Added visible theme errors in admin (#16081)

refs https://github.com/TryGhost/Team/issues/2393

- During boot and loading the active theme, we now cache the result of
the gscan validation. Cache configuration can happen in
`adapters.cache.gscan`
- We now also return non-fatal errors when activating or adding a theme.
- When the `themeErrorsNotification` feature flag is on, we fetch the
active theme (which includes the validation information) when loading
admin
- If the currently active theme has errors, we show an error
notification that can open the error modal
- Added a new endpoint: `/ghost/api/admin/themes/active/` that returns
the result of the last gscan validation of the active theme. If no cache
is available, it will run a new gscan validation.
- Added new permissions for the active action/endpoint (author, editor,
administrator)

ghost/admin/app/adapters/theme.js

@@ -9,4 +9,13 @@ export default class Theme extends ApplicationAdapter {
             return model;
         });
     }
+
+    active() {
+        let url = `${this.buildURL('theme', 'active')}`;
+
+        return this.ajax(url, 'GET', {data: {}}).then((data) => {
+            this.store.pushPayload('theme', data);
+            return this.store.peekAll('theme').filterBy('name', data.themes[0].name).firstObject;
+        });
+    }
 }

ghost/admin/app/components/gh-nav-menu/footer.hbs

@@ -1,11 +1,11 @@
 <div class="gh-nav-bottom">
-    {{#if (feature 'themeErrorsNotification')}}
+    {{#if (and (feature 'themeErrorsNotification') this.hasThemeErrors)}}
     <button type="button" class="gh-theme-error-toast" {{on "click" (fn this.openThemeErrors null)}}>
         <span class="gh-notification-title">Your theme contains errors</span>
         <span class="gh-theme-error-p">Some functionality on your site may be limited &rarr;</span>
     </button>
     {{/if}}
-    
+
     <div class="flex items-center justify-between">
         <div class="pe-all">
             <GhBasicDropdown @horizontalPosition="left" @verticalPosition="above" @calculatePosition={{this.userDropdownPosition}} as |dropdown|>
@@ -30,7 +30,7 @@
                             </div>
                         </li>
                         <li class="divider" role="separator"></li>
-                        
+
                         {{#if this.session.user.isContributor}}
                             <li>
                                 <LinkTo @route="posts" @query={{hash entry=null}} class="dropdown-item" @role="menuitem" tabindex="-1" data-test-nav="posts">
@@ -57,7 +57,7 @@
                                 Your profile
                             </LinkTo>
                         </li>
-                        
+
                         {{#unless this.session.user.isContributor}}
                             <li class="divider" role="separator"></li>
                             <li>
@@ -112,4 +112,4 @@
             </div>
         </div>
     </div>
-</div>
+</div>

ghost/admin/app/components/gh-nav-menu/footer.js

@@ -1,5 +1,5 @@
-import AboutModal from '../modals/theme-errors';
 import Component from '@ember/component';
+import ThemeErrorsModal from '../modals/design/theme-errors';
 import calculatePosition from 'ember-basic-dropdown/utils/calculate-position';
 import classic from 'ember-classic-decorator';
 import {action} from '@ember/object';
@@ -14,6 +14,7 @@ export default class Footer extends Component {
     @service whatsNew;
     @service feature;
     @service modals;
+    @service themeManagement;
 
     @inject config;
 
@@ -25,7 +26,17 @@ export default class Footer extends Component {
 
     @action
     openThemeErrors() {
-        this.advancedModal = this.modals.open(AboutModal);
+        this.advancedModal = this.modals.open(ThemeErrorsModal, {
+            title: 'Theme errors',
+            canActivate: false,
+            // Warnings will only be set for developers, otherwise it will always be empty
+            warnings: this.themeManagement.activeTheme.warnings,
+            errors: this.themeManagement.activeTheme.errors
+        });
+    }
+
+    get hasThemeErrors() {
+        return this.themeManagement.activeTheme && this.themeManagement.activeTheme.errors.length;
     }
 
