Fix existing tests, added tests for spoilers, and adjusted spoiler logic

[hjiangsu]

This PR contains the following changes:

• Fixed all existing tests that were failing
• Added some spoiler tests for formatting to markdown, and widget tests
• Adjusted some of the logic for how spoilers are created. This is to allow inline selection of content to create spoilers
  • Additionally, I've adjusted to cursor positioning so that the cursor lands at the end of the spoiler body

ecdb9a7f-2320-4b72-aaf3-41a1bd1300dd.mp4

[micahmo]

LGTM!

• Adjusted some of the logic for how spoilers are created. This is to allow inline selection of content to create spoilers
  • Additionally, I've adjusted to cursor positioning so that the cursor lands at the end of the spoiler body

Just curious, but was there a regression? Looking back at the demo in #6 both of these things worked.

[hjiangsu]

Just curious, but was there a regression? Looking back at the demo in #6 both of these things worked.

selection of content to create spoilers

For this, I believe it was creating the spoiler on the same line which would be invalid!

This is some text ::: spoiler Spoiler
spoiler body
:::

The correct behaviour should be

This is some text
::: spoiler Spoiler
spoiler body
:::

cursor positioning so that the cursor lands at the end of the spoiler body

Trying this again, I cant reproduce my issue. However, I encountered a case previously where it was not inserting the cursor at the right location (it seems like it had something to do with selectedText being an empty string)

[hjiangsu]

I also added a commit which fixes a couple more edge cases that I found!

487b6002-8296-4ce1-8432-b38251006457.mp4

[micahmo]

Cool, thanks! Looks good!