Migrate preformatted block tests to Playwright (#41128)

* Add preformatted block tests

* await page.click( 'role=button[name="Add default block"i]' );

* Update preformatted.spec.js

Author: JustinyAhin

packages/e2e-tests/specs/editor/blocks/__snapshots__/preformatted.test.js.snap

@@ -0,0 +1,4 @@
+<!-- wp:html -->
+<pre>1
+2</pre>
+<!-- /wp:html -->

packages/e2e-tests/specs/editor/blocks/preformatted.test.js

@@ -0,0 +1,5 @@
+<!-- wp:preformatted -->
+<pre class="wp-block-preformatted">0
+1
+2</pre>
+<!-- /wp:preformatted -->

test/e2e/specs/editor/blocks/__snapshots__/Preformatted-should-preserve-character-newlines-1-chromium.txt

@@ -0,0 +1,5 @@
+<!-- wp:preformatted -->
+<pre class="wp-block-preformatted">1
+2
+3</pre>
+<!-- /wp:preformatted -->

test/e2e/specs/editor/blocks/__snapshots__/Preformatted-should-preserve-character-newlines-2-chromium.txt

@@ -0,0 +1,59 @@
+/**
+ * WordPress dependencies
+ */
+const { test, expect } = require( '@wordpress/e2e-test-utils-playwright' );
+
+test.describe( 'Preformatted', () => {
+	test.beforeEach( async ( { admin } ) => {
+		await admin.createNewPost();
+	} );
+
+	test( 'should preserve character newlines', async ( { editor, page } ) => {
+		await editor.insertBlock( { name: 'core/html' } );
+		await page.keyboard.type( '<pre>1' );
+		await page.keyboard.press( 'Enter' );
+		await page.keyboard.type( '2</pre>' );
+
+		expect( await editor.getEditedPostContent() ).toMatchSnapshot();
+
+		await editor.clickBlockOptionsMenuItem( 'Convert to Blocks' );
+		// Once it's edited, it should be saved as BR tags.
+		await page.keyboard.type( '0' );
+		await page.keyboard.press( 'Enter' );
+		await editor.clickBlockOptionsMenuItem( 'Edit as HTML' );
+
+		expect( await editor.getEditedPostContent() ).toMatchSnapshot();
+	} );
+
+	test( 'should preserve white space when merging', async ( {
+		editor,
+		page,
+	} ) => {
+		await editor.insertBlock( { name: 'core/preformatted' } );
+		await page.keyboard.type( '1' );
+		await page.keyboard.press( 'Enter' );
+		await page.keyboard.type( '2' );
+		await page.keyboard.press( 'Enter' );
+		await editor.insertBlock( { name: 'core/paragraph' } );
+		await page.keyboard.type( '3' );
+		await page.keyboard.press( 'ArrowLeft' );
+		await page.keyboard.press( 'Backspace' );
+
+		expect( await editor.getEditedPostContent() ).toMatchSnapshot();
+	} );
+
+	test( 'should delete block when backspace in an empty preformatted', async ( {
+		editor,
+		page,
+	} ) => {
+		await editor.insertBlock( { name: 'core/preformatted' } );
+
+		await page.keyboard.type( 'a' );
+
+		await page.keyboard.press( 'Backspace' );
+		await page.keyboard.press( 'Backspace' );
+
+		// Expect preformatted block to be deleted.
+		expect( await editor.getEditedPostContent() ).toBe( '' );
+	} );
+} );