## Stripping disallowed attributes by `(insert|delete)Content` [#1088](https://github.com/ckeditor/ckeditor5-engine/issues/1088)

### Simple scenario.

1. Copy a paragraph with italic and link.
2. Paste it to the Heading 1. Inserted text should be stripped
3. Paste it to the Heading 2. Inserted text should be a link only.
4. Paste it to paragraph. Inserted text should not be stripped.

### Simple scenario (element).

1. Copy image.
2. Paste it to the editor. Image should be inserted with an alternative text "Sample image".

### Nested nodes.

1. Copy a list item with bold and link.
2. Paste it into the empty block (directly to the root) . Inserted list item should be a bold link.
2. Paste it into the empty block in BlockQuote. Inserted list item should be a bold only.

### Auto paragraphing.

1. Copy a text with bold.
2. Select all content in the editor.
3. Paste copied text. Inserted content should be a paragraph and should be stripped from bold.

### Auto paragraphing (disallowed block).

1. Copy Heading 3 with bold and italic.
2. Select all content in the editor.
3. Paste copied text. Inserted content should be a paragraph and should be stripped from bold.