     // equivalent to "left: auto; right: -20px"

ghost/admin/app/components/modals/theme-errors.hbs

@@ -1,22 +0,0 @@
-<div class="modal-content gh-about-modal">
-    <header class="modal-header">
-        <h1>Theme errors</h1>
-    </header>
-    <button type="button" class="close" title="Close" {{on "click" @close}}>{{svg-jar "close"}}<span class="hidden">Close</span></button>
-
-    <div class="modal-body">
-        <div>
-            <h2 class="mb0 mt4 f5 fw6">Fatal Errors</h2>
-            <p class="mb2">Must-fix to activate theme</p>
-        </div>
-
-        <div>[fatal errors placeholder]</div>
-
-        <div>
-            <h2 class="mb0 mt4 f5 fw6">Errors</h2>
-            <p class="mb2">Highly recommended to fix, functionality <strong>could</strong> be restricted</p>
-        </div>
-
-        <div>[errors placeholder]</div>
-    </div>
-</div>

ghost/admin/app/components/modals/theme-errors.js

@@ -1,7 +0,0 @@
-import Component from '@glimmer/component';
-
-export default class ThemeErrorsModal extends Component {
-    constructor() {
-        super(...arguments);
-    }
-}

ghost/admin/app/models/theme.js

@@ -4,11 +4,11 @@ import {isBlank} from '@ember/utils';
 
 export default Model.extend({
     active: attr('boolean'),
-    errors: attr('raw'),
+    errors: attr('raw', {defaultValue: () => []}),
     name: attr('string'),
     package: attr('raw'),
     templates: attr('raw', {defaultValue: () => []}),
-    warnings: attr('raw'),
+    warnings: attr('raw', {defaultValue: () => []}),
 
     customTemplates: computed('templates.[]', function () {
         let templates = this.templates || [];

ghost/admin/app/services/session.js

@@ -20,6 +20,7 @@ export default class SessionService extends ESASessionService {
     @service upgradeStatus;
     @service whatsNew;
     @service membersUtils;
+    @service themeManagement;
 
     @inject config;
 
@@ -45,6 +46,9 @@ export default class SessionService extends ESASessionService {
             this.membersUtils.fetch()
         ]);
 
+        // Theme management requires features to be loaded
+        this.themeManagement.fetch().catch(console.error); // eslint-disable-line no-console
+
         await this.frontend.loginIfNeeded();
 
         // update Sentry with the full Ghost version which we only get after authentication

ghost/admin/app/services/theme-management.js

@@ -15,6 +15,8 @@ export default class ThemeManagementService extends Service {
     @service settings;
     @service store;
     @service frontend;
+    @service session;
+    @service feature;
 
     @inject config;
 
@@ -22,6 +24,11 @@ export default class ThemeManagementService extends Service {
     @tracked previewType = 'homepage';
     @tracked previewHtml;
 
+    /**
+     * Contains the active theme object (includes warnings and errors)
+     */
+    @tracked activeTheme;
+
     allPosts = this.store.peekAll('post');
 
     availablePreviewTypes = [{
@@ -38,6 +45,20 @@ export default class ThemeManagementService extends Service {
         }).lastObject;
     }
 
+    async fetch() {
+        // contributors don't have permissions to fetch active theme
+        if (this.session.user && !this.session.user.isContributor && this.feature.get('themeErrorsNotification')) {
+            try {
+                const adapter = this.store.adapterFor('theme');
+                const activeTheme = await adapter.active();
+                this.activeTheme = activeTheme;
+            } catch (e) {
+                // We ignore these errors and log them because we don't want to block loading the app for this
+                console.error('Failed to fetch active theme', e); // eslint-disable-line no-console
+            }
+        }
+    }
+
     @action
     setPreviewType(type) {
         if (type !== this.previewType) {
@@ -90,6 +111,7 @@ export default class ThemeManagementService extends Service {
 
             try {
                 const activatedTheme = yield theme.activate();
+                this.activeTheme = activatedTheme;
 
                 yield this.customThemeSettings.reload();
 

ghost/core/core/server/api/endpoints/themes.js

@@ -4,6 +4,7 @@ const models = require('../../models');
 
 // Used to emit theme.uploaded which is used in core/server/analytics-events
 const events = require('../../lib/common/events');
+const {settingsCache} = require('../../services/settings-helpers');
 
 module.exports = {
     docName: 'themes',
@@ -15,6 +16,15 @@ module.exports = {
         }
     },
 
