minor #21090 [JsonPath] Add test documentation for the component (vinceAmstoutz)

This PR was squashed before being merged into the 7.3 branch.

Discussion
----------

[JsonPath] Add test documentation for the component

Updates the documentation to document `JsonPathAssertionsTrait` and related constraints (closes #20977).

Complete the previous work done in #21078.

Commits
-------

87ccbb5 [JsonPath] Add test documentation for the component

Author: javiereguiluz

components/json_path.rst

@@ -30,9 +30,9 @@ You can install the component in your project using Composer:
 Usage
 -----
 
-To start querying a JSON document, first create a :class:`Symfony\\Component\\JsonPath\\JsonCrawler`
-object from a JSON string. The following examples use this sample "bookstore"
-JSON data::
+To start querying a JSON document, first create a
+:class:`Symfony\\Component\\JsonPath\\JsonCrawler`object from a JSON string. The
+following examples use this sample "bookstore" JSON data::
 
     use Symfony\Component\JsonPath\JsonCrawler;
 
@@ -77,8 +77,9 @@ JSON data::
 
     $crawler = new JsonCrawler($json);
 
-Once you have the crawler instance, use its :method:`Symfony\\Component\\JsonPath\\JsonCrawler::find`
-method to start querying the data. This method returns an array of matching values.
+Once you have the crawler instance, use its
+:method:`Symfony\\Component\\JsonPath\\JsonCrawler::find` method to start
+querying the data. This method returns an array of matching values.
 
 Querying with Expressions
 -------------------------
@@ -97,9 +98,9 @@ of the document is represented by ``$``::
 
     // $titles is ['Sayings of the Century']
 
-Dot notation is the default, but JSONPath provides other syntaxes for cases where
-it doesn't work. Use bracket notation (``['...']``) when a key contains spaces
-or special characters::
+Dot notation is the default, but JSONPath provides other syntaxes for cases
+where it doesn't work. Use bracket notation (``['...']``) when a key contains
+spaces or special characters::
 
     // this is equivalent to the previous example
     $titles = $crawler->find('$["store"]["book"][0]["title"]');
@@ -119,7 +120,12 @@ you to find values without specifying the full path::
     // get all authors from anywhere in the document
     $authors = $crawler->find('$..author');
 
-    // $authors is ['Nigel Rees', 'Evelyn Waugh', 'Herman Melville', 'John Ronald Reuel Tolkien']
+    // $authors is equals to [
+        'Nigel Rees',
+        'Evelyn Waugh',
+        'Herman Melville',
+        'John Ronald Reuel Tolkien'
+    ]
 
