Contains all test

This test checks whether one collection contains all elements of another. It is the opposite of the contains none test.

This operation corresponds to the mathematical concepts of superset and subset. Specifically, it checks whether the collection 𝐴 is a superset of 𝐵 (𝐴 ⊇ 𝐵) or, conversely, whether 𝐵 is a subset of 𝐴 (𝐵 ⊆ 𝐴).

Note that the result is always true if the second collection is empty, because the empty set is a subset of every set.

Is every unicorn in the room shining?

This might sound funny, but since there are no unicorns in the room, there's no unicorn that isn't shining. So, technically, they all are!

Also, keep in mind that neither the order nor duplicate elements affect the result since collections are treated as sets.

Syntax

This test has the following syntax:

/*<collection>*/ contains all of /*<collection>*/

Alternatively, you can use the following syntax:

/*<collection>*/ includes all of /*<collection>*/

Both forms have the same semantics. You can use whichever makes your query more expressive and easier to read.

You can negate the test to verify the contrary:

/*<collection>*/ does not contain all of /*<collection>*/

The same applies to the alternative syntax:

/*<collection>*/ does not include all of /*<collection>*/

However, consider using the contains none test instead of negating, as it is more expressive and easier to understand.

Parameters

These are the supported parameters:

collection

collection

The collection to check.

subset

collection

The collection whose elements must be contained in the other collection.

Examples

Here is an example of a collection that contains all the elements of another collection:

["a", "b", "c"] contains all of ["a", "b"] // true

And here is a counterexample:

["a", "b"] contains all of ["a", "b", "c"] // false

To negate the test, you can write:

["a", "b", "c"] does not contain all of ["a", "b"] // false

If the second collection is empty, the result is always true:

["a", "b", "c"] contains all of [] // true