fix: paste tables into document

Fixes #2708.

Try to read the first table row as headings.

Pasting works via `insertContent` while opening uses `setContent`.
They use the schema in different ways.
So we also need to make sure to test both for some corner cases.

`setContent` is fairly flexible in turning the input
into a valid document structure.
`insertContent` however fails to resolve structures
that would require picking lower priority parent elements.

Note: Some tests in src/tests/nodes/Table.spec.js
fail when using `insertContent` instead of `setContent`.
Pasting the correponding html table is fixed never the less.

Signed-off-by: Max <max@nextcloud.com>
Signed-off-by: Jonas <jonas@freesources.org>

src/nodes/Table/TableHeadRow.js

@@ -18,7 +18,7 @@ export default TableRow.extend({
 
 	parseHTML() {
 		return [
-			{ tag: 'tr', priority: 70 },
+			{ tag: 'tr:first-of-type', priority: 80 },
 		]
 	},
 })

src/nodes/Table/TableRow.js

@@ -11,7 +11,7 @@ export default TableRow.extend({
 
 	parseHTML() {
 		return [
-			{ tag: 'tr', priority: 80 },
+			{ tag: 'tr', priority: 70 },
 		]
 	},
 })

src/tests/markdown.spec.js

@@ -22,6 +22,15 @@ const markdownThroughEditorHtml = (html) => {
 	return serializer.serialize(tiptap.state.doc)
 }
 
+const markdownFromPaste = (html) => {
+	const tiptap = createEditor({
+		content: html,
+		enableRichEditing: true
+	})
+	const serializer = createMarkdownSerializer(tiptap.schema)
+	return serializer.serialize(tiptap.state.doc)
+}
+
 describe('Commonmark', () => {
 	beforeAll(() => {
 		// Make sure html tests pass
@@ -242,11 +251,20 @@ describe('Markdown serializer from html', () => {
 		)).toBe(`::: warn\n!warning!\n\n:::`)
 	})
 
+	test('table', () => {
+		expect(markdownThroughEditorHtml('<table><tbody><tr><th>greetings</th></tr><tr><td>hello</td></tr></tbody></table>')).toBe('| greetings |\n|-----------|\n| hello |\n')
+	})
+
 	test('table cell escaping', () => {
 		// while '|' has no special meaning in commonmark is has to be escaped for GFM tables
 		expect(markdownThroughEditorHtml('<table><tr><th>greetings</th></tr><tr><td>hello | hallo</td></tr></table>')).toBe('| greetings |\n|-----------|\n| hello \\| hallo |\n')
 	})
 
+	test('table pastes (#2708)', () => {
+		// while '|' has no special meaning in commonmark is has to be escaped for GFM tables
+		expect(markdownFromPaste('<table><tbody><tr><th>greetings</th></tr><tr><td>hello</td></tr></tbody></table>')).toBe('| greetings |\n|-----------|\n| hello |\n')
+	})
+
 	test('front matter', () => {
 		expect(markdownThroughEditorHtml('<pre id="frontmatter"><code>some: value</code></pre><h1>Heading</h1>')).toBe('---\nsome: value\n---\n\n# Heading')
 		// Test --- within front matter is allowed