Require IDs to be UUIDs in URLS

We mostly rely on the API returning a 404 to generate 404s for trying
to get things with non-UUID IDs. This is fine, except our tests often
mock these API calls. So it could look like everything is working fine,
except the thing your passing in might never be a valid UUID, and thus
would 404 in a non-test environment.

So this commit:
1. uses the `uuid` URL converter everywhere there’s something that looks
   like an ID in a URL parameter
2.  adds a test which automates checking for 1.

app/main/views/templates.py

@@ -47,7 +47,7 @@ form_objects = {
 }
 
 
-@main.route("/services/<service_id>/templates/<uuid:template_id>")
+@main.route("/services/<uuid:service_id>/templates/<uuid:template_id>")
 @user_has_permissions()
 def view_template(service_id, template_id):
     template = current_service.get_template(template_id)
@@ -84,7 +84,7 @@ def view_template(service_id, template_id):
     )
 
 
-@main.route("/services/<service_id>/start-tour/<uuid:template_id>")
+@main.route("/services/<uuid:service_id>/start-tour/<uuid:template_id>")
 @user_has_permissions('view_activity')
 def start_tour(service_id, template_id):
 
@@ -104,10 +104,10 @@ def start_tour(service_id, template_id):
     )
 
 
-@main.route("/services/<service_id>/templates", methods=['GET', 'POST'])
-@main.route("/services/<service_id>/templates/folders/<template_folder_id>", methods=['GET', 'POST'])
-@main.route("/services/<service_id>/templates/<template_type>", methods=['GET', 'POST'])
-@main.route("/services/<service_id>/templates/<template_type>/folders/<template_folder_id>", methods=['GET', 'POST'])
+@main.route("/services/<uuid:service_id>/templates", methods=['GET', 'POST'])
+@main.route("/services/<uuid:service_id>/templates/folders/<uuid:template_folder_id>", methods=['GET', 'POST'])
+@main.route("/services/<uuid:service_id>/templates/<template_type>", methods=['GET', 'POST'])
+@main.route("/services/<uuid:service_id>/templates/<template_type>/folders/<uuid:template_folder_id>", methods=['GET', 'POST'])
 @user_has_permissions()
 def choose_template(service_id, template_type='all', template_folder_id=None):
     template_folder = current_service.get_template_folder(template_folder_id)
@@ -215,7 +215,7 @@ def get_template_nav_items(template_folder_id):
     ]
 
 
-@main.route("/services/<service_id>/templates/<template_id>.<filetype>")
+@main.route("/services/<uuid:service_id>/templates/<uuid:template_id>.<filetype>")
 @user_has_permissions()
 def view_letter_template_preview(service_id, template_id, filetype):
     if filetype not in ('pdf', 'png'):
@@ -267,7 +267,7 @@ def _view_template_version(service_id, template_id, version, letters_as_pdf=Fals
     ))
 
 
-@main.route("/services/<service_id>/templates/<template_id>/version/<int:version>")
+@main.route("/services/<uuid:service_id>/templates/<uuid:template_id>/version/<int:version>")
 @user_has_permissions()
 def view_template_version(service_id, template_id, version):
     return render_template(
@@ -276,7 +276,7 @@ def view_template_version(service_id, template_id, version):
     )
 
 
-@main.route("/services/<service_id>/templates/<template_id>/version/<int:version>.<filetype>")
+@main.route("/services/<uuid:service_id>/templates/<uuid:template_id>/version/<int:version>.<filetype>")
 @user_has_permissions()
 def view_template_version_preview(service_id, template_id, version, filetype):
     db_template = current_service.get_template(template_id, version=version)
@@ -313,7 +313,6 @@ def _add_template_by_type(template_type, template_folder_id):
             service_id=current_service.id,
             notification_type=template_type,
             return_to='add_new_template',
-            template_id='0'
         ))
     else:
         return redirect(url_for(
@@ -324,10 +323,10 @@ def _add_template_by_type(template_type, template_folder_id):
         ))
 
