Add test for new method

tests/DocBlock/AnnotationTest.php

@@ -342,6 +342,29 @@ public function provideTypesCases()
         ];
     }
 
+    /**
+     * @param string   $input
+     * @param string[] $expected
+     *
+     * @dataProvider provideNormalizedTypesCases
+     */
+    public function testNormalizedTypes($input, $expected)
+    {
+        $line = new Line($input);
+        $tag = new Annotation([$line]);
+
+        $this->assertSame($expected, $tag->getNormalizedTypes());
+    }
+
+    public function provideNormalizedTypesCases()
+    {
+        return [
+            ['* @param StRiNg|NuLl $foo', ['null', 'string']],
+            ['* @return Void', ['void']],
+            ['* @return Foo|Bar|Baz|Qux|null', ['bar', 'baz', 'foo', 'null', 'qux']],
+        ];
+    }
+
     public function testGetTypesOnBadTag()
     {
         $this->expectException(\RuntimeException::class);