From 1c10c542f324b285e1326120e3c368e932746e75 Mon Sep 17 00:00:00 2001
From: Michael Hawkins <michaelh@moodle.com>
Date: Tue, 26 Nov 2019 16:24:59 +0800
Subject: [PATCH 1/2] MDL-67364 output: Allow child themes to use parent
 editor_scss config

This still allows child themes to override editor_scss, but will fall
back to what the parent is using if they do not specify it. This
negates the need for every child them to have the config duplicated
in order to utilise it.
---
 lib/outputlib.php | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/lib/outputlib.php b/lib/outputlib.php
index 56a1110b15d..d50d022a9b9 100644
--- a/lib/outputlib.php
+++ b/lib/outputlib.php
@@ -961,12 +961,31 @@ class theme_config {
      */
     public function editor_scss_to_css() {
         $css = '';
+        $dir = $this->dir;
+        $filenames = [];
 
+        // Use editor_scss file(s) provided by this theme if set.
         if (!empty($this->editor_scss)) {
+            $filenames = $this->editor_scss;
+        } else {
+            // If no editor_scss set, move up theme hierarchy until one is found (if at all).
+            // This is so child themes only need to set editor_scss if an override is required.
+            foreach (array_reverse($this->parent_configs) as $parentconfig) {
+                if (!empty($parentconfig->editor_scss)) {
+                    $dir = $parentconfig->dir;
+                    $filenames = $parentconfig->editor_scss;
+
+                    // Config found, stop looking.
+                    break;
+                }
+            }
+        }
+
+        if (!empty($filenames)) {
             $compiler = new core_scss();
 
-            foreach ($this->editor_scss as $filename) {
-                $compiler->set_file("{$this->dir}/scss/{$filename}.scss");
+            foreach ($filenames as $filename) {
+                $compiler->set_file("{$dir}/scss/{$filename}.scss");
 
                 try {
                     $css .= $compiler->to_css();

From 2c78a8f479e3c96591826d849f775299e9637357 Mon Sep 17 00:00:00 2001
From: Michael Hawkins <michaelh@moodle.com>
Date: Thu, 13 Feb 2020 17:20:32 +0800
Subject: [PATCH 2/2] MDL-67364 output: Add unit testing for editor_scss_to_css

---
 lib/tests/theme_config_test.php | 38 +++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/lib/tests/theme_config_test.php b/lib/tests/theme_config_test.php
index 85945c41cd0..35f3df73c63 100644
--- a/lib/tests/theme_config_test.php
+++ b/lib/tests/theme_config_test.php
@@ -175,4 +175,42 @@ class core_theme_config_testcase extends advanced_testcase {
 
         $this->assertRegExp("/{$themerevision}_{$themesubrevision}/", $url->out(false));
     }
+
+    /**
+     * Confirm that editor_scss_to_css is correctly compiling for themes with no parent.
+     */
+    public function test_editor_scss_to_css_root_theme() {
+        global $CFG;
+
+        $this->resetAfterTest();
+        $theme = theme_config::load('boost');
+        $editorscss = $CFG->dirroot.'/theme/boost/scss/editor.scss';
+
+        $this->assertTrue(file_exists($editorscss));
+        $compiler = new core_scss();
+        $compiler->set_file($editorscss);
+        $cssexpected = $compiler->to_css();
+        $cssactual = $theme->editor_scss_to_css();
+
+        $this->assertEquals($cssexpected, $cssactual);
+    }
+
+    /**
+     * Confirm that editor_scss_to_css is compiling for a child theme not overriding its parent's editor SCSS.
+     */
+    public function test_editor_scss_to_css_child_theme() {
+        global $CFG;
+
+        $this->resetAfterTest();
+        $theme = theme_config::load('classic');
+        $editorscss = $CFG->dirroot.'/theme/boost/scss/editor.scss';
+
+        $this->assertTrue(file_exists($editorscss));
+        $compiler = new core_scss();
+        $compiler->set_file($editorscss);
+        $cssexpected = $compiler->to_css();
+        $cssactual = $theme->editor_scss_to_css();
+
+        $this->assertEquals($cssexpected, $cssactual);
+    }
 }