What

Fixes test_card_block_renders_with_background_color which started failing on WordPress 7.0.

Why

WordPress core ticket #64531 corrected a bug in build_visual_html_tree() (the function powering assertEqualHTML). The function was incorrectly trimming leading whitespace from text nodes, including whitespace-only text nodes between elements. The fix shipped in WP 6.9.1 and is included in WP 7.0.

Before the fix, this $expected string passed silently:

$expected = '
    <div class="...">
        <p>Hello</p>
    </div>
';

Even though the actual output had no whitespace text nodes between elements, the leading newline and the tabs between <div> and <p> were being stripped from the tree, so the comparison appeared equal.

After the fix, those whitespace-only text nodes are preserved and compared — correctly causing the assertion to fail when the actual output has no such nodes.

The fix

• Remove the leading newline before <div> in $expected.
• Remove the whitespace between the closing > of the opening tag and <p>, and between </p> and </div>.
• Attributes can still span multiple lines for readability — whitespace inside an opening tag is not a text node.

Updated the docblock to document this behaviour as a learning point for readers of these examples.

Also bumps .wp-env.json to wordpress-7.0-beta1 to match the version under test.

Key rule going forward

Whitespace between elements in $expected creates text nodes that must match the actual output. If the render function produces <div><p>...</p></div> (no gaps), the expected string must do the same. Attributes on separate lines are fine.

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