Assert regex matches in JUnit

Question

Ruby\'s Test::Unit has a nice assert_matches method that can be used in unit tests to assert that a regex matches a string.

Is there anythi

Answer 1

You can use Hamcrest, but you have to write your own matcher:

public class RegexMatcher extends TypeSafeMatcher<String> {

    private final String regex;

    public RegexMatcher(final String regex) {
        this.regex = regex;
    }

    @Override
    public void describeTo(final Description description) {
        description.appendText("matches regex=`" + regex + "`");
    }

    @Override
    public boolean matchesSafely(final String string) {
        return string.matches(regex);
    }


    public static RegexMatcher matchesRegex(final String regex) {
        return new RegexMatcher(regex);
    }
}

usage

import org.junit.Assert;


Assert.assertThat("test", RegexMatcher.matchesRegex(".*est");

Answer 2

another alternative using assertj. this approach is nice as it allows you to pass the pattern object directly.

import static org.assertj.core.api.Assertions.assertThat;
assertThat("my\nmultiline\nstring").matches(Pattern.compile("(?s)my.*string", Pattern.MULTILINE));

Answer 3

You can use Hamcrest and jcabi-matchers:

import static com.jcabi.matchers.RegexMatchers.matchesPattern;
import static org.junit.Assert.assertThat;
assertThat("test", matchesPattern("[a-z]+"));

More details here: Regular Expression Hamcrest Matchers.

You will need these two dependencies in classpath:

<dependency>
  <groupId>org.hamcrest</groupId>
  <artifactId>hamcrest-core</artifactId>
  <version>1.3</version>
  <scope>test</scope>
</dependency>
<dependency>
  <groupId>com.jcabi</groupId>
  <artifactId>jcabi-matchers</artifactId>
  <version>1.3</version>
  <scope>test</scope>
</dependency>