update blog post, and run credo with 'pi'

app/test/firehose_web/controllers/blog_test.exs

@@ -74,7 +74,7 @@ defmodule FirehoseWeb.BlogTest do
       conn = get(conn, "/api/blog/engineering")
       assert %{"blog" => "engineering", "posts" => posts} = json_response(conn, 200)
       assert is_list(posts)
-      assert length(posts) > 0
+      refute Enum.empty?(posts)
     end
 
     test "GET /api/blog/engineering/:slug returns a post", %{conn: conn} do
@@ -99,7 +99,7 @@ defmodule FirehoseWeb.BlogTest do
       conn = get(conn, "/api/blog/releases")
       assert %{"blog" => "release_notes", "posts" => posts} = json_response(conn, 200)
       assert is_list(posts)
-      assert length(posts) > 0
+      refute Enum.empty?(posts)
     end
 
     test "GET /api/blog/releases/:slug returns a post", %{conn: conn} do