 
-@main.route("/services/<service_id>/templates/copy")
-@main.route("/services/<service_id>/templates/copy/from-folder/<uuid:from_folder>")
-@main.route("/services/<service_id>/templates/copy/from-service/<uuid:from_service>")
-@main.route("/services/<service_id>/templates/copy/from-service/<uuid:from_service>/from-folder/<uuid:from_folder>")
+@main.route("/services/<uuid:service_id>/templates/copy")
+@main.route("/services/<uuid:service_id>/templates/copy/from-folder/<uuid:from_folder>")
+@main.route("/services/<uuid:service_id>/templates/copy/from-service/<uuid:from_service>")
+@main.route("/services/<uuid:service_id>/templates/copy/from-service/<uuid:from_service>/from-folder/<uuid:from_folder>")
 @user_has_permissions('manage_templates')
 def choose_template_to_copy(
     service_id,
@@ -362,7 +361,7 @@ def choose_template_to_copy(
         )
 
 
-@main.route("/services/<service_id>/templates/copy/<uuid:template_id>", methods=['GET', 'POST'])
+@main.route("/services/<uuid:service_id>/templates/copy/<uuid:template_id>", methods=['GET', 'POST'])
 @user_has_permissions('manage_templates')
 def copy_template(service_id, template_id):
     from_service = request.args.get('from_service')
@@ -405,9 +404,16 @@ def _get_template_copy_name(template, existing_templates):
     return '{} (copy)'.format(template['name'])
 
 
-@main.route("/services/<service_id>/templates/action-blocked/<notification_type>/<return_to>/<template_id>")
+@main.route((
+    '/services/<uuid:service_id>/templates/action-blocked/'
+    '<notification_type>'
+))
+@main.route((
+    '/services/<uuid:service_id>/templates/action-blocked/'
+    '<notification_type>/<return_to>/<uuid:template_id>'
+))
 @user_has_permissions('manage_templates')
-def action_blocked(service_id, notification_type, return_to, template_id):
+def action_blocked(service_id, notification_type, return_to='add_new_template', template_id=None):
     if notification_type == 'sms':
         notification_type = 'text messages'
     elif notification_type == 'email':
@@ -418,11 +424,11 @@ def action_blocked(service_id, notification_type, return_to, template_id):
         service_id=service_id,
         notification_type=notification_type,
         return_to=return_to,
-        template_id=template_id
+        template_id=template_id,
     )
 
 
-@main.route("/services/<service_id>/templates/folders/<template_folder_id>/manage", methods=['GET', 'POST'])
+@main.route("/services/<uuid:service_id>/templates/folders/<uuid:template_folder_id>/manage", methods=['GET', 'POST'])
 @user_has_permissions('manage_templates')
 def manage_template_folder(service_id, template_folder_id):
     template_folder = current_service.get_template_folder_with_user_permission_or_403(template_folder_id, current_user)
@@ -456,7 +462,7 @@ def manage_template_folder(service_id, template_folder_id):
     )
 
 
-@main.route("/services/<service_id>/templates/folders/<template_folder_id>/delete", methods=['GET', 'POST'])
+@main.route("/services/<uuid:service_id>/templates/folders/<uuid:template_folder_id>/delete", methods=['GET', 'POST'])
 @user_has_permissions('manage_templates')
 def delete_template_folder(service_id, template_folder_id):
     template_folder = current_service.get_template_folder_with_user_permission_or_403(template_folder_id, current_user)
@@ -498,9 +504,14 @@ def delete_template_folder(service_id, template_folder_id):
         return manage_template_folder(service_id, template_folder_id)
 
