CollectionEquivalent Constraint

CollectionEquivalentConstraint tests that two IEnumerables are equivalent - that they contain the same items, in any order. Two collections are equivalent if they have the same number of elements and every element in one collection has a matching element in the other.

Usage

Is.EquivalentTo(IEnumerable expected)
Is.Not.EquivalentTo(IEnumerable expected)

Modifiers

.IgnoreCase
.IgnoreWhiteSpace                     // From version 4.2
.Using(IEqualityComparer comparer)
.Using(IComparer comparer)
.Using<T>(IEqualityComparer<T> comparer)
.Using<T>(IComparer<T> comparer)
.Using<T>(Comparison<T> comparer)
.Using<T>(Func<T, T, bool> comparer)
.UsingPropertiesComparer()            // From version 4.1

Examples

// Basic equivalence - order doesn't matter
int[] expected = { 1, 2, 3 };
Assert.That(new[] { 3, 1, 2 }, Is.EquivalentTo(expected));

// Not equivalent - different counts matter
Assert.That(new[] { 1, 2, 2 }, Is.Not.EquivalentTo(expected));

// String comparison with case insensitivity
string[] names = { "Alice", "Bob", "Charlie" };
Assert.That(new[] { "alice", "BOB", "CHARLIE" }, Is.EquivalentTo(names).IgnoreCase);

// With custom comparer for complex objects
Assert.That(actualPeople, Is.EquivalentTo(expectedPeople).UsingPropertiesComparer());

Notes

  1. To compare items in a specific order, use Is.EqualTo() instead.
  2. Duplicate items matter: {1, 2, 2} is not equivalent to {1, 2, 3} even though they have the same length.
  3. The constraint checks that each item in one collection has exactly one matching item in the other, accounting for duplicates correctly.

See Also