diff --git a/.gitignore b/.gitignore
index db94f805610edf999d78e68ac5f7f7b5dcf0bff6..6b2871a2aefe4c369226d3db1d742a0b58214c29 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,5 @@
 /vendor
 /.idea
 /composer.lock
+/**/*.actual
+/**/*.expected
diff --git a/tests/optional.phpt b/tests/fn.optional.phpt
similarity index 100%
rename from tests/optional.phpt
rename to tests/fn.optional.phpt
diff --git a/tests/fn.parameters.phpt b/tests/fn.parameters.phpt
new file mode 100644
index 0000000000000000000000000000000000000000..e00071fc8b1f43a5528eea02a98c8f1b8723b4f9
--- /dev/null
+++ b/tests/fn.parameters.phpt
@@ -0,0 +1,26 @@
+<?php declare(strict_types=1);
+namespace MyTestNamespace;
+require __DIR__ . '/bootstrap.php';
+
+use function Grifart\AssertFunction\optional;
+use function Grifart\AssertFunction\parameters;
+use Tester\Assert;
+
+class TestClass {};
+
+Assert::equal(['MyTestNamespace\TestClass'], parameters(TestClass::class));
+Assert::equal([
+	'MyTestNamespace\TestClass',
+	'MyTestNamespace\TestClass'
+], parameters(
+	TestClass::class,
+	TestClass::class
+));
+
+Assert::equal([
+	'?MyTestNamespace\TestClass',
+	'MyTestNamespace\TestClass'
+], parameters(
+	optional(TestClass::class),
+	TestClass::class
+));