Twitter user sees channel specific twitter card

lib/tilex_web/models/post.ex

@@ -70,6 +70,12 @@ defmodule Tilex.Post do
     |> String.downcase
   end
 
+  def twitter_description(post) do
+    post.body
+    |> String.split("\n")
+    |> hd
+  end
+
   defp add_slug(changeset) do
     case get_field(changeset, :slug) do
       nil ->

lib/tilex_web/templates/layout/app.html.eex

@@ -20,8 +20,8 @@
     <meta name="twitter:site" content="@hashrockettil">
     <meta name="twitter:creator" content="@hashrockettil">
     <meta name="twitter:title" content="Today I Learned: a Hashrocket Project">
-    <meta name="twitter:description" content="TIL is an open-source project by Hashrocket that exists to catalogue the sharing & accumulation of knowledge as it happens day-to-day. Posts have a 200-word limit, and posting is open to any Rocketeer as well as select friends of the team. We hope you enjoy learning along with us.">
-    <meta name="twitter:image" content=<%= TilexWeb.Endpoint.static_url() <> "/assets/til_twittercard.png" %>>
+    <meta name="twitter:description" content="<%= twitter_description(assigns[:post]) %>">
+    <meta name="twitter:image" content=<%= twitter_image_url(assigns[:post]) %>>
 
     <link href='//fonts.googleapis.com/css?family=Raleway:700,900' rel='stylesheet' type='text/css'>
     <link href='//fonts.googleapis.com/css?family=Lora:400,700italic,700,400italic' rel='stylesheet' type='text/css'>

lib/tilex_web/views/layout_view.ex

@@ -6,4 +6,36 @@ defmodule TilexWeb.LayoutView do
   def page_title(%{developer: developer}), do: developer.username
   def page_title(%{page_title: page_title}), do: page_title
   def page_title(_), do: Application.get_env(:tilex, :organization_name)
+
+  def twitter_image_url(%Tilex.Post{} = post) do
+    channel_name = channel_name(post)
+
+    case File.exists?("assets/static/assets/#{channel_name}_twitter_card.png") do
+      true -> twitter_image_url(channel_name)
+      false -> twitter_image_url(nil)
+    end
+  end
+  def twitter_image_url(name) when is_binary(name) do
+    TilexWeb.Endpoint.static_url() <> "/assets/#{name}_twitter_card.png}"
+  end
+  def twitter_image_url(name) when is_nil(name) do
+    TilexWeb.Endpoint.static_url() <> "/assets/til_twittercard.png"
+  end
+
+  defp channel_name(post) do
+    case Ecto.assoc_loaded?(post.channel) do
+      true -> String.replace(post.channel.name, "-", "_")
+      false -> nil
+    end
+  end
+
+  def twitter_description(%Tilex.Post{} = post) do
+    Tilex.Post.twitter_description(post)
+  end
+
+  def twitter_description(_post) do
+    """
+TIL is an open-source project by Hashrocket that exists to catalogue the sharing & accumulation of knowledge as it happens day-to-day. Posts have a 200-word limit, and posting is open to any Rocketeer as well as select friends of the team. We hope you enjoy learning along with us.
+    """
+  end
 end

test/features/visitor_views_post_test.exs

@@ -9,7 +9,7 @@ defmodule VisitorViewsPostTest do
 
   test "the page shows a post", %{session: session} do
     developer = Factory.insert!(:developer)
-    channel = Factory.insert!(:channel, name: "awesomeness")
+    channel = Factory.insert!(:channel, name: "command-line")
     post = Factory.insert!(:post,
       title: "A special post",
       body: "This is how to be super awesome!",
@@ -22,7 +22,7 @@ defmodule VisitorViewsPostTest do
     |> PostShowPage.expect_post_attributes(%{
       title: "A special post",
       body: "This is how to be super awesome!",
-      channel: "#awesomeness",
+      channel: "#command-line",
       likes_count: 1
     })
 
@@ -60,6 +60,25 @@ defmodule VisitorViewsPostTest do
     assert url =~ "#{post.slug}-alternate-also-cool-title"
   end
 
+  test "and sees a channel specific twitter card and a post specific twitter description", %{session: session} do
+    popular_channel = Factory.insert!(:channel, name: "command-line")
+    post = Factory.insert!(:post, channel: popular_channel, body: "One sentence that sets up the post.\nAnother sentence that is more informative")
+
+    image_url = session
+           |> visit(post_path(Endpoint, :show, post))
+           |> find(Query.css("meta[name='twitter:image']", visible: false))
+           |> Element.attr("content")
+
+    assert image_url =~ "command_line_twitter_card.png"
+
+    twitter_description = session
+           |> find(Query.css("meta[name='twitter:description']", visible: false))
+           |> Element.attr("content")
+
+    assert twitter_description =~ "One sentence that sets up the post."
+    refute twitter_description =~ "Another sentence"
+  end
+
   test "and clicks 'like' for that post", %{session: session} do
     developer = Factory.insert!(:developer)
     post = Factory.insert!(:post, title: "A special post", developer: developer, likes: 1)

test/support/pages/navigation.ex

@@ -2,8 +2,11 @@ defmodule Tilex.Integration.Pages.Navigation do
   use Wallaby.DSL
 
   def ensure_heading(session, text) do
-    session
-    |> Browser.find(Query.css("header.site_head div h1", text: text))
+    heading = session
+    |> Browser.find(Query.css("header.site_head div h1"))
+    |> Element.text
+
+    ExUnit.Assertions.assert(heading =~ ~r/#{text}/i, "Expected: #{text}, Found: #{heading}")
 
     session
   end

test/support/pages/post_show_page.ex

@@ -34,10 +34,15 @@ defmodule Tilex.Integration.Pages.PostShowPage do
     session
     |> Browser.find(Query.css(".post .copy", text: expected_body))
 
-    session
-    |> Browser.find(
-         Query.css(".post aside .post__tag-link", text: String.upcase(expected_channel))
-       )
+    channel_name =
+      session
+      |> Browser.find(Query.css(".post aside .post__tag-link"))
+      |> Element.text()
+
+    ExUnit.Assertions.assert(
+      channel_name =~ ~r/#{expected_channel}/i,
+      "Unable to find text channel #{expected_channel}, instead found #{channel_name}"
+    )
 
     session
     |> Browser.find(Query.css(".js-like-action", text: expected_likes_count))