[FIX] web: always use browser timezone

With the new views, we stopped using the browser timezone to
display the dates in Odoo, and we used the timezone defined on
the User profile instead. When loading the webclient, the
timezone offset was put into the session and used to display all
dates. This wasn't a good idea.

The given offset was computed for the current time, meaning that
it may be incorrect for specific dates (e.g. with the daylight
saving, the UTC offset of today is not the same as 6 months ago).
Moreover (but less likely), as the offset was stored in the
session, it wasn't recalculated afterwards. So if the offset
actually changed during the session (e.g. from or to daylight
saving time), the displayed dates were incorrect until the user
reloaded the page.

With this rev., we don't retrieve the offset from the server
anymore and we use the browser timezone again (like before the new
views). However, we keep the computation of the offset (on the fly)
in the session, so that it can be mocked in the test environment.

1 files changed, 26 insertions, 0 deletions

diff --git a/addons/web/static/tests/fields/field_utils_tests.js b/addons/web/static/tests/fields/field_utils_tests.js
index 922c9f3a79c..a0284798553 100644
--- a/addons/web/static/tests/fields/field_utils_tests.js
+++ b/addons/web/static/tests/fields/field_utils_tests.js
@@ -4,6 +4,7 @@ odoo.define('web.field_utils_tests', function (require) {
 var core = require('web.core');
 var session = require('web.session');
 var fieldUtils = require('web.field_utils');
+var testUtils = require('web.test_utils');
 
 QUnit.module('fields', {}, function () {
 
@@ -63,6 +64,31 @@ QUnit.test("format_datetime", function (assert) {
     assert.strictEqual(str, moment(date).format("MM/DD/YYYY HH:mm:ss"));
 });
 
+QUnit.test("format_datetime (with different timezone offset)", function (assert) {
+    assert.expect(2);
+
+    // mock the date format to avoid issues due to localisation
+    var dateFormat = core._t.database.parameters.date_format;
+    core._t.database.parameters.date_format = '%m/%d/%Y';
+    session.getTZOffset = function (date) {
+        // simulate daylight saving time
+        var startDate = new Date(2017, 2, 26);
+        var endDate   = new Date(2017, 9, 29);
+        if (startDate < date && date < endDate) {
+            return 120; // UTC+2
+        } else {
+            return 60; // UTC+1
+        }
+    };
+
+    var str = fieldUtils.format.datetime(moment.utc('2017-01-01T10:00:00Z'));
+    assert.strictEqual(str, '01/01/2017 11:00:00');
+    str = fieldUtils.format.datetime(moment.utc('2017-06-01T10:00:00Z'));
+    assert.strictEqual(str, '06/01/2017 12:00:00');
+
+    core._t.database.parameters.date_format = dateFormat;
+});
+
 QUnit.test("format_many2one", function (assert) {
     assert.expect(2);