add test

docs/src/demos/Nodes/CodeBlock/index.spec.js

@@ -167,4 +167,19 @@ context('/demos/Nodes/CodeBlock', () => {
         .should('not.exist')
     })
   })
+
+  it.only('removes the code block when pressing backspace, even at start of document', () => {
+    cy.get('.ProseMirror').then(([{ editor }]) => {
+      editor.commands.clearContent()
+
+      cy.get('.ProseMirror pre')
+        .should('not.exist')
+
+      cy.get('.ProseMirror')
+        .type('``` A{leftArrow}{backspace}')
+
+      cy.get('.ProseMirror pre')
+        .should('not.exist')
+    })
+  })
 })