DatapointSource

DatapointSourceAttribute is used to mark a field, property, or method as providing a collection of data values for Theory tests. The source must return either an array of the required type or an IEnumerable<T>.

This attribute is ignored for ordinary tests, including parameterized tests using [TestCase].

Usage

This is a parameterless attribute that can be applied to fields, properties, or methods.

[DatapointSource]

Applies To

Field	Property	Parameterless Methods	Test Methods	Test Fixtures (Classes)	Assembly
✅	✅	✅	❌	❌	❌

Note

Parameterless methods used with this attribute must return an array or IEnumerable<T>, and the element type must exactly match the Theory parameter type.

Example

[TestFixture]
public class PrimeNumberTests
{
    // DatapointSource on a field returning an array
    [DatapointSource]
    public int[] SmallPrimes = { 2, 3, 5, 7, 11, 13 };

    // DatapointSource on a property returning IEnumerable<T>
    [DatapointSource]
    public IEnumerable<int> MorePrimes
    {
        get
        {
            yield return 17;
            yield return 19;
            yield return 23;
        }
    }

    // DatapointSource on a method
    [DatapointSource]
    public int[] GetPrimesUnder100()
    {
        return new[] { 29, 31, 37, 41, 43, 47 };
    }

    [Theory]
    public void PrimeIsOddOrTwo(int prime)
    {
        // NUnit combines all datapoint sources for int type
        Assert.That(prime == 2 || prime % 2 != 0);
    }
}

Automatically Supplied Datapoints

NUnit automatically supplies datapoints for certain types:

Type	Automatic Values
`bool`	`true`, `false`
Any `enum`	All defined enum values

If you supply any datapoints for a parameter type, automatic datapoint generation for that type is suppressed.

Notes

The data source must be a member of the class containing the Theory.
The element type must exactly match the parameter type - no implicit conversions are performed.
Multiple DatapointSource attributes of the same type are combined.
Use Datapoint when you only need to provide a single value from a field.
The obsolete DatapointsAttribute was replaced by DatapointSourceAttribute in earlier versions.