Editor: Use a non-persistent object cache instead of transient in wp_get_global_stylesheet().

This changeset is part of a greater effort to enhance the caching strategy for theme.json based data. Similar to [55138], [55148], and [55155], the cache is currently ignored when `WP_DEBUG` is on to avoid interrupting the theme developer's workflow.

Props spacedmonkey, oandregal, flixos90, ajlende, hellofromtonya.
Fixes #57568.


git-svn-id: https://develop.svn.wordpress.org/trunk@55185 602fd350-edb4-49c9-b593-d223f7449a82

tests/phpunit/tests/theme/wpGetGlobalStylesSvgFilters.php

@@ -0,0 +1,37 @@
+<?php
+/**
+ * Tests wp_get_global_styles_svg_filters().
+ *
+ * @group themes
+ */
+class Tests_Theme_wpGetGlobalStylesSvgFilters extends WP_UnitTestCase {
+	public function set_up() {
+		parent::set_up();
+		// Clear caches.
+		wp_clean_themes_cache();
+	}
+
+	public function tear_down() {
+		wp_clean_themes_cache();
+
+		parent::tear_down();
+	}
+
+	/**
+	 * Tests that switching themes recalculates the svgs.
+	 *
+	 * @covers ::wp_get_global_styles_svg_filters
+	 *
+	 * @ticket 57568
+	 */
+	public function test_switching_themes_should_recalculate_svg() {
+		$svg_for_default_theme = wp_get_global_styles_svg_filters();
+		switch_theme( 'block-theme' );
+		$svg_for_block_theme = wp_get_global_styles_svg_filters();
+		switch_theme( WP_DEFAULT_THEME );
+
+		$this->assertStringContainsString( '<svg', $svg_for_default_theme, 'Default theme should contain SVG' );
+		$this->assertStringContainsString( '<svg', $svg_for_default_theme, 'Block theme should contain SVG' );
+		$this->assertNotSame( $svg_for_default_theme, $svg_for_block_theme, 'Cache value should have changed' );
+	}
+}