# Testing { #testing }

Thanks to <a href="https://www.starlette.io/testclient/" class="external-link" target="_blank">Starlette</a>, testing **FastAPI** applications is easy and enjoyable.

It is based on <a href="https://www.python-httpx.org" class="external-link" target="_blank">HTTPX</a>, which in turn is designed based on Requests, so it's very familiar and intuitive.

# Testing Dependencies with Overrides { #testing-dependencies-with-overrides }

## Overriding dependencies during testing { #overriding-dependencies-during-testing }

There are some scenarios where you might want to override a dependency during testing.

You don't want the original dependency to run (nor any of the sub-dependencies it might have).

# Testing a Database { #testing-a-database }

You can study about databases, SQL, and SQLModel in the <a href="https://sqlmodel.tiangolo.com/" class="external-link" target="_blank">SQLModel docs</a>. 🤓

There's a mini <a href="https://sqlmodel.tiangolo.com/tutorial/fastapi/" class="external-link" target="_blank">tutorial on using SQLModel with FastAPI</a>. ✨

# Testing WebSockets { #testing-websockets }

You can use the same `TestClient` to test WebSockets.

For this, you use the `TestClient` in a `with` statement, connecting to the WebSocket:

{* ../../docs_src/app_testing/tutorial002.py hl[27:31] *}

/// note

For more details, check Starlette's documentation for <a href="https://www.starlette.io/testclient/#testing-websocket-sessions" class="external-link" target="_blank">testing WebSockets</a>.

# Testing Events: lifespan and startup - shutdown { #testing-events-lifespan-and-startup-shutdown }

When you need `lifespan` to run in your tests, you can use the `TestClient` with a `with` statement:

{* ../../docs_src/app_testing/tutorial004.py hl[9:15,18,27:28,30:32,41:43] *}


You can read more details about the ["Running lifespan in tests in the official Starlette documentation site."](https://www.starlette.io/lifespan/#running-lifespan-in-tests)

    boolean unused = create().containsKey(null);
  }

  public void testContainsValue() {
    boolean unused = create().containsValue(null);
  }

  public void testGet() {
    Object unused = create().get(null);
  }

  public void testPut() {
    create().put(null, null);
  }

  public void testPutAll() {
    create().putAll(new HashMap<String, Integer>());
  }

  public void testKeySet() {

var isRaceBuilder = strings.HasSuffix(testenv.Builder(), "-race")

func BenchmarkIndexByte(b *testing.B) {
	benchBytes(b, indexSizes, bmIndexByte(IndexByte))
}

func BenchmarkIndexBytePortable(b *testing.B) {
	benchBytes(b, indexSizes, bmIndexByte(IndexBytePortable))
}

func bmIndexByte(index func([]byte, byte) int) func(b *testing.B, n int) {
	return func(b *testing.B, n int) {
		buf := bmbuf[0:n]

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.annotations.J2ktIncompatible;
import com.google.common.testing.EqualsTester;
import com.google.common.testing.NullPointerTester;
import java.util.Objects;
import junit.framework.TestCase;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/**

    // A concrete implementation of the abstract NtlmServlet for testing purposes.
    private static class TestNtlmServlet extends NtlmServlet {
        private static final long serialVersionUID = 1L;

        @Override
        protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
            // Do nothing - just for testing
        }

        @Override

import static com.google.common.truth.Truth.assertThat;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.GwtIncompatible;
import com.google.common.testing.EqualsTester;
import java.util.Objects;
import org.jspecify.annotations.NullMarked;

/**
 * Tests {@link SingletonImmutableTable}.
 *
 * @author Gregory Kick
 */
@GwtCompatible
@NullMarked