+    readActive: {
+        permissions: true,
+        async query() {
+            let themeName = settingsCache.get('active_theme');
+            const themeErrors = await themeService.api.getThemeErrors(themeName);
+            return themeService.api.getJSON(themeName, themeErrors);
+        }
+    },
+
     activate: {
         headers: {
             cacheInvalidate: true
@@ -42,15 +52,9 @@ module.exports = {
                 value: themeName
             }];
 
-            return themeService.api.activate(themeName)
-                .then((checkedTheme) => {
-                    // @NOTE: we use the model, not the API here, as we don't want to trigger permissions
-                    return models.Settings.edit(newSettings, frame.options)
-                        .then(() => checkedTheme);
-                })
-                .then((checkedTheme) => {
-                    return themeService.api.getJSON(themeName, checkedTheme);
-                });
+            const themeErrors = await themeService.api.activate(themeName);
+            await models.Settings.edit(newSettings, frame.options);
+            return themeService.api.getJSON(themeName, themeErrors);
         }
     },
 

ghost/core/core/server/data/migrations/versions/5.28/2023-01-05-15-13-add-active-theme-permissions.js

@@ -0,0 +1,12 @@
+const {addPermissionWithRoles} = require('../../utils');
+
+module.exports = addPermissionWithRoles({
+    name: 'View active theme details',
+    action: 'readActive',
+    object: 'theme'
+}, [
+    'Author',
+    'Editor',
+    'Administrator',
+    'Admin Integration'
+]);

ghost/core/core/server/data/schema/fixtures/fixtures.json

@@ -214,6 +214,11 @@
                     "action_type": "activate",
                     "object_type": "theme"
                 },
+                {
+                    "name": "View active theme details",
+                    "action_type": "readActive",
+                    "object_type": "theme"
+                },
                 {
                     "name": "Upload themes",
                     "action_type": "add",
@@ -804,7 +809,7 @@
                     "user": "all",
                     "role": "all",
                     "invite": "all",
-                    "theme": ["browse"],
+                    "theme": ["browse", "readActive"],
                     "email_preview": "all",
                     "email": "all",
                     "snippet": "all",
@@ -819,7 +824,7 @@
                     "tag": ["browse", "read", "add"],
                     "user": ["browse", "read"],
                     "role": ["browse"],
-                    "theme": ["browse"],
+                    "theme": ["browse", "readActive"],
                     "email_preview": "read",
                     "email": "read",
                     "snippet": ["browse", "read"],

ghost/core/core/server/services/themes/activate.js

@@ -21,7 +21,7 @@ module.exports.loadAndActivate = async (themeName) => {
         const loadedTheme = await themeLoader.loadOneTheme(themeName);
         // Validate
         // @NOTE: this is now the only usage of check, rather than checkSafe...
-        const checkedTheme = await validate.check(loadedTheme);
+        const checkedTheme = await validate.check(themeName, loadedTheme);
 
         if (!validate.canActivate(checkedTheme)) {
             logging.error(validate.getThemeValidationError('activeThemeHasFatalErrors', themeName, checkedTheme));
@@ -57,6 +57,6 @@ module.exports.activate = async (themeName) => {
     const checkedTheme = await validate.checkSafe(themeName, loadedTheme);
     // Activate
     await activator.activateFromAPI(themeName, loadedTheme, checkedTheme);
-    // Return the checked theme
-    return checkedTheme;
+    // Return the theme errors
+    return validate.getErrorsFromCheckedTheme(checkedTheme);
 };

ghost/core/core/server/services/themes/index.js

@@ -3,7 +3,7 @@ const themeLoader = require('./loader');
 const storage = require('./storage');
 const getJSON = require('./to-json');
 const installer = require('./installer');
-
+const validate = require('./validate');
 const settingsCache = require('../../../shared/settings-cache');
 
 module.exports = {
@@ -11,8 +11,9 @@ module.exports = {
      * Load the currently active theme
      */
     init: async () => {
-        const themeName = settingsCache.get('active_theme');
+        validate.init();
 
