diff --git a/tests/MartinGeorgiev/Doctrine/DBAL/Types/BaseTypeTest.php b/tests/MartinGeorgiev/Doctrine/DBAL/Types/BaseTypeTest.php
new file mode 100644
index 00000000..0ef5af3a
--- /dev/null
+++ b/tests/MartinGeorgiev/Doctrine/DBAL/Types/BaseTypeTest.php
@@ -0,0 +1,97 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\MartinGeorgiev\Doctrine\DBAL\Types;
+
+use Doctrine\DBAL\Platforms\AbstractPlatform;
+use MartinGeorgiev\Doctrine\DBAL\Types\BaseType;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
+
+class BaseTypeTest extends TestCase
+{
+    /**
+     * @var AbstractPlatform&MockObject
+     */
+    private AbstractPlatform $platform;
+
+    protected function setUp(): void
+    {
+        $this->platform = $this->createMock(AbstractPlatform::class);
+    }
+
+    /**
+     * @test
+     */
+    public function throws_exception_when_type_name_not_configured(): void
+    {
+        $type = new class extends BaseType {
+            protected const TYPE_NAME = '';
+        };
+
+        $this->expectException(\LogicException::class);
+        $this->expectExceptionMessage('no meaningful value for TYPE_NAME constant');
+
+        $type->getName();
+    }
+
+    /**
+     * @test
+     */
+    public function throws_exception_when_getting_sql_declaration_with_no_type_name(): void
+    {
+        $type = new class extends BaseType {
+            protected const TYPE_NAME = '';
+        };
+
+        $this->expectException(\LogicException::class);
+        $this->expectExceptionMessage('Doctrine type defined in class');
+
+        $type->getSQLDeclaration([], $this->platform);
+    }
+
+    /**
+     * @test
+     */
+    public function returns_correct_type_name(): void
+    {
+        $type = new class extends BaseType {
+            protected const TYPE_NAME = 'custom_type';
+        };
+
+        self::assertEquals('custom_type', $type->getName());
+    }
+
+    /**
+     * @test
+     */
+    public function gets_correct_sql_declaration(): void
+    {
+        $type = new class extends BaseType {
+            protected const TYPE_NAME = 'custom_type';
+        };
+
+        $this->platform
+            ->expects(self::once())
+            ->method('getDoctrineTypeMapping')
+            ->with('custom_type')
+            ->willReturn('CUSTOM_SQL_TYPE');
+
+        $result = $type->getSQLDeclaration([], $this->platform);
+        self::assertEquals('CUSTOM_SQL_TYPE', $result);
+    }
+
+    /**
+     * @test
+     */
+    public function requires_sql_comment_hint_returns_false(): void
+    {
+        $type = new class extends BaseType {
+            protected const TYPE_NAME = 'custom_type';
+        };
+
+        // @phpstan-ignore-next-line Not all Doctrine version like this method as it's deprecated. For now, we ignore the deprecation.
+        self::assertFalse($type->requiresSQLCommentHint($this->platform));
+    }
+}
diff --git a/tests/MartinGeorgiev/Doctrine/ORM/Query/AST/Functions/BaseFunctionTest.php b/tests/MartinGeorgiev/Doctrine/ORM/Query/AST/Functions/BaseFunctionTest.php
new file mode 100644
index 00000000..e9de6fd7
--- /dev/null
+++ b/tests/MartinGeorgiev/Doctrine/ORM/Query/AST/Functions/BaseFunctionTest.php
@@ -0,0 +1,97 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tests\MartinGeorgiev\Doctrine\ORM\Query\AST\Functions;
+
+use Doctrine\ORM\Query\AST\Node;
+use Doctrine\ORM\Query\SqlWalker;
+use MartinGeorgiev\Doctrine\ORM\Query\AST\Functions\BaseFunction;
+use PHPUnit\Framework\TestCase;
+
+class BaseFunctionTest extends TestCase
+{
+    /**
+     * @test
+     */
+    public function get_sql_returns_formatted_function_call(): void
+    {
+        $function = new class('test_function') extends BaseFunction {
+            // @phpstan-ignore-next-line The type for $name is not string in older Doctrine versions
+            public function __construct(string $name)
+            {
+                parent::__construct($name);
+                $this->customizeFunction();
+            }
+
+            protected function customizeFunction(): void
+            {
+                $this->setFunctionPrototype('TEST(%s, %s)');
+            }
+
+            /**
+             * @param list<Node|null> $nodes
+             */
+            public function setNodes(array $nodes): void
+            {
+                $this->nodes = $nodes;
+            }
+        };
+
+        $node1 = $this->createMock(Node::class);
+        $node1->expects($this->once())
+            ->method('dispatch')
+            ->willReturn('arg1');
+
+        $node2 = $this->createMock(Node::class);
+        $node2->expects($this->once())
+            ->method('dispatch')
+            ->willReturn('arg2');
+
+        /** @var list<Node|null> $nodes */
+        $nodes = [$node1, $node2];
+        $function->setNodes($nodes);
+
+        $sqlWalker = $this->createMock(SqlWalker::class);
+
+        $result = $function->getSql($sqlWalker);
+        $this->assertEquals('TEST(arg1, arg2)', $result);
+    }
+
+    /**
+     * @test
+     */
+    public function get_sql_handles_null_nodes(): void
+    {
+        $function = new class('test_function') extends BaseFunction {
+            // @phpstan-ignore-next-line The type for $name is not string in older Doctrine versions
+            public function __construct(string $name)
+            {
+                parent::__construct($name);
+                $this->customizeFunction();
+            }
+
+            protected function customizeFunction(): void
+            {
+                $this->setFunctionPrototype('TEST(%s)');
+            }
+
+            /**
+             * @param list<Node|null> $nodes
+             */
+            public function setNodes(array $nodes): void
+            {
+                $this->nodes = $nodes;
+            }
+        };
+
+        /** @var list<Node|null> $nodes */
+        $nodes = [null];
+        $function->setNodes($nodes);
+
+        $sqlWalker = $this->createMock(SqlWalker::class);
+
+        $result = $function->getSql($sqlWalker);
+        $this->assertEquals('TEST(null)', $result);
+    }
+}