# assert/contains? Assert a collection or string contains an element or substring. Used inside `deftest` blocks. ## Syntax

[assert/contains? $container $element]

## Parameters - `$container` — collection or string to search. - `$element` — element or substring expected to be present. ## Examples

[assert/contains? $xs 3]
[assert/contains? "hello world" "world"]

## Returns `true` on success; raises a runtime error on failure. ## See Also `assert/empty?`, `assert/not-empty?`, `deftest`