+        const themeName = settingsCache.get('active_theme');
         return activate.loadAndActivate(themeName);
     },
     /**
@@ -25,6 +26,7 @@ module.exports = {
     api: {
         getJSON,
         activate: activate.activate,
+        getThemeErrors: validate.getThemeErrors,
         getZip: storage.getZip,
         setFromZip: storage.setFromZip,
         installFromGithub: installer.installFromGithub,

ghost/core/core/server/services/themes/storage.js

@@ -86,10 +86,12 @@ module.exports = {
                 await activator.activateFromAPIOverride(themeName, loadedTheme, checkedTheme);
             }
 
+            const themeErrors = validate.getErrorsFromCheckedTheme(checkedTheme);
+
             // @TODO: unify the name across gscan and Ghost!
             return {
                 themeOverridden: overrideTheme,
-                theme: toJSON(themeName, checkedTheme)
+                theme: toJSON(themeName, themeErrors)
             };
         } catch (error) {
             // restore backup if we renamed an existing theme but saving failed

ghost/core/core/server/services/themes/to-json.js

@@ -13,10 +13,10 @@ const settingsCache = require('../../../shared/settings-cache');
  * @TODO: settingsCache.get('active_theme') vs. active.get().name
  *
  * @param {string} [name] - the theme to output
- * @param {object} [checkedTheme] - a theme result from gscan
+ * @param {{errors: Array, warnings: Array}} [themeErrors] - Error and warning results from checked theme (if available)
  * @return {}
  */
-module.exports = function toJSON(name, checkedTheme) {
+module.exports = function toJSON(name, themeErrors) {
     let themeResult;
     let toFilter;
 
@@ -30,12 +30,12 @@ module.exports = function toJSON(name, checkedTheme) {
 
         themeResult = packageJSON.filter(toFilter, settingsCache.get('active_theme'));
 
-        if (checkedTheme && checkedTheme.results.warning.length > 0) {
-            themeResult[0].warnings = _.cloneDeep(checkedTheme.results.warning);
+        if (themeErrors && themeErrors.warnings.length) {
+            themeResult[0].warnings = _.cloneDeep(themeErrors.warnings);
         }
 
-        if (checkedTheme && checkedTheme.results.error.length > 0) {
-            themeResult[0].errors = _.cloneDeep(checkedTheme.results.error);
+        if (themeErrors && themeErrors.errors.length) {
+            themeResult[0].errors = _.cloneDeep(themeErrors.errors);
         }
     }
 

ghost/core/core/server/services/themes/validate.js

@@ -5,20 +5,46 @@ const config = require('../../../shared/config');
 const labs = require('../../../shared/labs');
 const tpl = require('@tryghost/tpl');
 const errors = require('@tryghost/errors');
+const adapterManager = require('../adapter-manager');
+const logging = require('@tryghost/logging');
+const list = require('./list');
 
 const messages = {
     themeHasErrors: 'Theme "{theme}" is not compatible or contains errors.',
     activeThemeHasFatalErrors: 'The currently active theme "{theme}" has fatal errors.',
-    activeThemeHasErrors: 'The currently active theme "{theme}" has errors, but will still work.'
+    activeThemeHasErrors: 'The currently active theme "{theme}" has errors, but will still work.',
+    themeNotLoaded: 'Theme "{themeName}" is not loaded and cannot be checked.'
+};
+
+/**
+ * @typedef {Object} CacheStore
+ * @property {(key: string) => Promise<any>} get - get a value from the cache. Returns undefined if not found
+ * @property {(key: string, value: any) => Promise<void>} set - set a value in the cache
+ * @property {() => Promise<void>} reset - reset the cache
+ */
+
+/**
+ * The cache store for storing the result of the last theme validation
+ * @type {CacheStore}
+ */
+let gscanCacheStore;
+
+module.exports.init = () => {
+    gscanCacheStore = adapterManager.getAdapter('cache:gscan');
 };
 
 const canActivate = function canActivate(checkedTheme) {
-    // CASE: production and no fatal errors
-    // CASE: development returns fatal and none fatal errors, theme is only invalid if fatal errors
-    return !checkedTheme.results.error.length || (config.get('env') === 'development') && !checkedTheme.results.hasFatalErrors;
+    return !checkedTheme.results.hasFatalErrors;
 };
 
