# Test Client - `TestClient`

You can use the `TestClient` class to test FastAPI applications without creating an actual HTTP and socket connection, just communicating directly with the FastAPI code.

Read more about it in the [FastAPI docs for Testing](https://fastapi.tiangolo.com/tutorial/testing/).

You can import it directly from `fastapi.testclient`:

```python
from fastapi.testclient import TestClient
```

{* ../../docs_src/path_params_numeric_validations/tutorial001_an_py310.py hl[10] *}

/// note | Hinweis

Ein Pfad-Parameter ist immer erforderlich, da er Teil des Pfads sein muss. Selbst wenn Sie ihn mit `None` deklarieren oder einen Defaultwert setzen, würde das nichts ändern, er wäre dennoch immer erforderlich.

///

## Die Parameter sortieren, wie Sie möchten { #order-the-parameters-as-you-need }

    /**
     * Invoked just before session is created with a mutable map that carries collected user properties so far.
     *
     * @param userProperties The mutable user properties, never {@code null}.
     * @see #contribute(ProtoSession)
     */
    default void contribute(Map<String, String> userProperties) {}

    /**

## Why is MinIO cloud-native?

// that pass integers back and forth.  No actual
// concurrency, just threads and synchronization
// and foreign code on multiple pthreads.

package main

import (
	big "."
	"runtime"
)

func fibber(c chan *big.Int, out chan string, n int64) {
	// Keep the fibbers in dedicated operating system
	// threads, so that this program tests coordination
	// between pthreads and not just goroutines.
	runtime.LockOSThread()

import org.apache.maven.model.io.ModelReader;
import org.apache.maven.model.locator.ModelLocator;
import org.eclipse.sisu.Typed;

/**
 *
 * Note: uses @Typed to limit the types it is available for injection to just ModelProcessor.
 *
 * This is because the ModelProcessor interface extends ModelLocator and ModelReader. If we
 * made this component available under all its interfaces then it could end up being injected

@Experimental
@Consumer
@Named
public interface ModelTransformer extends SpiService {

    /**
     * Apply a transformation on the file model.
     *
     * This method will be called on each file model being loaded,
     * just before validation.
     *
     * @param model the input model
     * @return the transformed model, or the input model if no transformation is needed
     * @throws ModelTransformerException
     */
    @Nonnull

         * unique within a single POM. Upon multiple declarations, 2.x just kept the last one but retained the order of
         * the first occurrence. So when we're in lenient/compat mode, we have to deal with such broken POMs and mimic
         * the way 2.x works. When we're in strict mode, the removal of duplicates just saves other merging steps from
         * aftereffects and bogus error messages.
         */

    id: context
    attributes:
      label: Context (optional)
      description: |
        How has this issue affected you? What are you trying to accomplish?
        Providing context helps us come up with a solution that is most useful in the real world
    validations:

„Asynchron“, sagt man, weil der Computer / das Programm nicht mit einer langsamen Aufgabe „synchronisiert“ werden muss und nicht auf den genauen Moment warten muss, in dem die Aufgabe beendet ist, ohne dabei etwas zu tun, um schließlich das Ergebnis der Aufgabe zu übernehmen und die Arbeit fortsetzen zu können.