Assertcontains on Strings in jUnit

Is there a nicer way to write in jUnit

String x = "foo bar";
Assert.assertTrue(x.contains("foo"));
4

10 Answers

If you add in Hamcrest and JUnit4, you could do:

String x = "foo bar";
Assert.assertThat(x, CoreMatchers.containsString("foo"));

With some static imports, it looks a lot better:

assertThat(x, containsString("foo"));

The static imports needed would be:

import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.CoreMatchers.containsString;
9

use fest assert 2.0 whenever possible EDIT: assertj may have more assertions (a fork)

assertThat(x).contains("foo");
2

Use hamcrest Matcher containsString()

// Hamcrest assertion
assertThat(person.getName(), containsString("myName"));

// Error Message
java.lang.AssertionError:
Expected: a string containing "myName"
     got: "some other name"

You can optional add an even more detail error message.

// Hamcrest assertion with custom error message
assertThat("my error message", person.getName(), containsString("myName"));

// Error Message
java.lang.AssertionError: my error message
Expected: a string containing "myName"
     got: "some other name"

Posted my answer to a duplicate question here

Use the new assertThat syntax together with Hamcrest.

It is available starting with JUnit 4.4.

It's too late, but just to update I got it done with below syntax

import org.hamcrest.core.StringContains;
import org.junit.Assert;

Assert.assertThat("this contains test", StringContains.containsString("test"));

You can use assertj-fluent assertions. It has lot of capabilities to write assertions in more human readable - user friendly manner.

In your case, it would be

 String x = "foo bar";
 assertThat(x).contains("foo");

It is not only for the strings, it can be used to assert lists, collections etc.. in a friendlier way

Example (junit version- 4.13)

import static org.assertj.core.api.Assertions.assertThat;
import org.junit.Test;

public class TestStr {

@Test
public void testThatStringIsContained(){
    String testStr = "hi,i am a test string";
    assertThat(testStr).contains("test");
 }

}
2

Another variant is

Assert.assertThat(actual, new Matches(expectedRegex));

Moreover in org.mockito.internal.matchers there are some other interesting matchers, like StartWith, Contains etc.

assertj variant

import org.assertj.core.api.Assertions;
Assertions.assertThat(actualStr).contains(subStr);

I've tried out many answers on this page, none really worked:

  • org.hamcrest.CoreMatchers.containsString does not compile, cannot resolve method.
  • JUnitMatchers.containsString is depricated (and refers to CoreMatchers.containsString).
  • org.hamcrest.Matchers.containsString: NoSuchMethodError

So instead of writing readable code, I decided to use the simple and workable approach mentioned in the question instead.

Hopefully another solution will come up.

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Maya Lin-Takahashi

Maya Lin-Takahashi

Consumer Tech & Gadget Reviewer

Maya is a hardware enthusiast who tests and reviews smart home devices, smartphones, wearables, and audio gear. She focuses on practical consumer value and build quality.

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