Simplify network choice to optional radio buttons

Previously this field had to mimic the final hyphenated string of
the broadcast account type, even though it was only used to select
one of its components. The new, shorter choices make it easier to
simplify the test for the POST request.

I've also deleted a number of test cases for pre-selected radios.
This functionality isn't critical, so we don't need to exhaustively
test every single possible combination of values.

app/main/forms.py

@@ -881,6 +881,13 @@ class GovukRadiosField(RadioField):
         return govuk_radios_field_widget(self, field, param_extensions=param_extensions, **kwargs)
 
 
+class OptionalGovukRadiosField(GovukRadiosField):
+    def pre_validate(self, form):
+        if self.data is None:
+            return
+        super().pre_validate(form)
+
+
 class OnOffField(GovukRadiosField):
 
     def __init__(self, label, choices=None, *args, **kwargs):
@@ -2384,13 +2391,6 @@ class ServiceBroadcastAccountTypeField(GovukRadiosField):
             self.provider_restriction = split_values[2]
 
 
-class OptionalServiceBroadcastAccountTypeField(ServiceBroadcastAccountTypeField):
-    def pre_validate(self, form):
-        if self.data is None:
-            return
-        super().pre_validate(form)
-
-
 class ServiceBroadcastChannelForm(StripWhitespaceForm):
     channel = ServiceBroadcastAccountTypeField(
         'Emergency alerts settings',
@@ -2409,13 +2409,6 @@ class ServiceBroadcastNetworkForm(StripWhitespaceForm):
         super().__init__(*args, **kwargs)
         self.broadcast_channel = broadcast_channel
 
-        self.network.choices = [
-            (f'live-{broadcast_channel}-ee', 'EE'),
-            (f'live-{broadcast_channel}-o2', 'O2'),
-            (f'live-{broadcast_channel}-vodafone', 'Vodafone'),
-            (f'live-{broadcast_channel}-three', 'Three'),
-        ]
-
     all_networks = OnOffField(
         'Choose a mobile network',
         choices=(
@@ -2423,9 +2416,15 @@ class ServiceBroadcastNetworkForm(StripWhitespaceForm):
             (False, 'A single network')
         ),
     )
-    network = OptionalServiceBroadcastAccountTypeField(
+    network = OptionalGovukRadiosField(
         'Choose a mobile network',
         thing='a mobile network',
+        choices=(
+            ('ee', 'EE'),
+            ('o2', 'O2'),
+            ('vodafone', 'Vodafone'),
+            ('three', 'Three'),
+        ),
     )
 
     @property
@@ -2433,7 +2432,7 @@ class ServiceBroadcastNetworkForm(StripWhitespaceForm):
         if self.all_networks.data:
             provider = 'all'
         else:
-            provider = self.network.provider_restriction
+            provider = self.network.data
 
         return f'live-{self.broadcast_channel}-{provider}'
 

app/main/views/service_settings.py

@@ -355,21 +355,11 @@ def service_set_broadcast_network(service_id, broadcast_channel):
     if current_service.broadcast_channel == broadcast_channel:
         provider = current_service.allowed_broadcast_provider
 
-        if provider == 'all':
-            form = ServiceBroadcastNetworkForm(
-                broadcast_channel=broadcast_channel,
-                all_networks=True,
-            )
-        else:
-            form = ServiceBroadcastNetworkForm(
-                broadcast_channel=broadcast_channel,
-                all_networks=False,
-                network=(
-                    current_service.live,
-                    current_service.broadcast_channel,
-                    provider,
-                )
-            )
+        form = ServiceBroadcastNetworkForm(
+            broadcast_channel=broadcast_channel,
+            all_networks=provider == 'all',
+            network=provider if provider != 'all' else None,
+        )
     else:
         form = ServiceBroadcastNetworkForm(
             broadcast_channel=broadcast_channel