`toStrictEqual` should not compare return value of `get` function

let a = 0;
class Foo {
    get foo(): i32 {
        return ++a;
    }
}

expect(new Foo()).toStrictEqual(new Foo());

  [Actual]: Foo {
      foo: 3
  }
[Expected]: Foo {
      foo: 4
  }

It not only compares, but also produces side effects.

[jtenner]

Steps to prove this:

1. Install jest
2. create a test that uses expect(someRef).toStrictEqual(anotherRef)
3. validate the get property function on someRef is executed.

This behavior is by design.

If you think that you truly need strict equality, I might recommend wrapping your object with a special function like this:

function wrap(a: A): B {
  // copy each a value you want to test to a type B
  let b = new B();
  b.prop1 = a.prop1;
  return b;
}

expect(wrap(myA)).toStrictEqual(wrap(otherA));

[yjhmelody]

Well, I got it