Repeat

RepeatAttribute is used on a test method to specify that it should be executed multiple times. By default, the test repeats until a failure occurs or all repetitions complete successfully.

Constructors

RepeatAttribute(int count)
RepeatAttribute(int count, bool stopOnFailure)
Parameter Type Description
count int The number of times to run the test.
stopOnFailure bool Whether to stop repeating when a test fails. Default is true.

Properties

Property Type Description Default
StopOnFailure bool Whether to stop repeating when a test fails. When false, all repetitions run regardless of failures. true
RequiredPassPercentage int The minimum percentage of runs (1–100) that must pass for the test to succeed. When set below 100, StopOnFailure is treated as false (and must not be explicitly set to true); iterations run up to the repeat count unless StopWhenOverallResultDetermined is enabled. 100
StopWhenOverallResultDetermined bool When true and RequiredPassPercentage is below 100, stops iterating as soon as the final outcome is determined — either because the pass threshold is already guaranteed or can no longer be reached. false
Note

The StopOnFailure property was added in NUnit 4.3.0.

Note

The RequiredPassPercentage and StopWhenOverallResultDetermined properties were added in NUnit 5.0.

Applies To

Test Methods Test Fixtures (Classes) Assembly
✅ ❌ ❌

Examples

Default Behavior (Stop on Failure)

[Test]
[Repeat(5)]
public void TestMethod1()
{
    Assert.Pass();
}

Continue on Failure


private int count2;

[Test,Explicit]  // Marking the test as Explicit to avoid failing our doc build. You can skip this.
[Repeat(5, StopOnFailure = false)]
public void TestMethod3()
{
    count2++;
    Assert.That(count2, Is.Not.EqualTo(3)); // Intentional failure on 3rd iteration
}

Pass Threshold

When testing non-deterministic systems (such as LLM-based tests or flaky integrations), you can allow a percentage of runs to fail. The test passes as long as at least RequiredPassPercentage percent of the runs succeed.

// The test passes if at least 80% of the 10 runs succeed.
// Useful for non-deterministic systems where some variation is acceptable.
[Test]
[Repeat(10, RequiredPassPercentage = 80)]
public void NonDeterministicTest()
{
    bool result = CallFlakyService();
    Assert.That(result, Is.True);
}

private bool CallFlakyService() => true; // placeholder

Early Stop When Outcome Is Determined

When StopWhenOverallResultDetermined is true, NUnit stops iterating as soon as it knows whether the threshold will be met or missed, saving unnecessary test runs.

// Stops as soon as NUnit can guarantee pass or failure:
//  - Early success: enough passes accumulated (threshold already guaranteed).
//  - Early failure: too many failures (threshold no longer achievable).
[Test]
[Repeat(10, RequiredPassPercentage = 80, StopWhenOverallResultDetermined = true)]
public void NonDeterministicTestWithEarlyStop()
{
    bool result = CallFlakyService();
    Assert.That(result, Is.True);
}

Notes

  1. When StopOnFailure is true (default), the test stops at the first failure.
  2. When StopOnFailure is false, all repetitions run and all failures are collected.
  3. When RequiredPassPercentage is set below 100, StopOnFailure must not be explicitly set to true — combining the two is a configuration error that produces ResultState.Error without running the test. Setting StopOnFailure=false explicitly alongside a threshold is valid. When StopOnFailure is left at its default (not explicitly set), it is silently treated as false so repetitions continue after failures (unless StopWhenOverallResultDetermined is enabled).
  4. When RequiredPassPercentage is below 100 and StopWhenOverallResultDetermined is true, NUnit exits the loop as soon as the result is certain:
    • Early success: the number of passes already guarantees the threshold regardless of the remaining runs.
    • Early failure: even if all remaining runs pass, the threshold can no longer be reached.
  5. If RepeatAttribute is used on a parameterized method, each individual test case is repeated independently.
  6. It is not currently possible to use RepeatAttribute on a TestFixture or any higher level suite. Only test methods may be repeated.

See Also