Add Group, Limit, Map, Sort functions

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

tests/Function/GroupFunctionTest.php

@@ -0,0 +1,18 @@
+<?php
+declare(strict_types=1);
+
+use Arendsen\FluxQueryBuilder\Function\Group;
+use PHPUnit\Framework\TestCase;
+
+final class GroupFunctionTest extends TestCase {
+
+    public function testSimpleGroup()
+    {
+        $expression = new Group(['foo', 'bar'], 'by');
+
+        $query = '|> group(columns: ["foo", "bar"], mode: "by") ';
+
+        $this->assertEquals($query, $expression->__toString());
+    }
+
+}

tests/Function/LimitFunctionTest.php

@@ -0,0 +1,18 @@
+<?php
+declare(strict_types=1);
+
+use Arendsen\FluxQueryBuilder\Function\Limit;
+use PHPUnit\Framework\TestCase;
+
+final class LimitFunctionTest extends TestCase {
+
+    public function testSimpleLimit()
+    {
+        $expression = new Limit(1);
+
+        $query = '|> limit(n:1) ';
+
+        $this->assertEquals($query, $expression->__toString());
+    }
+
+}

tests/Function/MapFunctionTest.php

@@ -0,0 +1,18 @@
+<?php
+declare(strict_types=1);
+
+use Arendsen\FluxQueryBuilder\Function\Map;
+use PHPUnit\Framework\TestCase;
+
+final class MapFunctionTest extends TestCase {
+
+    public function testSimpleMap()
+    {
+        $expression = new Map('r with name: r.user');
+
+        $query = '|> map(fn: (r) => ({ r with name: r.user })) ';
+
+        $this->assertEquals($query, $expression->__toString());
+    }
+
+}

tests/Function/SortFunctionTest.php

@@ -0,0 +1,18 @@
+<?php
+declare(strict_types=1);
+
+use Arendsen\FluxQueryBuilder\Function\Sort;
+use PHPUnit\Framework\TestCase;
+
+final class SortFunctionTest extends TestCase {
+
+    public function testSimpleSort()
+    {
+        $expression = new Sort(['foo', 'bar'], true);
+
+        $query = '|> sort(columns: ["foo", "bar"], desc: true) ';
+
+        $this->assertEquals($query, $expression->__toString());
+    }
+
+}