Multiple correct results with Hamcrest (is there an or-matcher?)

Question

I am relatively new to matchers. I am toying around with hamcrest in combination with JUnit and I kinda like it.

Is there a way, to state that one of multiple choices is correct?

Something like

assertThat( result, is( either( 1, or( 2, or( 3 ) ) ) ) ) //does not work in hamcrest

The method I am testing returns one element of a collection. The list may contain multiple candidates. My current implementation returns the first hit, but that is not a requirement. I would like my testcase to succeed, if any of the possible candidates is returned. How would you express this in Java?

(I am open to hamcrest-alternatives)

marcospereira · Accepted Answer · 2022-01-11T15:21:54.320

137

assertThat(result, anyOf(equalTo(1), equalTo(2), equalTo(3)))

From Hamcrest tutorial:

anyOf - matches if any matchers match, short circuits (like Java ||)

See also Javadoc.

Moreover, you could write your own Matcher, which is quite easy to do.

edited Jan 11 '22 at 15:21

answered Sep 30 '08 at 14:13

marcospereira

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Looks like oneOf is the most recent. – Richard Jan 05 '22 at 00:06
Thanks, @Richard. Indeed, `oneOf` sounds like a good option for this case too: http://hamcrest.org/JavaHamcrest/javadoc/2.2/org/hamcrest/collection/IsIn.html#oneOf-T...- – marcospereira Jan 11 '22 at 15:22

score 87 · Answer 2 · edited Mar 30 '16 at 12:26

87

marcos is right, but you have a couple other options as well. First of all, there is an either/or:

assertThat(result, either(is(1)).or(is(2)));

but if you have more than two items it would probably get unwieldy. Plus, the typechecker gets weird on stuff like that sometimes. For your case, you could do:

assertThat(result, isOneOf(1, 2, 3))

or if you already have your options in an array/Collection:

assertThat(result, isIn(theCollection))

See also Javadoc.

edited Mar 30 '16 at 12:26

schnatterer

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answered Jul 02 '11 at 02:20

Tyler

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Hmmm... for some inexplicable reason my Eclipse environment (which is only about 6 months old) has an ancient Hamcrest library and I don't get these goodies. – CurtainDog Jun 27 '12 at 06:50
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Well, `assertThat((Set)null, is(either(empty()).or(nullValue())));` gives me a rather strange assertion error: `Expected: is (an empty collection or null) but: was null` for hamcrest `1.3`... – Jezor Apr 05 '18 at 13:05
isOneOf() seems to be deprecated now. – Jolta Feb 21 '20 at 15:06

score 0 · Answer 3 · answered Dec 12 '22 at 08:40

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In addition to the anyOf, you could also go for the either option, but it has a slightly different syntax:

assertThat(result, either(is(1)).or(is(2)).or(is(3))))

answered Dec 12 '22 at 08:40

Jacob van Lingen

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Multiple correct results with Hamcrest (is there an or-matcher?)

3 Answers3