OneTimeTearDown

OneTimeTearDownAttribute marks a method that runs once after every child test finished under a suite—for that fixture or setup-fixture scope. Pair it with OneTimeSetUp.

Put it on a method inside a TestFixture or a SetUpFixture.

Normally you declare multiple OneTimeTearDown methods spread across an inheritance chain (derived first at runtime, then base—see Inheritance below). Putting several methods on the same class is allowed, but execution order among them is undefined unless you constrain them logically.

Static and instance methods

OneTimeTearDown may be static or an instance method.

With LifeCycle.SingleInstance, an instance method runs once on the same shared fixture instance that held OneTimeSetUp/SetUp; use it for instance-field cleanup tied to shared setup.

With FixtureLifeCycle(LifeCycle.InstancePerTestCase), OneTimeTearDown must be static. It runs once after all tests despite each case having its own instance; instance teardown belongs in TearDown per test instead.

Methods may be async (Task / Task<T>); NUnit will wait for completion.

Test fixture versus SetUp fixture

  • TestFixture — teardown runs after all tests declared in that fixture (every parameterized case rooted there) finish, failed or passed unless something aborts scheduling earlier.
  • SetUpFixture — teardown runs once after everything under that SetUpFixture slice finishes, matching the broader “run once init / run once cleanup” workflow.

Teardown semantics for abstract or concrete bases mirror setup: inheritance causes code to participate per derived fixture type unless you refactor to SetUpFixture or static cleanup patterns when you truly need cross-suite lifetime control.

When teardown runs relative to failures

  • After OneTimeSetUp fails — once children are skipped, NUnit typically still invokes this fixture’s teardown chain so disposal paths can execute. See OneTimeSetUp — Failures and exceptions.

  • OneTimeTearDown failures — assertion failures or exceptions during teardown are recorded on the fixture / suite result as teardown failures. Individual child test outcomes are usually left as they were, but runners still surface the teardown problem.

  • Cancellation / abort — if execution ends in an abort state, teardown may not run (for example parallel stop). Normal stop-on-error still lets scheduled teardown phases run unless the dispatcher aborts the run.

NUnit schedules fixture teardown after every direct child of that suite finishes (runs, failures, or skips scheduled from parent setup). Do not treat teardown as a synchronous callback you can trigger from inside an individual [Test] method body.

Usage

This is a parameterless attribute that can only be applied to methods.

[OneTimeTearDown]

Applies To

Lifecycle Methods Test Methods Test Fixtures (Classes) Assembly
✅ ❌ ❌ ❌

Example

[Test]
public void Add()
{
    _hasRun = true;
    Assert.That(2 + 2, Is.EqualTo(4));
}

[OneTimeTearDown]
public void Cleanup()
{
    Assert.That(_hasRun, Is.True);
}

Inheritance

The OneTimeTearDown attribute is inherited from any base class. Therefore, if a base class has defined a OneTimeTearDown method, that method will be called after any test methods in the derived class.

You may define a OneTimeTearDown method in the base class and another in the derived class. NUnit will call base class OneTimeTearDown methods after those in the derived classes.

Warning

If a base class OneTimeTearDown method is overridden in the derived class, NUnit will not call the base class OneTimeTearDown method; NUnit does not anticipate usage that includes hiding the base method. Note that you may have a different name for each method; as long as both have the [OneTimeTearDown] attribute present, each will be called in the correct order.

Notes

  1. TestContext — like OneTimeSetUp, OneTimeTearDown runs in fixture / setup-fixture context, not per-test context. Exercise caution using TestContext APIs meant for [Test] methods.
  2. Multiple OneTimeTearDown methods on the same declaration run without a guaranteed mutual order unless you arrange them logically.
  3. Across inheritance, derived OneTimeTearDown methods run before base-class teardowns when both apply (see Inheritance).

See Also