refactor: Add Equality matcher class

src/PhpPact/Consumer/Matcher/Matchers/Equality.php

@@ -0,0 +1,31 @@
+<?php
+
+namespace PhpPact\Consumer\Matcher\Matchers;
+
+use PhpPact\Consumer\Matcher\Model\MatcherInterface;
+
+/**
+ * This is the default matcher, and relies on the equals operator
+ */
+class Equality implements MatcherInterface
+{
+    /**
+     * @param object|array<mixed>|string|float|int|bool|null $value
+     */
+    public function __construct(private object|array|string|float|int|bool|null $value)
+    {
+    }
+
+    public function jsonSerialize(): object
+    {
+        return (object) [
+            'pact:matcher:type' => $this->getType(),
+            'value'             => $this->value
+        ];
+    }
+
+    public function getType(): string
+    {
+        return 'equality';
+    }
+}

src/PhpPact/Consumer/Matcher/Model/MatcherInterface.php

@@ -0,0 +1,10 @@
+<?php
+
+namespace PhpPact\Consumer\Matcher\Model;
+
+use JsonSerializable;
+
+interface MatcherInterface extends JsonSerializable
+{
+    public function getType(): string;
+}

tests/PhpPact/Consumer/Matcher/Matchers/EqualityTest.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace PhpPactTest\Consumer\Matcher\Matchers;
+
+use PhpPact\Consumer\Matcher\Matchers\Equality;
+use PHPUnit\Framework\TestCase;
+
+class EqualityTest extends TestCase
+{
+    public function testSerialize(): void
+    {
+        $string = new Equality('exact this string');
+        $this->assertSame(
+            '{"pact:matcher:type":"equality","value":"exact this string"}',
+            json_encode($string)
+        );
+    }
+}