-const check = async function check(theme, isZip) {
+const getErrorsFromCheckedTheme = function getErrorsFromCheckedTheme(checkedTheme) {
+    return {
+        errors: checkedTheme.results.error ?? [],
+        warnings: checkedTheme.results.warning ?? []
+    };
+};
+
+const check = async function check(themeName, theme, isZip) {
     debug('Begin: Check');
     // gscan can slow down boot time if we require on boot, for now nest the require.
     const gscan = require('gscan');
@@ -41,16 +67,59 @@ const check = async function check(theme, isZip) {
     }
 
     checkedTheme = gscan.format(checkedTheme, {
-        onlyFatalErrors: config.get('env') === 'production',
+        onlyFatalErrors: false,
         checkVersion: checkedVersion
     });
 
+    // In production we don't want to show warnings
+    // Warnings are meant for developers only
+    if (config.get('env') === 'production') {
+        checkedTheme.results.warning = [];
+    }
+
+    // Cache warnings and errors
+    try {
+        await gscanCacheStore.set(themeName, getErrorsFromCheckedTheme(checkedTheme));
+    } catch (err) {
+        logging.error('Failed to cache gscan result');
+        logging.error(err);
+    }
+
     debug('End: Check');
     return checkedTheme;
 };
 
+/**
+ * Returns the last cached errors and warnings of check() if available.
+ * Otherwise runs check() on the loaded theme with that name (which will always cache the error and warning results)
+ * @returns {Promise<{errors: Array, warnings: Array}>}
+ */
+const getThemeErrors = async function getThemeErrors(themeName) {
+    try {
+        const cachedThemeErrors = await gscanCacheStore.get(themeName);
+        if (cachedThemeErrors) {
+            return cachedThemeErrors;
+        }
+    } catch (err) {
+        logging.error('Failed to get gscan result from cache');
+        logging.error(err);
+    }
+
+    const loadedTheme = list.get(themeName);
+
+    if (!loadedTheme) {
+        throw new errors.ValidationError({
+            message: tpl(messages.themeNotLoaded, {themeName: themeName}),
+            errorDetails: themeName
+        });
+    }
+
+    const result = await check(themeName, loadedTheme);
+    return getErrorsFromCheckedTheme(result);
+};
+
 const checkSafe = async function checkSafe(themeName, theme, isZip) {
-    const checkedTheme = await check(theme, isZip);
+    const checkedTheme = await check(themeName, theme, isZip);
 
     if (canActivate(checkedTheme)) {
         return checkedTheme;
@@ -83,4 +152,6 @@ const getThemeValidationError = (message, themeName, checkedTheme) => {
 module.exports.check = check;
 module.exports.checkSafe = checkSafe;
 module.exports.canActivate = canActivate;
+module.exports.getErrorsFromCheckedTheme = getErrorsFromCheckedTheme;
 module.exports.getThemeValidationError = getThemeValidationError;
+module.exports.getThemeErrors = getThemeErrors;

ghost/core/core/server/web/api/endpoints/admin/routes.js

@@ -159,6 +159,11 @@ module.exports = function apiRoutes() {
         http(api.themes.download)
     );
 
+    router.get('/themes/active',
+        mw.authAdminApi,
+        http(api.themes.readActive)
+    );
+
     router.post('/themes/upload',
         mw.authAdminApi,
         apiMw.upload.single('file'),

ghost/core/core/shared/config/defaults.json

@@ -27,7 +27,8 @@
         "cache": {
             "active": "Memory",
             "settings": {},
-            "imageSizes": {}
+            "imageSizes": {},
+            "gscan": {}
         }
     },
     "storage": {

ghost/core/test/e2e-api/admin/themes.test.js

@@ -87,6 +87,13 @@ describe('Themes API', function () {
             .expect(200);
     });
 
