Backport JSON funcs from v2

tests/Integration/DocumentTestCase.php

@@ -0,0 +1,37 @@
+<?php
+/**
+ * @author Daniel J. Summers <daniel@bitbadger.solutions>
+ * @license MIT
+ */
+
+declare(strict_types=1);
+
+namespace Test\Integration;
+
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Base test case class for document integration tests
+ */
+class DocumentTestCase extends TestCase
+{
+    /**
+     * Clear the output buffer
+     */
+    public function clearBuffer(): void
+    {
+        ob_clean();
+        ob_start();
+    }
+
+    /**
+     * Get the contents of the output buffer and end buffering
+     *
+     * @return string The contents of the output buffer
+     */
+    public function getBufferContents(): string {
+        $contents = ob_get_contents();
+        ob_end_clean();
+        return $contents;
+    }
+}