For this test you will need two students. Create a wiki activity with Group mode set to "No groups" and Wiki mode set to collaborative.
1. Login as student1 and access a wiki activity.
2. Click the edit tab and create a new page by typing [[New page]].
3. Save the edit then click on the new page link.
4. Type some more text.
5. Login as student2 and access the wiki activity.
6. Click on the new page link then the edit tab and try editing the page. student2 should be able to edit the page.