Add field match enum

tests/unit/FieldMatchTest.php

@@ -0,0 +1,22 @@
+<?php declare(strict_types=1);
+
+namespace Test\Unit;
+
+use BitBadger\PDODocument\FieldMatch;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Unit tests for the FieldMatch enum
+ */
+class FieldMatchTest extends TestCase
+{
+    public function testToStringSucceedsForAll(): void
+    {
+        $this->assertEquals('AND', FieldMatch::All->toString(), 'All should have returned AND');
+    }
+
+    public function testToStringSucceedsForAny(): void
+    {
+        $this->assertEquals('OR', FieldMatch::Any->toString(), 'Any should have returned OR');
+    }
+}