## Ajouter des validations par expressions régulières

On peut définir une <abbr title="Une expression régulière, regex ou regexp est une suite de caractères qui définit un pattern de correspondance pour les chaînes de caractères.">expression régulière</abbr> à laquelle le paramètre doit correspondre :

{* ../../docs_src/query_params_str_validations/tutorial004.py hl[10] *}

Create functions with a name that starts with `test_` (this is standard `pytest` conventions).

Use the `TestClient` object the same way as you do with `httpx`.

Write simple `assert` statements with the standard Python expressions that you need to check (again, standard `pytest`).

```Python hl_lines="2  12  15-18"
{!../../docs_src/app_testing/tutorial001.py!}
```

/// tip

 *       the {@code Converter} type using a mocking framework.
 *   <li>Extend this class and implement its {@link #doForward} and {@link #doBackward} methods.
 *   <li><b>Java 8+ users:</b> you may prefer to pass two lambda expressions or method references to
 *       the {@link #from from} factory method.
 * </ul>
 *
 * <p>Using a converter:
 *
 * <ul>
 *   <li>Convert one instance in the "forward" direction using {@code converter.convert(a)}.

  // optional DNS subdomain prefix and '/' (e.g. 'example.com/MyName')
  //
  // Required.
  optional string name = 1;

  // Expression represents the expression which will be evaluated by CEL. Must evaluate to bool.
  // CEL expressions have access to the contents of the AdmissionRequest and Authorizer, organized into CEL variables:
  //

   * in preference if at least one of the parameters is known to contain only ASCII characters.
   *
   * <p>Note however that this method does not always behave identically to expressions such as:
   *
   * <ul>
   *   <li>{@code string.toUpperCase().equals("UPPER CASE ASCII")}
   *   <li>{@code string.toLowerCase().equals("lower case ascii")}
   * </ul>
   *

     / __/__  ___ _____/ /__
    _\ \/ _ \/ _ `/ __/  '_/
   /___/ .__/\_,_/_/ /_/\_\   version 2.1.0.2.6.0.0-598
      /_/

Using Scala version 2.11.8 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_112)
Type in expressions to have them evaluated.
Type :help for more information.

scala>
```

- At the _scala>_ prompt, submit the job by typing the following commands, Replace node names, file name, and file location with your values:

          </description>
        </field>
        <field>
          <name>expression</name>
          <version>2.0.0+</version>
          <type>String</type>
          <description>Parameter expression, to let user override default value with a user property, system property or project property.</description>
        </field>
        <field>

  // the affinity expressions specified by this field, but it may choose
  // a node that violates one or more of the expressions. The node that is
  // most preferred is the one with the greatest sum of weights, i.e.
  // for each node that meets all of the scheduling requirements (resource
  // request, requiredDuringScheduling affinity expressions, etc.),

	)

	// optimize match english letters and midline
	// The following code is basically called in for.
	// In order to avoid the performance problems caused by repeated compilation of regular expressions,
	// it only needs to be done once outside, so optimization is done here.
	if idx != -1 && regEnLetterAndMidline.MatchString(str[0:idx]) {
		name = str[0:idx]
	} else {

		Description:    "Did not find the expected identifier for AT name in the SQL expression.",
		HTTPStatusCode: http.StatusBadRequest,
	},
	ErrParseAsteriskIsNotAloneInSelectList: {
		Code:           "ParseAsteriskIsNotAloneInSelectList",
		Description:    "Other expressions are not allowed in the SELECT list when '*' is used without dot notation in the SQL expression.",
		HTTPStatusCode: http.StatusBadRequest,
	},