I’m new using hamcrest. While I’m discovering how to use it I have been a doubt about when to use is or equalTo.
Is there any difference between is and equalTo, although it is conceptually or ocasionally? It seems to behave the same.
Assert.assertThat(actual, equalTo("blue"));
Assert.assertThat(actual, is("red"));
Why do you would use one instead of the other?
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Answer
The Javadoc for Matchers is pretty clear. is in all its overloaded forms is there for expressiveness.
The “main” is is is(Matcher<T> matcher) which:
Decorates another Matcher, retaining its behaviour, but allowing tests to read slightly more like an English phrase.
For example:
assertThat(cheese, is(equalTo(smelly)))instead of:
assertThat(cheese, equalTo(smelly))
is(T value) is:
A shortcut to the frequently used
is(equalTo(x)).
Allowing assertThat(cheese, is(smelly))
… and is(java.lang.Class<T> type) is:
A shortcut to the frequently used
is(instanceOf(SomeClass.class)).
Allowing assertThat(cheese, is(DairyFood.class))
… but this is deprecated in favour of isA(DairyFood.class).
What this boils down to is that is(foo) and equalTo(foo) are exactly equivalent in their behaviour, as long as foo is neither a Matcher nor a Class. You should use whichever you feel communicates your intent most clearly.