 
-@main.route("/services/<service_id>/templates/add-<template_type>", methods=['GET', 'POST'])
-@main.route("/services/<service_id>/templates/folders/<template_folder_id>/add-<template_type>",
-            methods=['GET', 'POST'])
+@main.route(
+    "/services/<uuid:service_id>/templates/add-<template_type>",
+    methods=['GET', 'POST'],
+)
+@main.route(
+    "/services/<uuid:service_id>/templates/folders/<uuid:template_folder_id>/add-<template_type>",
+    methods=['GET', 'POST'],
+)
 @user_has_permissions('manage_templates')
 def add_service_template(service_id, template_type, template_folder_id=None):
 
@@ -544,7 +555,6 @@ def add_service_template(service_id, template_type, template_folder_id=None):
             notification_type=template_type,
             template_folder_id=template_folder_id,
             return_to='templates',
-            template_id='0'
         ))
     else:
         return render_template(
@@ -561,7 +571,7 @@ def abort_403_if_not_admin_user():
         abort(403)
 
 
-@main.route("/services/<service_id>/templates/<template_id>/edit", methods=['GET', 'POST'])
+@main.route("/services/<uuid:service_id>/templates/<uuid:template_id>/edit", methods=['GET', 'POST'])
 @user_has_permissions('manage_templates')
 def edit_service_template(service_id, template_id):
     template = current_service.get_template_with_user_permission_or_403(template_id, current_user)
@@ -643,7 +653,7 @@ def edit_service_template(service_id, template_id):
         )
 
 
-@main.route("/services/<service_id>/templates/<template_id>/delete", methods=['GET', 'POST'])
+@main.route("/services/<uuid:service_id>/templates/<uuid:template_id>/delete", methods=['GET', 'POST'])
 @user_has_permissions('manage_templates')
 def delete_service_template(service_id, template_id):
     template = current_service.get_template_with_user_permission_or_403(template_id, current_user)
@@ -691,7 +701,7 @@ def delete_service_template(service_id, template_id):
     )
 
 
-@main.route("/services/<service_id>/templates/<template_id>/redact", methods=['GET'])
+@main.route("/services/<uuid:service_id>/templates/<uuid:template_id>/redact", methods=['GET'])
 @user_has_permissions('manage_templates')
 def confirm_redact_template(service_id, template_id):
     template = current_service.get_template_with_user_permission_or_403(template_id, current_user)
@@ -714,7 +724,7 @@ def confirm_redact_template(service_id, template_id):
     )
 
 
-@main.route("/services/<service_id>/templates/<template_id>/redact", methods=['POST'])
+@main.route("/services/<uuid:service_id>/templates/<uuid:template_id>/redact", methods=['POST'])
 @user_has_permissions('manage_templates')
 def redact_template(service_id, template_id):
 
@@ -732,7 +742,7 @@ def redact_template(service_id, template_id):
     ))
 
 
-@main.route('/services/<service_id>/templates/<template_id>/versions')
+@main.route('/services/<uuid:service_id>/templates/<uuid:template_id>/versions')
 @user_has_permissions('view_activity')
 def view_template_versions(service_id, template_id):
     return render_template(
@@ -754,7 +764,7 @@ def view_template_versions(service_id, template_id):
     )
 
 
-@main.route('/services/<service_id>/templates/<template_id>/set-template-sender', methods=['GET', 'POST'])
+@main.route('/services/<uuid:service_id>/templates/<uuid:template_id>/set-template-sender', methods=['GET', 'POST'])
 @user_has_permissions('manage_templates')
 def set_template_sender(service_id, template_id):
     template = current_service.get_template_with_user_permission_or_403(template_id, current_user)
@@ -784,7 +794,7 @@ def set_template_sender(service_id, template_id):
     )
 
 
-@main.route('/services/<service_id>/templates/<template_id>/edit-postage', methods=['GET', 'POST'])
+@main.route('/services/<uuid:service_id>/templates/<uuid:template_id>/edit-postage', methods=['GET', 'POST'])
 @user_has_permissions('manage_templates')
 def edit_template_postage(service_id, template_id):
     template = current_service.get_template_with_user_permission_or_403(template_id, current_user)