Or Constraint

OrConstraint combines two constraints and succeeds if either one succeeds.

Usage

<constraint>.Or.<constraint>

Examples

[Test]
public void OrConstraint_Examples()
{
    int value = 42;

    // Either condition can be true
    Assert.That(value, Is.LessThan(10).Or.GreaterThan(40));
    Assert.That(value, Is.EqualTo(0).Or.Positive);

    // String constraints
    Assert.That("test", Does.StartWith("te").Or.EndWith("ing"));

    // Multiple alternatives
    Assert.That(value, Is.EqualTo(1).Or.EqualTo(42).Or.EqualTo(100));
}

Evaluation Order and Precedence

Constraints are evaluated left to right and short-circuit when one succeeds:

[Test]
public void OrConstraint_NullPattern_Examples()
{
    int? nullable = null;

    // Null-or-value pattern (check null first!)
    Assert.That(nullable, Is.Null.Or.GreaterThan(0));  // Passes for null

    // Collection: empty or contains specific item
    var items = new List<int>();
    Assert.That(items, Is.Empty.Or.Contains(1));
}
Note

Or has higher precedence than And. The expression A.And.B.Or.C is evaluated as A.And.(B.Or.C).

See Also