[v4] Trouble understanding what is being reported by this failing test

[e-e]

I have a JSON response from my API, and I'm using the response.assertJSONSubset(). The JSON data represents a user, and that user has a Postgres timestamp data type.

It looks roughly like this:

await user.reload(); // get the latest version of the test user

// this is simply testing that the correct response signature is returned, so is using 
const expectedUserData = {
  // ... other properties
  last_seen: user.last_seen,
}

response.assertJSONSubset({
  user: expectedUserData,
});

This results in the following failure:

1. GET /api/v1/user/:id
  expected { Object (user) } to contain subset { Object (user) }
  {
    user: {
      last_seen: "2021-12-16T02:29:28.264Z" => "2021-12-16T02:29:28.264Z"
    }
  }

What is this trying to tell me and how can I get this test to pass? I've also tried:

const expectedUserData = {
  // ... other properties
  last_seen: String,
}

and

const expectedUserData = {
  // ... other properties
  last_seen: Date,
}

which all result in the same output.

Thank you for any help in advance

[e-e]

Coming back to this almost exactly two years later, I finally think I figured it out. I think what was happening was that the response was coming back with the DateTime field as a string, but the model was holding a Date value. However, when the test runner when to display the difference, the toString method was being called, making them look identical when in fact they were the same value but different types