Any guides for testing with this thing?

I'm wanting to write some tests against our our customised version of this tool. I'm having trouble with both Testing Library and Cypress.

With testing library - I can do this:

```
userEvent.type(screen.getByRole("textbox"), "some plain text");
```

But I can't test keyboard short cuts like:

```
userEvent.type(screen.getByRole("textbox"), "hello{meta}b{meta/}world")

```

With cypress I'm finding that I can enter text like:

```
cy.get('.CodeMirror').type(
"aaa"
);
```

Also:

```
cy.get('.CodeMirror').type(
"hello{meta+b}world"
);
```

Any other guides/best practises for testing?

Review the existing guidance and test setup for Testing Library, Cypress, and the CodeMirror editor. Document supported approaches for entering text and testing keyboard shortcuts, including the examples in the issue, and make the guide clear enough for users testing customized versions of the editor.

Written by the indexing model from the issue text.