Only show back to service link if you have service

It doesn’t make sense to show the back to service link if, for example,
you are in the onboarding flow and haven’t created a service yet.

app/templates/withoutnav_template.html

@@ -2,9 +2,9 @@
 
 {% block fullwidth_content %}
   <div id="content">
-    {% if current_user.is_authenticated %}
+    {% if current_service %}
     <div class="navigation-service">
-      <a href="{{ url_for('main.show_all_services_or_dashboard') }}">Back to service</a>
+      <a href="{{ url_for('main.show_all_services_or_dashboard') }}">Back to {{ current_service.name }}</a>
     </div>
     {% endif %}
     <main role="main">

tests/app/main/views/test_choose_services.py

@@ -1,4 +1,5 @@
 from flask import url_for
+from bs4 import BeautifulSoup
 
 
 def test_should_show_choose_services_page(
@@ -83,3 +84,29 @@ def test_should_redirect_if_not_logged_in(
     response = logged_in_client.get(url_for('main.show_all_services_or_dashboard'))
     assert response.status_code == 302
     assert url_for('main.index', _external=True) in response.location
+
+
+def test_should_show_back_to_service_link(
+    logged_in_client
+):
+    response = logged_in_client.get(url_for('main.choose_service'))
+
+    assert response.status_code == 200
+    page = BeautifulSoup(response.data.decode('utf-8'), 'html.parser')
+    assert page.select('.navigation-service a')[0]['href'] == (
+        url_for('main.show_all_services_or_dashboard')
+    )
+
+
+def test_should_not_show_back_to_service_link_if_no_service_in_session(
+    client,
+    api_user_active,
+    mock_get_user,
+    mock_get_services_with_no_services,
+):
+    client.login(api_user_active)
+    response = client.get(url_for('main.choose_service'))
+
+    assert response.status_code == 200
+    page = BeautifulSoup(response.data.decode('utf-8'), 'html.parser')
+    assert len(page.select('.navigation-service a')) == 0