test(core): unit tests for Util/Database/Enum pure logic (+44 tests)

Adds tests for Encryption, TimeUtils, QueryHelper, AdminHelpers, ImageUtils,
StreamUtils and BootContext/ServerEnvironment enums. 242 -> 286 tests, all green.

tests/Unit/QueryHelperTest.php

@@ -0,0 +1,40 @@
+<?php
+
+use PHPUnit\Framework\TestCase;
+
+/**
+ * @covers QueryHelper
+ */
+final class QueryHelperTest extends TestCase {
+
+	public function testPrepareColumnSanitizesToSafeIdentifier() {
+		$this->assertSame('foobar23', QueryHelper::prepareColumn('Foo Bar!23'));
+		$this->assertSame('user_id', QueryHelper::prepareColumn('user_id'));
+		$this->assertSame('droptable', QueryHelper::prepareColumn('drop;table'));
+	}
+
+	public function testPrepareArrayBuildsColumnsPlaceholdersAndData() {
+		$result = QueryHelper::prepareArray(array('name' => 'x', 'age' => 5));
+
+		$this->assertSame('`name`,`age`', $result['columns']);
+		$this->assertSame('?,?', $result['placeholder']);
+		$this->assertSame(array('x', 5), $result['data']);
+		$this->assertSame('`name` = ?,`age` = ?', $result['update']);
+	}
+
+	public function testPrepareArrayJsonEncodesArrayValues() {
+		$result = QueryHelper::prepareArray(array('tags' => array(1, 2, 3)));
+		$this->assertSame('[1,2,3]', $result['data'][0]);
+	}
+
+	public function testPrepareArrayNormalizesNullValues() {
+		$result = QueryHelper::prepareArray(array('a' => null, 'b' => 'null'));
+		$this->assertNull($result['data'][0]);
+		$this->assertNull($result['data'][1]);
+	}
+
+	public function testPrepareArraySanitizesColumnNames() {
+		$result = QueryHelper::prepareArray(array('na me!' => 'v'));
+		$this->assertSame('`name`', $result['columns']);
+	}
+}