Fix `appBackgroundColor` theme property handling

Fix an incorrect call to `applyTheme` which passed an invalid theme
property name. This is a regression from when this component was converted
from AngularJS to Preact in 7bbb8a60.

Also improve the type definitions of `applyTheme` and add a test to help catch
such mistakes in future.

Fixes #2439

src/sidebar/components/annotation-publish-control.js

@@ -15,6 +15,7 @@ import SvgIcon from '../../shared/components/svg-icon';
 /**
  * @typedef {import('../../types/api').Annotation} Annotation
  * @typedef {import('../../types/config').MergedConfig} MergedConfig
+ * @typedef {import('../util/theme').ThemeProperty} ThemeProperty
  */
 
 /**
@@ -56,6 +57,8 @@ function AnnotationPublishControl({
   const isPrivate = draft ? draft.isPrivate : !isShared(annotation.permissions);
 
   const publishDestination = isPrivate ? 'Only Me' : group.name;
+
+  /** @type {ThemeProperty[]} */
   const themeProps = ['ctaTextColor', 'ctaBackgroundColor'];
 
   // Revert changes to this annotation

src/sidebar/components/hypothesis-app.js

@@ -77,7 +77,7 @@ function HypothesisApp({
   }, [hasFetchedProfile, profile]);
 
   const backgroundStyle = useMemo(
-    () => applyTheme(['backgroundColor'], settings),
+    () => applyTheme(['appBackgroundColor'], settings),
     [settings]
   );
 

src/sidebar/components/test/hypothesis-app-test.js

@@ -7,6 +7,7 @@ import mockImportedComponents from '../../../test-util/mock-imported-components'
 import HypothesisApp, { $imports } from '../hypothesis-app';
 
 describe('HypothesisApp', () => {
+  let fakeApplyTheme;
   let fakeUserAgent = null;
   let fakeStore = null;
   let fakeAuth = null;
@@ -33,6 +34,7 @@ describe('HypothesisApp', () => {
   };
 
   beforeEach(() => {
+    fakeApplyTheme = sinon.stub().returns({});
     fakeServiceConfig = sinon.stub();
     fakeShouldAutoDisplayTutorial = sinon.stub().returns(false);
 
@@ -89,6 +91,7 @@ describe('HypothesisApp', () => {
       '../util/session': {
         shouldAutoDisplayTutorial: fakeShouldAutoDisplayTutorial,
       },
+      '../util/theme': { applyTheme: fakeApplyTheme },
     });
   });
 
@@ -449,4 +452,15 @@ describe('HypothesisApp', () => {
       });
     });
   });
+
+  it('applies theme config', () => {
+    const style = { backgroundColor: 'red' };
+    fakeApplyTheme.returns({ backgroundColor: 'red' });
+
+    const wrapper = createComponent();
+    const background = wrapper.find('.hypothesis-app');
+
+    assert.calledWith(fakeApplyTheme, ['appBackgroundColor'], fakeSettings);
+    assert.deepEqual(background.prop('style'), style);
+  });
 });

src/sidebar/util/theme.js

-/**
- * @const {Object} All supported options for theming and their corresponding
- *                 CSS property names (JS-style)
- */
 const supportedThemeProperties = {
   accentColor: 'color',
   appBackgroundColor: 'backgroundColor',
@@ -11,6 +7,19 @@ const supportedThemeProperties = {
   annotationFontFamily: 'fontFamily',
 };
 
+/**
+ * Name of a theme element which can be configured.
+ *
+ * @typedef {keyof supportedThemeProperties} ThemeProperty
+ */
+
+/**
+ * Subset of the config from the host page which includes theme configuration.
+ *
+ * @typedef Settings
+ * @prop {Object.<ThemeProperty,string>} [branding]
+ */
+
 /**
  * Return a React `style` object suitable for use as the value of the `style`
  * attr in a React element, with styling rules for the requested set of
@@ -27,12 +36,11 @@ const supportedThemeProperties = {
  *
  * See https://reactjs.org/docs/dom-elements.html#style
  *
- * @param {String[]} themeProperties    Which of the supported theme properties
- *                                      should have applied rules in the `style`
+ * @param {ThemeProperty[]} themeProperties -
+ *   Which of the supported theme properties should have applied rules in the `style`
  *   object
- * @param {Object} settings             A settings object, in which any `branding`
- *                                      property values are set
- * @return {Object}                     An React-style style object
+ * @param {Settings} settings
+ * @return {Object.<string,string>} - Object that can be passed as the `style` prop
  *
  * @example
  * let themeProperties = ['accentColor', 'ctaTextColor', 'foo'];
@@ -46,6 +54,7 @@ const supportedThemeProperties = {
  * applyTheme(themeProperties, settings); // -> { color: '#ffc '}
  */
 export function applyTheme(themeProperties, settings) {
+  /** @type {Object.<string,string>} */
   const style = {};
   if (!settings.branding) {
     return style;