MaxTime

MaxTimeAttribute is used on test methods to specify a maximum time in milliseconds for a test case. If the test takes longer than the specified time to complete, it is reported as a failure.

Unlike CancelAfter, this attribute does not cancel the test - it waits for the test to complete and then checks the elapsed time.

Constructor

MaxTimeAttribute(int milliseconds)
Parameter Type Description
milliseconds int The maximum elapsed time in milliseconds. If the test exceeds this time, it fails.

Named Parameters

Parameter Type Description
WarningTime int An optional warning threshold in milliseconds. If the test takes longer than this time but less than the maximum time, the test result is set to Warning. A value of 0 (the default) disables the warning threshold. (NUnit 5+)

Applies To

Test Methods Test Fixtures (Classes) Assembly
✅ ❌ ❌

Examples

Basic Usage

[TestFixture]
public class PerformanceTests
{
    [Test]
    [MaxTime(1000)]
    public void OperationCompletesWithinOneSecond()
    {
        // This test fails if it takes more than 1000ms
        var result = PerformQuickCalculation();
        Assert.That(result, Is.Not.Null);
    }

    [Test]
    [MaxTime(5000)]
    public async Task AsyncOperationCompletesWithinFiveSeconds()
    {
        // MaxTime also works with async tests
        await Task.Delay(100);
        Assert.Pass();
    }

    private object PerformQuickCalculation()
    {
        // Simulate a quick calculation
        return new object();
    }
}

Assertion Failures Take Precedence

[TestFixture]
public class MaxTimeVsAssertionTests
{
    [Test]
    [MaxTime(2000)]
    public void AssertionFailuresTakePrecedence()
    {
        // If both assertion fails AND time exceeds,
        // the assertion failure is reported
        var result = 2 + 2;
        Assert.That(result, Is.EqualTo(4));
    }
}

Warning Threshold

[TestFixture]
public class MaxTimeWarningThresholdTests
{
    [Test]
    [MaxTime(1000, WarningTime = 200)]
    public void OperationWithWarningThreshold()
    {
        // Test passes if it completes within 1000ms.
        // If it takes more than 200ms but less than 1000ms, the result is Warning.
        Thread.Sleep(201);
    }
}

Notes

  1. Any assertion failures take precedence over the elapsed time check. If a test both fails an assertion and exceeds the time limit, the assertion failure is reported.
  2. This attribute does not cancel or abort the test if the time is exceeded. It waits for the test to complete, then compares the elapsed time to the maximum.
  3. For tests that need to be cancelled when they exceed a time limit, use CancelAfter Attribute instead.
  4. The timing includes the test method execution only, not SetUp or TearDown methods.
  5. The Timeout Attribute uses Thread.Abort and only works on .NET Framework.
  6. The optional WarningTime named parameter (added in NUnit 5+) sets a soft threshold: if the test exceeds it but still passes within the maximum time, the result is Warning rather than Failure.

See Also