AllItems Constraint

AllItemsConstraint applies a constraint to each item in an IEnumerable, succeeding only if all items satisfy the constraint. An exception is thrown if the actual value does not implement IEnumerable.

Usage

Is.All.<constraint>
Has.All.<constraint>

Examples

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

    // All items must satisfy the constraint
    Assert.That(numbers, Is.All.GreaterThan(0));       // All positive
    Assert.That(numbers, Is.All.LessThan(10));         // All less than 10
    Assert.That(names, Is.All.Not.Null);               // No nulls
    Assert.That(names, Is.All.Not.Empty);              // No empty strings
    Assert.That(names, Is.All.InstanceOf<string>());   // All are strings

    // Has.All is equivalent to Is.All
    Assert.That(numbers, Has.All.GreaterThan(0));

    // Combining with property constraints
    Assert.That(names, Is.All.Length.GreaterThan(2));  // All names > 2 chars

    // Complex constraints
    Assert.That(numbers, Is.All.InRange(1, 10));
    Assert.That(names, Is.All.Matches<string>(n => n.Length <= 5));
}

Notes

  1. Is.All and Has.All are interchangeable.
  2. The constraint fails on the first item that doesn't match.
  3. An empty collection satisfies Is.All for any constraint (vacuous truth).

See Also