It looks like we don't need arrayEq and orderedArrayEq, because all the calls happen directly in an assert():

assert(arrayEq(a, b));
assert(orderedArrayEq(x, y));

When should we use these assertion methods instead:

assert.sameMembers(a, b);
assert.eq(x, y);

The assertion methods have better error messages by default: it can print the two values.

We should consider what else in jstests/aggregation/extras/utils.js can be removed, or moved to src/mongo/shell/assert.js.