create favicon overlay on the client

the initial reason for this change was that graphicsmagick does not
support writing to ico files. this fact lead to a chain of changes:

1. use png instead of ico (browser support is good enough)
2. render the overlays on the client using the canvas API. this way we
   only need to store the original favion and generate the overlay versions
   dynamically.
   this change also enables (next step) to simplify the handling of the
   stock favicons as well, as we don't need to generate all the versions
   upfront.

2 files changed, 37 insertions, 4 deletions

diff --git a/spec/javascripts/lib/utils/common_utils_spec.js b/spec/javascripts/lib/utils/common_utils_spec.js
index 64d13275a59..2d7cc3443cf 100644
--- a/spec/javascripts/lib/utils/common_utils_spec.js
+++ b/spec/javascripts/lib/utils/common_utils_spec.js
@@ -2,6 +2,7 @@
 import axios from '~/lib/utils/axios_utils';
 import * as commonUtils from '~/lib/utils/common_utils';
 import MockAdapter from 'axios-mock-adapter';
+import { faviconDataUrl, overlayDataUrl, faviconWithOverlayDataUrl } from './mock_data';
 
 describe('common_utils', () => {
   describe('parseUrl', () => {
@@ -430,6 +431,35 @@ describe('common_utils', () => {
     });
   });
 
+  describe('createOverlayIcon', () => {
+    it('should return the favicon with the overlay', (done) => {
+      commonUtils.createOverlayIcon(faviconDataUrl, overlayDataUrl).then((url) => {
+        expect(url).toEqual(faviconWithOverlayDataUrl);
+        done();
+      });
+    });
+  });
+
+  describe('setFaviconOverlay', () => {
+    beforeEach(() => {
+      const favicon = document.createElement('link');
+      favicon.setAttribute('id', 'favicon');
+      favicon.setAttribute('data-original-href', faviconDataUrl);
+      document.body.appendChild(favicon);
+    });
+
+    afterEach(() => {
+      document.body.removeChild(document.getElementById('favicon'));
+    });
+
+    it('should set page favicon to provided favicon overlay', (done) => {
+      commonUtils.setFaviconOverlay(overlayDataUrl).then(() => {
+        expect(document.getElementById('favicon').getAttribute('href')).toEqual(faviconWithOverlayDataUrl);
+        done();
+      });
+    });
+  });
+
   describe('setCiStatusFavicon', () => {
     const BUILD_URL = `${gl.TEST_HOST}/frontend-fixtures/builds-project/-/jobs/1/status.json`;
     let mock;
@@ -463,16 +493,14 @@ describe('common_utils', () => {
     });
 
     it('should set page favicon to CI status favicon based on provided status', (done) => {
-      const FAVICON_PATH = '//icon_status_success';
-
       mock.onGet(BUILD_URL).reply(200, {
-        favicon: FAVICON_PATH,
+        favicon: overlayDataUrl,
       });
 
       commonUtils.setCiStatusFavicon(BUILD_URL)
         .then(() => {
           const favicon = document.getElementById('favicon');
-          expect(favicon.getAttribute('href')).toEqual(FAVICON_PATH);
+          expect(favicon.getAttribute('href')).toEqual(faviconWithOverlayDataUrl);
           done();
         })
         .catch(done.fail);
diff --git a/spec/javascripts/lib/utils/mock_data.js b/spec/javascripts/lib/utils/mock_data.js
new file mode 100644
index 00000000000..fd0d62b751f
--- /dev/null
+++ b/spec/javascripts/lib/utils/mock_data.js
@@ -0,0 +1,5 @@
+export const faviconDataUrl = 'data:image/png;base64,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';
+
+export const overlayDataUrl = 'data:image/png;base64,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';
+
+export const faviconWithOverlayDataUrl = 'data:image/png;base64,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';