+    it('Can fetch active theme', async function () {
+        await ownerRequest
+            .get(localUtils.API.getApiQuery('themes/active/'))
+            .set('Origin', config.get('url'))
+            .expect(200);
+    });
+
     it('Can upload a valid theme', async function () {
         const res = await uploadTheme({themePath: path.join(__dirname, '..', '..', 'utils', 'fixtures', 'themes', 'valid.zip')});
         const jsonResponse = res.body;
@@ -264,6 +271,14 @@ describe('Themes API', function () {
         localUtils.API.checkResponse(testTheme2, 'theme', ['warnings', 'templates']);
         testTheme2.active.should.be.true();
         testTheme2.warnings.should.be.an.Array();
+
+        // Result should be the same
+        const activeThemeResult = await ownerRequest
+            .get(localUtils.API.getApiQuery('themes/active/'))
+            .set('Origin', config.get('url'))
+            .expect(200);
+
+        res2.body.should.eql(activeThemeResult.body);
     });
 
     it('Can download and install a theme from GitHub', async function () {

ghost/core/test/integration/migrations/migration.test.js

@@ -45,7 +45,7 @@ describe('Database Migration (special functions)', function () {
             const permissions = this.obj;
 
             // If you have to change this number, please add the relevant `havePermission` checks below
-            permissions.length.should.eql(108);
+            permissions.length.should.eql(109);
 
             permissions.should.havePermission('Export database', ['Administrator', 'DB Backup Integration']);
             permissions.should.havePermission('Import database', ['Administrator', 'DB Backup Integration']);
@@ -80,6 +80,7 @@ describe('Database Migration (special functions)', function () {
             permissions.should.havePermission('Browse themes', ['Administrator', 'Editor', 'Author', 'Contributor', 'Admin Integration']);
             permissions.should.havePermission('Edit themes', ['Administrator', 'Admin Integration']);
             permissions.should.havePermission('Activate themes', ['Administrator', 'Admin Integration']);
+            permissions.should.havePermission('View active theme details', ['Administrator', 'Editor', 'Author', 'Admin Integration']);
             permissions.should.havePermission('Upload themes', ['Administrator', 'Admin Integration']);
             permissions.should.havePermission('Download themes', ['Administrator', 'Admin Integration']);
             permissions.should.havePermission('Delete themes', ['Administrator', 'Admin Integration']);

ghost/core/test/unit/server/data/schema/integrity.test.js

@@ -36,7 +36,7 @@ const validateRouteSettings = require('../../../../../core/server/services/route
 describe('DB version integrity', function () {
     // Only these variables should need updating
     const currentSchemaHash = 'a3df9e11b3db1c8afdfb87c7a206b53b';
-    const currentFixturesHash = 'dcb7ba7c66b4b98d6c26a722985e756a';
+    const currentFixturesHash = 'f0ccdb0c7eccbc3311e38b5d145ed1db';
     const currentSettingsHash = '9acce72858e75420b831297718595bbd';
     const currentRoutesHash = '3d180d52c663d173a6be791ef411ed01';
 

ghost/core/test/unit/server/services/themes/validate.test.js

@@ -1,10 +1,11 @@
 const should = require('should');
 const sinon = require('sinon');
 const _ = require('lodash');
-
 const validate = require('../../../../../core/server/services/themes/validate');
-
+const list = require('../../../../../core/server/services/themes/list');
 const gscan = require('gscan');
+const assert = require('assert');
+const adapterManager = require('../../../../../core/server/services/adapter-manager');
 
 describe('Themes', function () {
     let checkZipStub;
@@ -32,7 +33,7 @@ describe('Themes', function () {
             checkZipStub.resolves({});
             formatStub.returns({results: {error: []}});
 
-            return validate.check(testTheme, true)
+            return validate.check(testTheme.name, testTheme, true)
                 .then((checkedTheme) => {
                     checkZipStub.calledOnce.should.be.true();
                     checkZipStub.calledWith(testTheme).should.be.true();
@@ -48,7 +49,7 @@ describe('Themes', function () {
             checkStub.resolves({});
             formatStub.returns({results: {error: []}});
 
-            return validate.check(testTheme, false)
+            return validate.check(testTheme.name, testTheme, false)
                 .then((checkedTheme) => {
                     checkZipStub.callCount.should.be.equal(0);
                     checkStub.calledOnce.should.be.true();
@@ -73,11 +74,12 @@ describe('Themes', function () {
                             failures: [{}],
                             code: 'GS001-DEPR-CON-AC'
                         }
-                    ]
+                    ],
+                    hasFatalErrors: true
                 }
             });
 
