add test cases

packages/remark-growi-plugin/test/micromark-extension-growi-plugin.test.js

@@ -793,6 +793,12 @@ test('micromark-extension-directive (compile)', (t) => {
         'a $lsx(num=1)',
         'a $lsx(/)',
         'a $lsx(💚)',
+        'Leaf:',
+        '$lsx',
+        '$lsx()',
+        '$lsx(num=1)',
+        '$lsx(/)',
+        '$lsx(💚)',
       ].join('\n\n'),
       options({ lsx }),
     ),
@@ -803,6 +809,12 @@ test('micromark-extension-directive (compile)', (t) => {
       '<p>a <lsx num="1"></lsx></p>',
       '<p>a <lsx prefix="/"></lsx></p>',
       '<p>a <lsx prefix="💚"></lsx></p>',
+      '<p>Leaf:</p>',
+      '<lsx ></lsx>',
+      '<lsx ></lsx>',
+      '<lsx num="1"></lsx>',
+      '<lsx prefix="/"></lsx>',
+      '<lsx prefix="💚"></lsx>',
     ].join('\n'),
     'should support directives (lsx)',
   );