public void BeEqualBySimilarity(
string productId1,
decimal price1,
uint amount1,
string productId2,
decimal price2,
uint amount2,
bool expected)
{
var sut = new InvoiceItem(productId1, price1, amount1);
var other = new InvoiceItem(productId2, price2, amount2);
Assert.Equal(expected, sut.Equals(other));
Assert.Equal(expected, sut.Equals((object)other));
Assert.Equal(expected, sut == other);
Assert.Equal(expected, !(sut != other));
Assert.Equal(expected, sut.GetHashCode() == other.GetHashCode());
}