Gracefully handle requests for non-feeds

lib/changelog/schema/feed.ex

@@ -23,6 +23,8 @@ defmodule Changelog.Feed do
 
   def get_by_slug(slug), do: Repo.get_by(__MODULE__, slug: slug)
 
+  def get_by_slug!(slug), do: Repo.get_by!(__MODULE__, slug: slug)
+
   def with_podcast_id(query \\ __MODULE__, id),
     do: from(q in query, where: fragment("? = ANY(?)", ^id, q.podcast_ids))
 

lib/changelog_web/feeds.ex

@@ -81,11 +81,7 @@ defmodule ChangelogWeb.Feeds do
 
   # Special case for "The Changelog" feed which gets its episodes from
   # News, Friends & Interviews
-  def generate("podcast") do
-    podcast = Podcast.changelog()
-    episodes = get_episodes(podcast)
-    render("podcast.xml", podcast: podcast, episodes: episodes)
-  end
+  def generate("podcast"), do: generate(Podcast.changelog())
 
   def generate(%Feed{} = feed) do
     episodes = get_episodes(feed)
@@ -99,7 +95,7 @@ defmodule ChangelogWeb.Feeds do
 
   # When we have an unknown slug, look for a podcast followed by a feed
   def generate(slug) do
-    generate(Podcast.get_by_slug(slug) || Feed.get_by_slug(slug))
+    generate(Podcast.get_by_slug(slug) || Feed.get_by_slug!(slug))
   end
 
   defp get_episodes(%Feed{} = feed) do

test/changelog_web/controllers/feed_controller_test.exs

@@ -77,6 +77,12 @@ defmodule ChangelogWeb.FeedControllerTest do
     assert conn.resp_body =~ e.title
   end
 
+  test "a podcast feed that doesn't exist", %{conn: conn} do
+    assert_raise Ecto.NoResultsError, fn ->
+      get(conn, ~p"/comments/feed")
+    end
+  end
+
   test "the plusplus feed with incorrect slug doesn't exist", %{conn: conn} do
     Application.put_env(:changelog, :plusplus_slug, "8675309")
     conn = get(conn, Routes.feed_path(conn, :plusplus, "justguessing"))
@@ -146,6 +152,12 @@ defmodule ChangelogWeb.FeedControllerTest do
     refute conn.resp_body =~ e3.title
   end
 
+  test "a custom feed that does not exist", %{conn: conn} do
+    assert_raise Ecto.NoResultsError, fn ->
+      get(conn, ~p"/feeds/8675309")
+    end
+  end
+
   test "the posts feed", %{conn: conn} do
     p1 = insert(:published_post)
     p2 = insert(:post)