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Assertions against an Array

Introduction​

Let's start by getting an array of users from a JSON response and make some assertions against it.

Let's say the body looks like this:

{
  "data": {
    "users": [
      {
        "id": 123,
        "firstName": "Jason",
        "age": 41
      }
      // ... more users objects ...
    ]
  }
}

We can query for an array of user objets:

const users = context.find("data.users[*]");

Make sure it's an array:

users.must.be.an.array();

Must Have Length​

Let's say we queried for the first 50 users, so we'd expect the size of the array to match that.

users.must.have.length.equal(50);

If we were on the last page of results, that might fail. So let's assertion no more than 50.

users.must.have.length.be.lessThanOrEquals(50);

We can the inverse if we prefer with the not statement.

users.must.have.length.not.be.greaterThan(50);

Must All​

We expect that all items in teh array are objects.

users.must.all.be.an.object();
users.must.all.have.properties(["id", "firstName", "age"]);

See the power of all? Instead of looping through all of the elements and making individual assertions against each, we were able to make a single assertion against every array item!

We can query individual columns within that array to assert against those as well.

const ids = context.find("data.users[*].id");
ids.must.all.be.an.integer();
ids.must.all.be.greaterThan(0);

We can also do things with negative assertions, using all...not

ids.must.all.not.be.greaterThan(999999);

Must Have Some / Must Have Any​

Sometimes you may expect some of them to be something, but not necessarily all of them. We got you!

ids.must.have.some.be.an.evenInteger();

The some and any statements do the same thing. Use the one that is grammatically better.

ids.must.have.any.be.a.number();

Usually any sounds weird though, unless you're doing a not assertion, which brings us to...

Must Have None / Must Not Have Any​

names.must.have.none.be.null();

This would be the same thing as

names.must.not.have.any.be.null();

Must Have Only​

If we want to be specific about how many will meet a certain criteria, use only.

Let's switch it up now and select names.

const names = context.find("data.users[*].firstName");

Now let's say there can only be one Jason!

names.must.have.only(1).equal("Jason");

You can use any positive number as the argument.

names.must.have.only(50).be.alphanumeric();

Must Have At Least​

ids.must.have.atLeast(15).be.an.evenInteger();

Must Have At Most​

names.must.have.atMost(10).be.uppercase();