Java assertthat null

We can do this by adding the following snippet to our build. After we have added this dependency to the classpath, we can write assertions with AssertJ. Let's find out how we can do it. When we want to write assertions with AssertJ, we have to use the static assertThat method of the org. Assertions class. When we invoke this method, we have to know these two things:.

After we have invoked the assertThat method, we can write our assertions by using the returned assertion object. Also, because AssertJ provides a fluent API, each assertion method returns a reference to the used assertion object.

This means that we can chain assertions by simply invoking another assertion method. Next, we will take a look at some examples which demonstrate how we can write assertions with AssertJ.

If we want to verify that a boolean value is true , we have to write our assertion by invoking the isTrue method of the AbstractBooleanAssert class. In other words, we have to use an assertion that looks as follows:. If we want to verify that a boolean value is false , we have to write our assertion by invoking the isFalse method of the AbstractBooleanAssert class.

If we want to verify that an object is null , we have to write our assertion by invoking the isNull method of the AbstractAssert class. If we want to verify that an object isn't null , we have to write our assertion by invoking the isNotNull method of the AbstractAssert class.

If we want to verify that the expected value or object is equal to the actual value or object , we have to write our assertion by invoking either the isEqualTo method of the AbstractAssert class or the isEqualByComparingTo method of the AbstractComparableAssert class. The difference of these methods is explained in the following:.

For example, if we want to ensure that two integers are equal, we have to use an assertion that looks as follows:. If we want to verify that the expected value or object isn't equal to the actual value or object , we have to write our assertion by invoking either the isNotEqualTo method of the AbstractAssert class or the isNotEqualByComparingTo method of the AbstractComparableAssert class.

For example, if we want to ensure that two integers are not equal, we have to use an assertion that looks as follows:. If we want to ensure that two objects refer to the same object, we have to write our assertion by invoking the isSameAs method of the AbstractAssert class.

If we want to verify that two arrays are equal, we have to write our assertion by invoking the isEqualTo method of the AbstractArrayAssert class. If we want to verify that two arrays aren't equal, we have to write our assertion by invoking the isNotEqualTo method of the AbstractArrayAssert class. If we want to write an assertion which verifies that the size of an Iterable is correct, we can use one of these three options:. I tried it today and I absolutely love it.

We are going to create 4 different category of tests. Below tutorial covers almost all matchers testcases which will pass all the time. Just modify to create false positive and so on.

You need to add below maven dependency in your project. Just add this to pom. Just run above program as a Java Application and you should see result like below. Let us know if you face any issue running above program. Great post Tim! A very comprehensive article on assertThat. This is very useful to me and I refer to it time and time again.

I absolutely love the table in the Cross Reference section. Thanks for putting this together. I have added hamcrest-all1. Your email address will not be published. Save my name, email, and website in this browser for the next time I comment. Sep 18, Object Partners.

Readability The first benefit is that assertThat is more readable than the other assert methods. AssertionError at AssertionError: Expected: a string containing "abc" got: "def" As you can see, both values are returned in the error message. Flexibility As mentioned in the introduction, matchers can be chained, such as is not for example.

Only if none of them pass would the following error message be given: assertThat "test", anyOf is "test2" , containsString "ca" ; java. Portability An additional benefit to hamcrest library is its portability. Custom Matchers In the same way that custom assert methods can be written, custom matcher can also be written.

Description; import org. AssertionError: Expected: "test2" got: "test" Cross Reference There is a fair amount of information on the internet about this new matching mechanism, but what appears to be missing is a good cross reference of the old vs the new.

AssertionError: Expected: not null got: null Also both matchers can be typed as such: assertThat actual, nullValue String. See also in the same package: StringStartsWith, StringEndsWith There are many more that could be posted here, but instead here is a hierarchy of classes to look at.

About the Author Object Partners. June 2, at am. CoL says:. January 26, at pm. Mark says:. October 12, at pm. Le Stephane says:. November 28, at am. Mohammed Hossain says:. Rohit Jain Rohit Jain k 43 43 gold badges silver badges bronze badges. You need to import IsNull It's a static method in that class.

Just do static import , or use IsNull. Add import static org. In newer versions of Hamcrest the namespace has changed and you need import static org. Chetya Chetya 1, 1 1 gold badge 17 17 silver badges 26 26 bronze badges. The test-coding standard that I use favors assertThat over all other assertion methods for this reason.

The main advantage when using assertThat vs assertNul is that it is closer to an Englsih spoken phrase, just try to read any of your assertions to check it up. If you want to hamcrest , you can do import static org. Sajan Chandran Sajan Chandran Use the following from Hamcrest : assertThat attr.