And Constraint

AndConstraint combines two constraints and succeeds only if both succeed.

Usage

<constraint>.And.<constraint>

Examples

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

    // Both conditions must be true
    Assert.That(value, Is.GreaterThan(0).And.LessThan(100));
    Assert.That(value, Is.Positive.And.LessThanOrEqualTo(50).Or.GreaterThanOrEqualTo(40));

    // String constraints
    Assert.That("Hello World", Does.StartWith("Hello").And.EndWith("World"));
    Assert.That("test@example.com", Does.Contain("@").And.EndWith(".com"));

    // Null checking pattern (check null first!)
    int? nullable = 42;
    Assert.That(nullable, Is.Not.Null.And.GreaterThan(0));

    // Collection constraints
    Assert.That(new[] { 1, 2, 3 }, Is.Not.Empty.And.All.Positive);
}

Evaluation Order and Precedence

Constraints are evaluated left to right. This is important for null checks:

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

    // CORRECT: Check null first - fails gracefully with message for null
    Assert.That(value, Is.Not.Null.And.GreaterThan(9));
}
Note

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

See Also