Localize time units on activity heatmap (#21570)

Previously, the months and days were hardcoded into English

* Closes #15541

## Screenshots
### English

![image](https://user-images.githubusercontent.com/20454870/197410352-1b28a637-ce19-41ae-b4e5-27955555b082.png)

### German

![image](https://user-images.githubusercontent.com/20454870/197410455-f243ca84-807f-476e-b8ed-c24e827bfc2d.png)

### Spanish

![image](https://user-images.githubusercontent.com/20454870/197410366-55202ca5-08f9-4152-8f9d-d5eeebd532ef.png)

### Italian

![image](https://user-images.githubusercontent.com/20454870/197410385-75f754dd-e845-4444-8a04-472a8f45b617.png)

### Portuguese
This one has a bit of overflow

![image](https://user-images.githubusercontent.com/20454870/197410414-b91f962e-77e9-4cc7-990b-01c0fc0cbd0b.png)

Signed-off-by: Yarden Shoham <hrsi88@gmail.com>
Co-authored-by: Gusted <williamzijl7@hotmail.com>
Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: techknowlogick <techknowlogick@gitea.io>

1 files changed, 23 insertions, 1 deletions

diff --git a/web_src/js/utils.test.js b/web_src/js/utils.test.js
index 7bf5bb7eb6..0567a5c64a 100644
--- a/web_src/js/utils.test.js
+++ b/web_src/js/utils.test.js
@@ -1,7 +1,7 @@
 import {expect, test} from 'vitest';
 import {
   basename, extname, isObject, uniq, stripTags, joinPaths, parseIssueHref,
-  prettyNumber, parseUrl,
+  prettyNumber, parseUrl, translateMonth, translateDay
 } from './utils.js';
 
 test('basename', () => {
@@ -109,3 +109,25 @@ test('parseUrl', () => {
   expect(parseUrl('https://localhost/path?search').search).toEqual('?search');
   expect(parseUrl('https://localhost/path?search#hash').hash).toEqual('#hash');
 });
+
+test('translateMonth', () => {
+  const originalLang = document.documentElement.lang;
+  document.documentElement.lang = 'en-US';
+  expect(translateMonth(0)).toEqual('Jan');
+  expect(translateMonth(4)).toEqual('May');
+  document.documentElement.lang = 'es-ES';
+  expect(translateMonth(5)).toEqual('jun');
+  expect(translateMonth(6)).toEqual('jul');
+  document.documentElement.lang = originalLang;
+});
+
+test('translateDay', () => {
+  const originalLang = document.documentElement.lang;
+  document.documentElement.lang = 'fr-FR';
+  expect(translateDay(1)).toEqual('lun.');
+  expect(translateDay(5)).toEqual('ven.');
+  document.documentElement.lang = 'pl-PL';
+  expect(translateDay(1)).toEqual('pon.');
+  expect(translateDay(5)).toEqual('pt.');
+  document.documentElement.lang = originalLang;
+});