-            return validate.check(testTheme, true)
+            return validate.check(testTheme.name, testTheme, true)
                 .then((checkedTheme) => {
                     checkZipStub.calledOnce.should.be.true();
                     checkZipStub.calledWith(testTheme).should.be.true();
@@ -101,11 +103,12 @@ describe('Themes', function () {
                             failures: [{}],
                             code: 'GS001-DEPR-CON-AC'
                         }
-                    ]
+                    ],
+                    hasFatalErrors: true
                 }
             });
 
-            return validate.check(testTheme, false)
+            return validate.check(testTheme.name, testTheme, false)
                 .then((checkedTheme) => {
                     checkStub.calledOnce.should.be.true();
                     checkStub.calledWith(testTheme.path).should.be.true();
@@ -120,7 +123,7 @@ describe('Themes', function () {
             checkZipStub.rejects(new Error('invalid zip file'));
             formatStub.returns({results: {error: []}});
 
-            return validate.check(testTheme, true)
+            return validate.check(testTheme.name, testTheme, true)
                 .then((checkedTheme) => {
                     checkedTheme.should.not.exist();
                 }).catch((error) => {
@@ -133,4 +136,56 @@ describe('Themes', function () {
                 });
         });
     });
+
+    describe('getThemeErrors', function () {
+        const testTheme = {
+            name: 'supertheme',
+            version: '1.0.0',
+            path: '/path/to/theme'
+        };
+
+        before(function () {
+            list.init();
+            list.set(testTheme.name, testTheme);
+            validate.init();
+        });
+
+        it('Does an innitial check if not cached yet', async function () {
+            checkStub.resolves({});
+            formatStub.returns({results: {error: [{hello: 'world'}]}});
+
+            const checkedTheme = await validate.getThemeErrors(testTheme.name);
+            sinon.assert.calledOnce(checkStub);
+            sinon.assert.calledOnce(formatStub);
+            assert.deepEqual(checkedTheme, {errors: [{hello: 'world'}], warnings: []});
+        });
+
+        it('Reuses same result if called again', async function () {
+            const checkedTheme = await validate.getThemeErrors(testTheme.name);
+            sinon.assert.notCalled(checkStub);
+            sinon.assert.notCalled(formatStub);
+            assert.deepEqual(checkedTheme, {errors: [{hello: 'world'}], warnings: []});
+        });
+
+        it('Throws for invalid theme names', async function () {
+            await assert.rejects(validate.getThemeErrors('invalid-theme-name'), /Theme "invalid-theme-name" is not loaded and cannot be checked/);
+        });
+
+        it('Silently fails when cache adapter throws', async function () {
+            sinon.stub(adapterManager, 'getAdapter').returns({
+                get: () => {
+                    throw new Error('test');
+                }
+            });
+            validate.init();
+
+            checkStub.resolves({});
+            formatStub.returns({results: {error: [{hello: 'world'}]}});
+
+            const checkedTheme = await validate.getThemeErrors(testTheme.name);
+            sinon.assert.calledOnce(checkStub);
+            sinon.assert.calledOnce(formatStub);
+            assert.deepEqual(checkedTheme, {errors: [{hello: 'world'}], warnings: []});
+        });
+    });
 });

ghost/core/test/utils/fixtures/fixtures.json

@@ -219,6 +219,11 @@
                     "action_type": "activate",
                     "object_type": "theme"
                 },
+                {
+                    "name": "View active theme details",
+                    "action_type": "readActive",
+                    "object_type": "theme"
+                },
                 {
                     "name": "Upload themes",
                     "action_type": "add",
@@ -980,7 +985,7 @@
                     "user": "all",
                     "role": "all",
                     "invite": "all",
-                    "theme": ["browse"],
+                    "theme": ["browse", "readActive"],
                     "email_preview": "all",
                     "email": "all",
                     "snippet": "all",
@@ -995,7 +1000,7 @@
                     "tag": ["browse", "read", "add"],
                     "user": ["browse", "read"],
                     "role": ["browse"],
-                    "theme": ["browse"],
+                    "theme": ["browse", "readActive"],
                     "email_preview": "read",
                     "email": "read",
                     "snippet": ["browse", "read"],