Bring back skipped tests

[snewcomer]

ref #379

@sandstrom - yes but only with changeset.set('dogs', [...oldDogs, newDog])

[sandstrom]

@snewcomer Awesome news, will look into it this afternoon! 😄

[RobbieTheWagner]

@snewcomer @sandstrom is this saying you cannot do addObject or pushObject and must instead create a new array and set it on the changeset? We should document hasMany and belongsTo in the README probably?

[sandstrom]

@rwwagner90 That's how I understood it yes, but I'm not 100% sure

[snewcomer]

Some doc updates would probably be a good idea! This is mainly due to our use of tracked (without track-built-ins)

[RobbieTheWagner]

@snewcomer thanks for the clarification. Is this only for hasMany or is this any array? I can take a stab at writing some docs.

[snewcomer]

https://github.com/poteto/ember-changeset/blob/master/tests/integration/main-test.js#L187

Lmk if these tests are helpful at all and/or is different than what you though it should be! And docs are always definitely appreciated!