add tests

tests/src/Core/Config/Cache/ConfigCacheTest.php

@@ -245,4 +245,34 @@ class ConfigCacheTest extends MockedTest
 
 		$this->assertEmpty($configCache->getAll());
 	}
+
+    /**
+     * Test the keyDiff() method with result
+     * @dataProvider dataTests
+     */
+	public function testKeyDiffWithResult($data)
+    {
+        $configCache = new ConfigCache($data);
+
+        $diffConfig = [
+            'fakeCat' => [
+                'fakeKey' => 'value',
+            ]
+        ];
+
+        $this->assertEquals($diffConfig, $configCache->keyDiff($diffConfig));
+    }
+
+    /**
+     * Test the keyDiff() method without result
+     * @dataProvider dataTests
+     */
+    public function testKeyDiffWithoutResult($data)
+    {
+        $configCache = new ConfigCache($data);
+
+        $diffConfig = $configCache->getAll();
+
+        $this->assertEmpty($configCache->keyDiff($diffConfig));
+    }
 }