CODEWITHSUNDEEP
c#.netunit-testingnunit
Jon
Jon

Reputation: 40062

Using CollectionAssert.Contains against a collection

I want to write something like:

var list = new List<int>(){1,2,3};
var bigList = new List<int>(){1,2,3,4,5,6,7,8,9};

CollectionAssert.Contains(bigList, list);

I can get an error similar to:

 Expected: collection containing < 1,2,3 >
 But was:  < 1,2,3,4,5,6,7,8,9 >

Is it possible to use the contains method against another collection?

Upvotes: 6

Views: 5673

Answers (4)

Jakob Ojvind Nielsen
Jakob Ojvind Nielsen

Reputation: 972

The purpose of using CollectionAssert.IsSubsetOf(list, bigList) is most often that you want to see which of the items from list is not included in the bigList. Testing that all items from list is contained in bigList only return true or false, which doesn't give me any helpful debugging information of what is wrong. I want the test to fail and also give the information which of the items was not in bigList.

So for me, I always convert the statement CollectionAssert.IsSubsetOf(list, bigList) to 

var list = new List<int>(){0,1,2,3,9}; // note the 0 and 9 is added to the list
var bigList = new List<int>(){1,2,3,4,5,6,7,8};

CollectionAssert.IsEmpty(list.Except(bigList));

Which gives the result

Expected <empty>
But was: <0, 9>

In other words, list contains 0 and 9, which are not contained in bigList

Upvotes: 0

onedaywhen
onedaywhen

Reputation: 57073

Same functionality, different syntax (NUnit's constraint style, closer to natural language, which is a quality of a good test):

var list = new List<int>(){1,2,3};
var bigList = new List<int>(){1,2,3,4,5,6,7,8,9};

Assert.That( list, Is.SubsetOf( bigList ) );

Upvotes: 1

Arnaud F.
Arnaud F.

Reputation: 8462

From MSDN

Use CollectionAssert.IsSubsetOf:

var list = new List<int>(){1,2,3};
var bigList = new List<int>(){1,2,3,4,5,6,7,8,9};

CollectionAssert.IsSubsetOf(list, bigList);

Upvotes: 2

Henk Holterman
Henk Holterman

Reputation: 273711

The signature is 

   CollectionAssert.Contains (ICollection collection, Object element)

And it checks if element (singular) is inside collection.
It is not a method to check for sub-lists.

You should probably use:

    CollectionAssert.IsSubsetOf (ICollection subset, ICollection superset)

Upvotes: 7

Related Questions