datetime: Add functional test for setting time zone

Reviewed-by: James Valleroy <jvalleroy@mailbox.org>

functional_tests/features/date_and_time.feature

@@ -31,3 +31,7 @@ Scenario: Disable network time application
   Given the network time application is enabled
   When I disable the network time application
   Then the network time service should not be running
+
+Scenario: Set timezone
+  When I set the time zone to Africa/Abidjan
+  Then the time zone should be Africa/Abidjan

functional_tests/step_definitions/application.py

@@ -47,6 +47,16 @@ def ntp_is_disabled(browser):
     application.disable(browser, 'ntp')
 
 
+@when(parsers.parse('I set the time zone to {time_zone:S}'))
+def time_zone_set(browser, time_zone):
+    application.time_zone_set(browser, time_zone)
+
+
+@then(parsers.parse('the time zone should be {time_zone:S}'))
+def time_zone_assert(browser, time_zone):
+    assert time_zone == application.time_zone_get(browser)
+
+
 @given(parsers.parse('the service discovery application is enabled'))
 def avahi_is_enabled(browser):
     application.enable(browser, 'avahi')

functional_tests/support/application.py

@@ -322,3 +322,16 @@ def ikiwiki_wiki_exists(browser):
     browser.find_link_by_href('/plinth/apps/ikiwiki/manage/').first.click()
     wiki = browser.find_link_by_href('/ikiwiki/wiki')
     return bool(wiki)
+
+
+def time_zone_set(browser, time_zone):
+    """Set the system time zone."""
+    interface.nav_to_module(browser, 'datetime')
+    browser.select('time_zone', time_zone)
+    interface.submit(browser, form_class='form-configuration')
+
+
+def time_zone_get(browser):
+    """Set the system time zone."""
+    interface.nav_to_module(browser, 'datetime')
+    return browser.find_by_name('time_zone').first.value