1.java hosted with ❤ by GitHub

NOTE: Make sure you are using org.hamcrest.MatcherAssert.assertThat instead of the JUnit one.

If you run this test, you will get a message like

	java.lang.AssertionError:
	Expected: property "firstName" = "Another dude"
	but: property "firstName" was "Sandro"

view raw BeanMatcher_error1.java hosted with ❤ by GitHub

Now, change the age check to

   property("age", greaterThan(60)) 

And you should get:

Testing object graphs

You can also do this

	Person person = new Person();
	person.setFirstName("Sandro");
	person.setAge(35);
	Country uk = new Country();
	uk.setName("United Kingdom");
	Address address = new Address();
	address.setPostcode("1234556");
	address.setCity("London");
	address.setCountry(uk);
	person.setAddress(address);
	assertThat(person, has(
	property("firstName", equalTo("Sandro")),
	property("age", greaterThan(18)),
	property("address.city", equalTo("London")),
	property("address.postcode", equalTo("1234556")),
	property("address.country.name", equalTo("United Kingdom"))));

view raw BeanMatcher_example2.java hosted with ❤ by GitHub

I use a combination of two matchers to do that:
- BeanMatcher: Provides the "has" method responsible to group all the property matchers.
- BeanPropertyMatcher: Provides the "property" method.

I expect to make more changes to them, so for the most up-to-date version, please check BeanMatcher on my github account.

Enjoy!!!