SomeItems Constraint

SomeItemsConstraint applies a constraint to each item in an IEnumerable, succeeding if at least one item satisfies the constraint. An exception is thrown if the actual value does not implement IEnumerable.

Usage

Has.Some.<constraint>
Has.Member(object expected)
Contains.Item(object expected)
Does.Contain(object expected)

Modifiers

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

Examples

[Test]
public void SomeItemsConstraint_Examples()
{
    int[] numbers = { 1, 2, 3, 4, 5 };
    string[] names = { "Alice", "Bob", "Carol" };

    // At least one item must satisfy the constraint
    Assert.That(numbers, Has.Some.GreaterThan(3));      // At least one > 3
    Assert.That(numbers, Has.Some.EqualTo(3));          // Contains 3
    Assert.That(names, Has.Some.Length.EqualTo(3));     // At least one 3-char name

    // Collection membership (all equivalent)
    Assert.That(numbers, Has.Member(3));
    Assert.That(numbers, Contains.Item(3));
    Assert.That(numbers, Does.Contain(3));
    Assert.That(numbers, Has.Some.EqualTo(3));

    // Custom comparison for membership
    Assert.That(names, Has.Some.EqualTo("alice").IgnoreCase);
    Assert.That(names, Has.Some.EqualTo("bob").Using(StringComparer.OrdinalIgnoreCase));
}

Contains examples

[Test]
public void CollectionContains_Examples()
{
    int[] intArray = [1, 2, 3];
    string[] stringArray = ["a", "b", "c"];

    Assert.That(intArray, Has.Member(3));
    Assert.That(stringArray, Has.Member("b"));
    Assert.That(stringArray, Contains.Item("c"));
    Assert.That(stringArray, Has.No.Member("x"));
    Assert.That(intArray, Does.Contain(3));
}

Notes

  1. Has.Member(), Contains.Item(), and Does.Contain() are all equivalent to Has.Some.EqualTo().
  2. The constraint succeeds as soon as the first matching item is found.
  3. An empty collection always fails this constraint.
  4. For testing substring containment in strings, see SubstringConstraint.

See Also