private HostSpecifier(String canonicalForm) {
    this.canonicalForm = canonicalForm;
  }

  /**
   * Returns a {@code HostSpecifier} built from the provided {@code specifier}, which is already
   * known to be valid. If the {@code specifier} might be invalid, use {@link #from(String)}
   * instead.
   *
   * <p>The specifier must be in one of these formats:
   *
   * <ul>
   *   <li>A domain name, like {@code google.com}

	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) {

    }

    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:

from typing import Annotated, Optional

import pytest
from fastapi import FastAPI, Form
from fastapi.testclient import TestClient
from pydantic import BaseModel, Field

from .utils import get_body_model_name

app = FastAPI()

# =====================================================================================
# Without aliases


@app.post("/optional-str", operation_id="optional_str")

    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() {

from base64 import b64encode
from typing import Optional

from fastapi import FastAPI, Security
from fastapi.security import HTTPBasic, HTTPBasicCredentials
from fastapi.testclient import TestClient

app = FastAPI()

security = HTTPBasic(auto_error=False)


@app.get("/users/me")
def read_current_user(credentials: Optional[HTTPBasicCredentials] = Security(security)):
    if credentials is None:

from typing import Optional

import pytest
from fastapi import FastAPI
from fastapi.exceptions import ResponseValidationError
from fastapi.testclient import TestClient
from pydantic.dataclasses import dataclass

app = FastAPI()


@dataclass
class Item:
    name: str
    price: Optional[float] = None
    owner_ids: Optional[list[int]] = None


@app.get("/items/invalid", response_model=Item)
def get_invalid():