E2E: Add regression test for spacer block in themes without spacing units (#68913)

Co-authored-by: himanshupathak95 <[email protected]>
Co-authored-by: Mamaduka <[email protected]>
Co-authored-by: fullofcaffeine <[email protected]>

Author: 4 people

test/e2e/specs/editor/blocks/spacer.spec.js

@@ -48,4 +48,29 @@ test.describe( 'Spacer', () => {
 			)
 		).toBeFocused();
 	} );
+
+	test( 'should work in theme without spacing units support', async ( {
+		editor,
+		page,
+	} ) => {
+		await page.waitForFunction( () => window?.wp?.data );
+
+		// Mock the theme.json data to simulate a theme without spacing units
+		await page.evaluate( () => {
+			const settings = window.wp.data
+				.select( 'core/block-editor' )
+				.getSettings();
+			window.__originalSettings = settings;
+			window.wp.data.dispatch( 'core/block-editor' ).updateSettings( {
+				...settings,
+				spacing: { units: false },
+			} );
+		} );
+
+		await editor.insertBlock( { name: 'core/spacer' } );
+
+		await expect(
+			editor.canvas.locator( '.block-editor-warning' )
+		).toBeHidden();
+	} );
 } );