Put selection in the single paragraph, and press code block button. Paragraph should change to code block.
Select multiple paragraphs and press code block icon. All blocks should be changed into one code block element with a multiple lines.
Change the middle paragraph into code block, select the preceding and the following paragraph, and press code block button. All selected blocks should be merged into one code block.
Try to create code block into block quote - it should work fine.
Try to create create a block quote into a table - it should work fine.