Why doesn't this code attempting to use Hamcrest's hasItems compile?

ripper234_11236 0
Viewed 79977

Why does this not compile, oh, what to do?

import static org.junit.Assert.assertThat;
import static org.junit.matchers.JUnitMatchers.hasItems;

ArrayList<Integer> actual = new ArrayList<Integer>();
ArrayList<Integer> expected = new ArrayList<Integer>();
actual.add(1);
expected.add(2);
assertThat(actual, hasItems(expected));

error copied from comment:

cannot find symbol method assertThat(java.util.ArrayList<java.lang.Integer>, org.hamcreset.Matcher<java.lang.Iterable<java.util.ArrayList<java.lang.Integer>>>)
matcher hamcrest junit unit-testing java
9 Answers

You are comparing ArrayList<Integer> with int. The correct comparison is:

...
assertThat(actual, hasItem(2));

-- Edit --

I'm sorry, I've read it wrong. Anyway, the signature of hasItems you want is:

public static <T> org.hamcrest.Matcher<java.lang.Iterable<T>> hasItems(T... elements)

i.e., it accepts a variable number of arguments. I'm not sure if an ArrayList<T> is compatible, just guessing here. Try sending each item from the expected list interspersed by comma.

assertThat(actual, hasItems(2,4,1,5,6));

-- Edit 2 --

Just pasting here my comment, there is an equivalent expression for what you want, without using Hamcrest:

assertTrue(actual.containsAll(expected));
user_891120

Try

assertThat(actual, hasItems(expected.toArray(new Integer[0])));

to satisfy the matcher signature. No Eclipse around, so this might not work.

user_1126710

That error message looks like one produced by the javac compiler. I've found in the past that code written using hamcrest just won't compile under javac. The same code will compile fine under, say, the Eclipse compiler.

I think Hamcrest's generics are exercising corner cases in generics that javac can't deal with.

user_212340

For these cases when code does compile in Eclipse but javac shows errors please do help hamcrest by providing explicitly type parameter e.g. Matchers.hasItem()

user_6013210
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