Update Min & Max function to compare with null values.

src/Processor/Expression/FunctionEvaluator.php

@@ -435,14 +435,20 @@ private static function sqlMin(
 
             $value = Evaluator::evaluate($conn, $scope, $expr, $row, $result);
 
-            if (!\is_scalar($value)) {
+            if (!\is_scalar($value) && !\is_null($value)) {
                 throw new \TypeError('Bad min value');
             }
 
             $values[] = $value;
         }
 
-        return self::castAggregate(\min($values), $expr, $result);
+        $min_value = \min($values);
+
+        if ($min_value === null) {
+            return null;
+        }
+
+        return self::castAggregate($min_value, $expr, $result);
     }
 
     /**
@@ -470,14 +476,20 @@ private static function sqlMax(
 
             $value = Evaluator::evaluate($conn, $scope, $expr, $row, $result);
 
-            if (!\is_scalar($value)) {
+            if (!\is_scalar($value) && !\is_null($value)) {
                 throw new \TypeError('Bad max value');
             }
 
             $values[] = $value;
         }
 
-        return self::castAggregate(\max($values), $expr, $result);
+        $max_value = \max($values);
+
+        if ($max_value === null) {
+            return null;
+        }
+
+        return self::castAggregate($max_value, $expr, $result);
     }
 
     /**

tests/FunctionEvaluatorTest.php

@@ -0,0 +1,122 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Vimeo\MysqlEngine\Tests;
+
+use PHPUnit\Framework\TestCase;
+
+class FunctionEvaluatorTest extends TestCase
+{
+
+    public function tearDown() : void
+    {
+        \Vimeo\MysqlEngine\Server::reset();
+    }
+
+    /**
+     * @dataProvider maxValueProvider
+     */
+    public function testSqlMax(string $sql, ?string $expected, bool $is_db_number) : void
+    {
+        $query = self::getConnectionToFullDB()->prepare($sql);
+        $query->execute();
+        /** @var array<array<string, string|null>> $result */
+        $result = $query->fetchAll(\PDO::FETCH_ASSOC);
+
+        if ($is_db_number) {
+            $this->assertNotEmpty($result);
+            $this->assertNotNull($result[0]['max']);
+        } else {
+            $this->assertSame([['max' => $expected]], $result);
+        }
+    }
+
+    public static function maxValueProvider(): array
+    {
+        return [
+            'null when no rows' => [
+                'sql' => 'SELECT MAX(null) as `max` FROM `video_game_characters`',
+                'expected' => null,
+                'is_db_number' => false,
+            ],
+            'max of scalar values' => [
+                'sql' => 'SELECT MAX(10) as `max` FROM `video_game_characters`',
+                'expected' => '10',
+                'is_db_number' => false,
+            ],
+            'max in DB values' => [
+                'sql' => 'SELECT MAX(id) as `max` FROM `video_game_characters`',
+                'expected' => '',
+                'is_db_number' => true,
+            ],
+        ];
+    }
+
+    /**
+     * @dataProvider minValueProvider
+     */
+    public function testSqlMin(string $sql, ?string $expected, bool $is_db_number) : void
+    {
+        $query = self::getConnectionToFullDB()->prepare($sql);
+        $query->execute();
+        /** @var array<array<string, string|null>> $result */
+        $result = $query->fetchAll(\PDO::FETCH_ASSOC);
+
+        if ($is_db_number) {
+            $this->assertNotEmpty($result);
+            $this->assertNotNull($result[0]['min']);
+        } else {
+            $this->assertSame([['min' => $expected]], $result);
+        }
+    }
+
+    public static function minValueProvider(): array
+    {
+        return [
+            'null when no rows' => [
+                'sql' => 'SELECT MIN(null) as `min` FROM `video_game_characters`',
+                'expected' => null,
+                'is_db_number' => false,
+            ],
+            'min of scalar values' => [
+                'sql' => 'SELECT MIN(10) as `min` FROM `video_game_characters`',
+                'expected' => '10',
+                'is_db_number' => false,
+            ],
+            'min in DB values' => [
+                'sql' => 'SELECT MIN(id) as `min` FROM `video_game_characters`',
+                'expected' => '',
+                'is_db_number' => true,
+            ],
+        ];
+    }
+
+    private static function getPdo(string $connection_string, bool $strict_mode = false) : \PDO
+    {
+        $options = $strict_mode ? [\PDO::MYSQL_ATTR_INIT_COMMAND => 'SET sql_mode="STRICT_ALL_TABLES"'] : [];
+
+        if (\PHP_MAJOR_VERSION === 8) {
+            return new \Vimeo\MysqlEngine\Php8\FakePdo($connection_string, '', '', $options);
+        }
+
+        return new \Vimeo\MysqlEngine\Php7\FakePdo($connection_string, '', '', $options);
+    }
+
+    private static function getConnectionToFullDB(bool $emulate_prepares = true, bool $strict_mode = false) : \PDO
+    {
+        $pdo = self::getPdo('mysql:foo;dbname=test;', $strict_mode);
+
+        $pdo->setAttribute(\PDO::ATTR_EMULATE_PREPARES, $emulate_prepares);
+
+        // create table
+        $pdo->prepare(file_get_contents(__DIR__ . '/fixtures/create_table.sql'))->execute();
+
+        // insertData
+        $pdo->prepare(file_get_contents(__DIR__ . '/fixtures/bulk_character_insert.sql'))->execute();
+        $pdo->prepare(file_get_contents(__DIR__ . '/fixtures/bulk_enemy_insert.sql'))->execute();
+        $pdo->prepare(file_get_contents(__DIR__ . '/fixtures/bulk_tag_insert.sql'))->execute();
+
+        return $pdo;
+    }
+}