Question

I used to compare lists like this, but it returns false in a test:

Assert.IsTrue(expected.SequenceEquals(actual));

And tried converting to json and it worked:

Assert.AreEqual(expected.ToJson(), actual.ToJson());

Values seems to be equal, what could be different? How to find out what is different in the lists?

Updated:

My class:

public class Department
{
    [BsonId]
    public ObjectId Id { get; set; }    
    public string Name { get; set; }            

    public override string ToString()
    {
        return Id.ToString();
    }
}

Answer 1

If MyClass implements IEquatable<MyClass>, then try this:

expected.Sort(); 
actual.Sort();
if (Enumerable.SequenceEqual(actual, expected)) { ... }

If it does not implement IEquatable then you could expect strange behavior, since the object references will be compared in the two lists, and not their fields:

using System;
using System.Collections.Generic;
using System.Linq;

public class MyClassA
{
  private int i;
  public MyClassA(int i) { this.i = i; }
}

public class MyClassB : IEquatable<MyClassB>
{
  private int i;
  public MyClassB(int i) { this.i = i; }
  public bool Equals(MyClassB other) { return this.i == other.i; }
}

public class Program
{
  public static void Main()
  {
    var actual1 = new List<MyClassA>() { new MyClassA(1), new MyClassA(2), new MyClassA(3) };
    var expected1 = new List<MyClassA>() { new MyClassA(1), new MyClassA(2), new MyClassA(3) };
    Console.WriteLine(Enumerable.SequenceEqual(actual1, expected1));

    var a1 = new MyClassA(1);
    var a2 = new MyClassA(2);
    var a3 = new MyClassA(3);
    var actual2 = new List<MyClassA>() { a1, a2, a3 };
    var expected2 = new List<MyClassA>() { a1, a2, a3 };
    Console.WriteLine(Enumerable.SequenceEqual(actual2, expected2));

    var actual3 = new List<MyClassB>() { new MyClassB(1), new MyClassB(2), new MyClassB(3) };
    var expected3 = new List<MyClassB>() { new MyClassB(1), new MyClassB(2), new MyClassB(3) };
    Console.WriteLine(Enumerable.SequenceEqual(actual3, expected3));

    var actual4 = new List<MyClassB>() { new MyClassB(1), new MyClassB(2), new MyClassB(3) };
    var expected4 = new List<MyClassB>() { new MyClassB(3), new MyClassB(2), new MyClassB(1) };
    Console.WriteLine(Enumerable.SequenceEqual(actual4, expected4));
  }
}

Output:

False
True
True
False