 Filtering Results
 ~~~~~~~~~~~~~~~~~
@@ -135,8 +141,9 @@ Building Queries Programmatically
 
 For more dynamic or complex query building, use the fluent API provided
 by the :class:`Symfony\\Component\\JsonPath\\JsonPath` class. This lets you
-construct a query object step by step. The ``JsonPath`` object can then be passed
-to the crawler's :method:`Symfony\\Component\\JsonPath\\JsonCrawler::find` method.
+construct a query object step by step. The ``JsonPath`` object can then be
+passed to the crawler's
+:method:`Symfony\\Component\\JsonPath\\JsonCrawler::find` method.
 
 The main advantage of the programmatic builder is that it automatically handles
 escaping of keys and values, preventing syntax errors::
@@ -178,7 +185,8 @@ methods to build your query:
 * :method:`Symfony\\Component\\JsonPath\\JsonPath::index`
   Adds an array index selector. Index numbers start at ``0``.
 
-* :method:`Symfony\\Component\\JsonPath\\JsonPath::first` / :method:`Symfony\\Component\\JsonPath\\JsonPath::last`
+* :method:`Symfony\\Component\\JsonPath\\JsonPath::first` /
+  :method:`Symfony\\Component\\JsonPath\\JsonPath::last`
   Shortcuts for ``index(0)`` and ``index(-1)`` respectively::
 
       // get the last book: '$["store"]["book"][-1]'
@@ -213,17 +221,101 @@ filters, refer to the `Querying with Expressions`_ section above. All these
 features are supported and can be combined with the programmatic builder when
 appropriate (e.g., inside a ``filter()`` expression).
 
+Testing with JSON Assertions
+----------------------------
+
+The component provides a set of PHPUnit assertions to make testing JSON data
+more convenient. Use the
+:class:`Symfony\\Component\\JsonPath\\Test\\JsonPathAssertionsTrait`
+in your test class::
+
+    use PHPUnit\Framework\TestCase;
+    use Symfony\Component\JsonPath\Test\JsonPathAssertionsTrait;
+
+    class MyTest extends TestCase
+    {
+        use JsonPathAssertionsTrait;
+
+        public function testSomething(): void
+        {
+            $json = '{"books": [{"title": "A"}, {"title": "B"}]}';
+
+            self::assertJsonPathCount(2, '$.books[*]', $json);
+        }
+    }
+
+The trait provides the following assertion methods:
+
+* :method:`Symfony\\Component\\JsonPath\\Test\\JsonPathAssertionsTrait::assertJsonPathCount`
+  Asserts that the number of elements found by the JSONPath expression matches
+  an expected count::
+
+      $json = '{"a": [1, 2, 3]}';
+      self::assertJsonPathCount(3, '$.a[*]', $json);
+
+* :method:`Symfony\\Component\\JsonPath\\Test\\JsonPathAssertionsTrait::assertJsonPathEquals`
+  Asserts that the result of a JSONPath expression is equal to an expected
+  value. The comparison uses ``==`` (type coercion) instead of ``===``::
+
+      $json = '{"a": [1, 2, 3]}';
+
+      // passes because "1" == 1
+      self::assertJsonPathEquals(['1'], '$.a[0]', $json);
+
+* :method:`Symfony\\Component\\JsonPath\\Test\\JsonPathAssertionsTrait::assertJsonPathNotEquals`
+  Asserts that the result of a JSONPath expression is not equal to an expected
+  value. The comparison uses ``!=`` (type coercion) instead of ``!==``::
+
+      $json = '{"a": [1, 2, 3]}';
+      self::assertJsonPathNotEquals([42], '$.a[0]', $json);
+
+* :method:`Symfony\\Component\\JsonPath\\Test\\JsonPathAssertionsTrait::assertJsonPathSame`
+  Asserts that the result of a JSONPath expression is identical (``===``) to an
+  expected value. This is a strict comparison and does not perform type
+  coercion::
+
+      $json = '{"a": [1, 2, 3]}';
+
+      // fails because "1" !== 1
+      // self::assertJsonPathSame(['1'], '$.a[0]', $json);
+
+      self::assertJsonPathSame([1], '$.a[0]', $json);
+
+* :method:`Symfony\\Component\\JsonPath\\Test\\JsonPathAssertionsTrait::assertJsonPathNotSame`
+  Asserts that the result of a JSONPath expression is not identical (``!==``) to
+  an expected value::
+
+      $json = '{"a": [1, 2, 3]}';
+      self::assertJsonPathNotSame(['1'], '$.a[0]', $json);
+
+* :method:`Symfony\\Component\\JsonPath\\Test\\JsonPathAssertionsTrait::assertJsonPathContains`
+  Asserts that a given value is found within the array of results from the
+  JSONPath expression::
+
+      $json = '{"tags": ["php", "symfony", "json"]}';
+      self::assertJsonPathContains('symfony', '$.tags[*]', $json);
+
+* :method:`Symfony\\Component\\JsonPath\\Test\\JsonPathAssertionsTrait::assertJsonPathNotContains`
+  Asserts that a given value is NOT found within the array of results from the
+  JSONPath expression::
+
+      $json = '{"tags": ["php", "symfony", "json"]}';
+      self::assertJsonPathNotContains('java', '$.tags[*]', $json);
+
 Error Handling
 --------------
 
 The component throws specific exceptions for invalid input or queries:
 
 * :class:`Symfony\\Component\\JsonPath\\Exception\\InvalidArgumentException`:
-  Thrown if the input to the ``JsonCrawler`` constructor is not a valid JSON string;
+  Thrown if the input to the ``JsonCrawler`` constructor is not a valid JSON
+string;
 * :class:`Symfony\\Component\\JsonPath\\Exception\\InvalidJsonStringInputException`:
-  Thrown during a ``find()`` call if the JSON string is malformed (e.g., syntax error);
+  Thrown during a ``find()`` call if the JSON string is malformed
+(e.g., syntax error);
 * :class:`Symfony\\Component\\JsonPath\\Exception\\JsonCrawlerException`:
-  Thrown for errors within the JsonPath expression itself, such as using an unknown function
+  Thrown for errors within the JsonPath expression itself, such as using an
+  unknown function
 
 Example of handling errors::