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

No other choice that I know. Just checked the assert javadoc to be sure. Just a tiny little change, though:

assertTrue(actual.matches(expectedRegex));

EDIT: I have been using the Hamcrest matchers since pholser's answer, check that out too!

Answer 2

If you use assertThat() with a Hamcrest matcher that tests for regex matches, then if the assertion fails you'll get a nice message that indicates expected pattern and actual text. The assertion will read more fluently also, e.g.

assertThat("FooBarBaz", matchesPattern("^Foo"));

with Hamcrest 2 you can find a matchesPattern method at MatchesPattern.matchesPattern.

Answer 3

A matcher similar to Ralph's implementation has been added to the official Java Hamcrest matchers library. Unfortunately, it's not yet available in a release package. The class is on GitHub though if you want a look.

Answer 4

Because I was also looking for this functionality, I have started a project on GitHub called regex-tester. It's a library that helps ease testing regular expressions in Java (only works with JUnit currently).

The library is very limited right now, but it does have a Hamcrest matcher that works like this

assertThat("test", doesMatchRegex("tes.+"));
assertThat("test", doesNotMatchRegex("tex.+"));

More about how to use regex-tester is here.

Answer 5

it's not JUnit but here is another way with fest-assert :

assertThat(myTestedValue).as("your value is so so bad").matches(expectedRegex);

Answer 6

There is corresponding matcher in Hamcrest: org.hamcrest.Matchers.matchesPattern(String regex).

As development of Hamcrest stalled you can't use latest available v1.3:

testCompile("org.hamcrest:hamcrest-library:1.3")

Instead you need to use new dev series (but still dated by Jan 2015):

testCompile("org.hamcrest:java-hamcrest:2.0.0.0")

or even better:

configurations {
    testCompile.exclude group: "org.hamcrest", module: "hamcrest-core"
    testCompile.exclude group: "org.hamcrest", module: "hamcrest-library"
}
dependencies {
    testCompile("org.hamcrest:hamcrest-junit:2.0.0.0")
}

In test:

Assert.assertThat("123456", Matchers.matchesPattern("^[0-9]+$"));