The method shouldReceive does only exist in Mockery\MockInterface, but not in Aws\Firehose\FirehoseClient.
It seems like the method you are trying to call exists only in some of the
possible types.
Let’s take a look at an example:
classA{publicfunctionfoo(){}}classBextendsA{publicfunctionbar(){}}/** * @param A|B $x */functionsomeFunction($x){$x->foo();// This call is fine as the method exists in A and B.$x->bar();// This method only exists in B and might cause an error.}
This check marks private properties in classes that are never used. Those properties can be removed.