🐛 config.theme.timezone must not be overwritten (TryGhost#7232)

closes TryGhost#7182

When calling `config.set()` in the settings api, we want to set the active timezone of the blog to make it available in our `settingsCache`. But because the `theme` object in the `set` prototype was already set to `Etc/UTC` as default, the `_.merge` function would always overwrite our `activeTimezone` with the default value.

This PR changes the code in the way, that we always set 'Etc/UTC' for the timezone as default, _until_ we fetched our settings and therefore the `activeTimezone` setting, so we can overwrite it.

This issue had not only influence on the date helper, but everywhere in our codebase, where we rely on reading the `timezone` from our config, instead of our settings. The `{{@blog.timezone}}` helper reflected that quiet well, as it would always show `Etc/UTC`

core/server/config/index.js

@@ -118,6 +118,15 @@ ConfigManager.prototype.set = function (config) {
         this._config.theme.navigation = config.theme.navigation;
     }
 
+    // Special case for theme.timezone, which should be overridden not merged
+    if (config && config.theme && config.theme.timezone) {
+        this._config.theme.timezone = config.theme.timezone;
+    } else {
+        // until we have set the timezone from settings, we use the default
+        this._config.theme = this._config.theme ? this._config.theme : {};
+        this._config.theme.timezone = 'Etc/UTC';
+    }
+
     // Protect against accessing a non-existant object.
     // This ensures there's always at least a paths object
     // because it's referenced in multiple places.
@@ -201,10 +210,7 @@ ConfigManager.prototype.set = function (config) {
         },
         theme: {
             // normalise the URL by removing any trailing slash
-            url: this._config.url ? this._config.url.replace(/\/$/, '') : '',
-
-            // default timezone
-            timezone: 'Etc/UTC'
+            url: this._config.url ? this._config.url.replace(/\/$/, '') : ''
         },
         routeKeywords: {
             tag: 'tag',

core/test/unit/config_spec.js

@@ -36,7 +36,8 @@ describe('Config', function () {
                     title: 'casper',
                     description: 'casper',
                     logo: 'casper',
-                    cover: 'casper'
+                    cover: 'casper',
+                    timezone: 'Etc/UTC'
                 }
             });
         });
@@ -57,6 +58,35 @@ describe('Config', function () {
             themeConfig.should.have.property('description', 'casper');
             themeConfig.should.have.property('logo', 'casper');
             themeConfig.should.have.property('cover', 'casper');
+            themeConfig.should.have.property('timezone', 'Etc/UTC');
+        });
+    });
+
+    describe('Timezone default', function () {
+        it('should use timezone from settings when set', function () {
+            var themeConfig = config.theme;
+
+            // Check values are as we expect
+            themeConfig.should.have.property('timezone', 'Etc/UTC');
+            themeConfig.should.have.property('url');
+
+            configUtils.set({
+                theme: {
+                    timezone: 'Africa/Cairo'
+                }
+            });
+
+            config.theme.should.have.property('timezone', 'Africa/Cairo');
+            config.theme.should.have.property('url');
+        });
+
+        it('should set theme object with timezone by default', function () {
+            var themeConfig = configUtils.defaultConfig;
+
+            // Check values are as we expect
+            themeConfig.should.have.property('theme');
+            themeConfig.theme.should.have.property('timezone', 'Etc/UTC');
+            themeConfig.theme.should.have.property('url');
         });
     });