Correct description of how service name appears

This has changed since we made prefixing text messages its own setting.

app/templates/views/service-settings/name.html

@@ -10,13 +10,16 @@
 
   <h1 class="heading-large">Change your service name</h1>
 
-
   <div class="form-group">
-    <p>Users will see your service name:</p>
+    {% if current_service.prefix_sms %}
-    <ul class="list-bullet">
+      <p>Users will see your service name:</p>
-      <li>at the start of every text message, eg ‘Vehicle tax: we received your payment, thank you’</li>
+      <ul class="list-bullet">
-      <li>as your email sender name</li>
+        <li>at the start of every text message, eg ‘{{ current_service.name }}: This is an example message’</li>
-    </ul>
+        <li>as your email sender name</li>
+      </ul>
+    {% else %}
+      <p>Users will see your service name as your email sender name.</p>
+    {% endif %}
   </div>
 
   <form method="post">

tests/app/main/views/test_service_settings.py

@@ -236,16 +236,27 @@ def test_escapes_letter_contact_block(
 
 
 def test_should_show_service_name(
-        logged_in_client,
+    client_request,
-        service_one,
 ):
-    response = logged_in_client.get(url_for(
+    page = client_request.get('main.service_name_change', service_id=SERVICE_ONE_ID)
-        'main.service_name_change', service_id=service_one['id']))
-    assert response.status_code == 200
-    page = BeautifulSoup(response.data.decode('utf-8'), 'html.parser')
     assert page.find('h1').text == 'Change your service name'
     assert page.find('input', attrs={"type": "text"})['value'] == 'service one'
-    app.service_api_client.get_service.assert_called_with(service_one['id'])
+    assert page.select_one('main p').text == 'Users will see your service name:'
+    assert normalize_spaces(page.select_one('main ul').text) == (
+        'at the start of every text message, eg ‘service one: This is an example message’ '
+        'as your email sender name'
+    )
+    app.service_api_client.get_service.assert_called_with(SERVICE_ONE_ID)
+
+
+def test_should_show_service_name_with_no_prefixing(
+    client_request,
+    service_one,
+):
+    service_one['prefix_sms'] = False
+    page = client_request.get('main.service_name_change', service_id=SERVICE_ONE_ID)
+    assert page.find('h1').text == 'Change your service name'
+    assert page.select_one('main p').text == 'Users will see your service name as your email sender name.'
 
 
 def test_should_redirect_after_change_service_name(