Timeout

Warning

This attribute is obsolete on .NET 5 and later. Starting from NUnit 4.5, usage of the Timeout attribute on .NET 5+ is reported as a test failure. Use CancelAfter or MaxTime instead.

TimeoutAttribute is used to specify a timeout value in milliseconds for a test case. If the test runs longer than the specified time, it is immediately cancelled and reported as a failure.

Constructor

TimeoutAttribute(int timeout)
Parameter Type Description
timeout int The timeout value in milliseconds.

Applies To

Test Methods Test Fixtures (Classes) Assembly
✅ ✅ ✅

.NET 5+ Alternatives

Since Thread.Abort() was removed in .NET 5, this attribute no longer works reliably. Use these alternatives:

Alternative Description
CancelAfter Cooperative cancellation via CancellationToken. Your test must handle the token.
MaxTime Reports tests that exceed expected time, but doesn't cancel them.
dotnet test --blame-hang-timeout Aborts the entire test run if any test exceeds the timeout.

Example (.NET Framework Only)

[Test, Timeout(2000)]
public void PotentiallyLongRunningTest()
{
    // Test will be cancelled if it runs longer than 2 seconds
}

[TestFixture, Timeout(5000)]
public class TimeSensitiveTests
{
    [Test]
    public void Test1()
    {
        // Inherits 5 second timeout from fixture
    }

    [Test, Timeout(1000)]
    public void QuickTest()
    {
        // Overrides fixture timeout with 1 second
    }
}

Notes

  1. Deprecated on .NET 5+: This attribute uses Thread.Abort(), which was removed in .NET 5. On .NET 5+, the test will be cancelled for reporting purposes, but the code continues running in the background.
  2. The timeout covers setup, teardown, and the test method itself. Before/after actions may also be included depending on where they were specified.
  3. When a timeout occurs during execution, no guarantees can be made about which phases completed.
  4. When debugging (debugger attached), the timeout is not enforced.
  5. A default timeout can also be set via the console runner's --timeout option or in a .runsettings file when using dotnet test.

See Also