# WebSockets

When defining WebSockets, you normally declare a parameter of type `WebSocket` and with it you can read data from the client and send data to it.

It is provided directly by Starlette, but you can import it from `fastapi`:

```python
from fastapi import WebSocket
```

/// tip

	if !reflect.DeepEqual(lc.Keys(), []string{"key1"}) {
		t.Fatalf("value differs from expected")
	}

	if lc.Resize(0) != 0 {
		t.Fatalf("evicted count differs from expected")
	}
	if lc.Resize(2) != 0 {
		t.Fatalf("evicted count differs from expected")
	}
	lc.Add("key2", "val2")
	if lc.Resize(1) != 1 {
		t.Fatalf("evicted count differs from expected")
	}
}

func TestLRUEdgeCases(t *testing.T) {

  }

  ImmutableSortedMultiset<E> getSubMultiset(int from, int to) {
    checkPositionIndexes(from, to, length);
    if (from == to) {
      return emptyMultiset(comparator());
    } else if (from == 0 && to == length) {
      return this;
    } else {
      RegularImmutableSortedSet<E> subElementSet = elementSet.getSubSet(from, to);
      return new RegularImmutableSortedMultiset<>(

 * Negotiation Protocol) authentication. It contains the username extracted from the
 * SPNEGO authentication process, typically from a Kerberos ticket.
 */
public class SpnegoCredential implements LoginCredential, FessCredential {

    /** The username extracted from SPNEGO authentication. */
    private final String username;

    /**

    }

    void addEdge(Vertex from, Vertex to) throws CycleDetectedException {
        from.children.add(to);
        to.parents.add(from);
        List<String> cycle = findCycle(to);
        if (cycle != null) {
            // remove edge which introduced cycle
            removeEdge(from, to);
            throw new CycleDetectedException(

from typing import Annotated, Any
from unittest.mock import Mock, patch

from fastapi import Depends, FastAPI
from fastapi.testclient import TestClient

from docs_src.dependencies.tutorial010_py39 import get_db


def test_get_db():
    app = FastAPI()

    @app.get("/")
    def read_root(c: Annotated[Any, Depends(get_db)]):
        return {"c": str(c)}

    client = TestClient(app)

    dbsession_mock = Mock()

## `Depends()`

Dependencies are handled mainly with the special function `Depends()` that takes a callable.

Here is the reference for it and its parameters.

You can import it directly from `fastapi`:

```python
from fastapi import Depends
```

::: fastapi.Depends

## `Security()`

For many scenarios, you can handle security (authorization, authentication, etc.) with dependencies, using `Depends()`.

from typing import Callable

from fastapi import Body, FastAPI, HTTPException, Request, Response
from fastapi.exceptions import RequestValidationError
from fastapi.routing import APIRoute


class ValidationErrorLoggingRoute(APIRoute):
    def get_route_handler(self) -> Callable:
        original_route_handler = super().get_route_handler()

        async def custom_route_handler(request: Request) -> Response:
            try:

    class UpgradePathValidationTests {

        @ParameterizedTest(name = "from {0} to {1}")
        @MethodSource("provideValidPathUpgradeVersions")
        @DisplayName("should validate upgrade path")
        void shouldValidateUpgradePath(String from, String to) {
            assertTrue(ModelVersionUtils.canUpgrade(from, to));
        }

        private static Stream<Arguments> provideValidPathUpgradeVersions() {

     * @param to the target authenticator
     * @param from the source authenticator
     */
    public static void cloneInternal(Kerb5Authenticator to, Kerb5Authenticator from) {
        NtlmPasswordAuthenticator.cloneInternal(to, from);
        to.setUser(from.getUser());
        to.setRealm(from.getRealm());
        to.setService(from.getService());
        to.setLifeTime(from.getLifeTime());