Fix wrong namespace + Add RangeFunctionTest

Signed-off-by: davidarendsen <davidarendsen@hey.com>

tests/Functions/RangeFunctionTest.php

@@ -0,0 +1,36 @@
+<?php
+declare(strict_types=1);
+
+use Arendsen\FluxQueryBuilder\Exception\FunctionRequiredSettingMissingException;
+use Arendsen\FluxQueryBuilder\Functions\Range;
+use PHPUnit\Framework\TestCase;
+
+final class RangeFunctionTest extends TestCase {
+
+    public function testOnlyStartOption()
+    {
+        $expression = new Range(['start' => '-360h']);
+
+        $query = '|> range(start: -360h) ';
+
+        $this->assertEquals($query, $expression->__toString());
+    }
+
+    public function testWithStopOption()
+    {
+        $expression = new Range(['start' => '-360h', 'stop' => 'now()']);
+
+        $query = '|> range(start: -360h, stop: now()) ';
+
+        $this->assertEquals($query, $expression->__toString());
+    }
+
+    public function testThrowsExceptionWhenStartIsMissing()
+    {
+        $this->expectException(FunctionRequiredSettingMissingException::class);
+
+        $expression = new Range(['stop' => 'now()']);
+        $expression->__toString();
+    }
+
+}