Made tests pass, Floki updated to allow encoding of special characters of entities, update readability to disable this.

lib/readability.ex

@@ -213,7 +213,7 @@ defmodule Readability do
   """
   @spec raw_html(html_tree) :: binary
   def raw_html(html_tree) do
-    html_tree |> Floki.raw_html()
+    html_tree |> Floki.raw_html(encode: false)
   end
 
   def parse(raw_html) when is_binary(raw_html), do: Floki.parse(raw_html)

mix.exs

@@ -40,7 +40,7 @@ defmodule Readability.Mixfile do
   # Type "mix help deps" for more examples and options
   defp deps do
     [
-      {:floki, "~> 0.18.0"},
+      {:floki, "~> 0.20"},
       {:httpoison, "~> 0.13.0"},
       {:ex_doc, "~> 0.14", only: :dev},
       {:credo, "~> 0.6.1", only: [:dev, :test]},

mix.lock

@@ -1,11 +1,13 @@
-%{"bunt": {:hex, :bunt, "0.2.0", "951c6e801e8b1d2cbe58ebbd3e616a869061ddadcc4863d0a2182541acae9a38", [:mix], []},
+%{
+  "bunt": {:hex, :bunt, "0.2.0", "951c6e801e8b1d2cbe58ebbd3e616a869061ddadcc4863d0a2182541acae9a38", [:mix], []},
   "certifi": {:hex, :certifi, "2.0.0", "a0c0e475107135f76b8c1d5bc7efb33cd3815cb3cf3dea7aefdd174dabead064", [:rebar3], []},
   "credo": {:hex, :credo, "0.6.1", "a941e2591bd2bd2055dc92b810c174650b40b8290459c89a835af9d59ac4a5f8", [:mix], [{:bunt, "~> 0.2.0", [hex: :bunt, optional: false]}]},
   "dialyxir": {:hex, :dialyxir, "0.5.1", "b331b091720fd93e878137add264bac4f644e1ddae07a70bf7062c7862c4b952", [:mix], []},
   "earmark": {:hex, :earmark, "1.2.3", "206eb2e2ac1a794aa5256f3982de7a76bf4579ff91cb28d0e17ea2c9491e46a4", [:mix], []},
   "ex_doc": {:hex, :ex_doc, "0.16.3", "cd2a4cfe5d26e37502d3ec776702c72efa1adfa24ed9ce723bb565f4c30bd31a", [:mix], [{:earmark, "~> 1.1", [hex: :earmark, optional: false]}]},
-  "floki": {:hex, :floki, "0.18.1", "6f903e3074357fe9756079d0f607e430589912f698b5c5e5970af08daba1537c", [:mix], [{:mochiweb, "~> 2.15", [hex: :mochiweb, optional: false]}]},
+  "floki": {:hex, :floki, "0.20.3", "dfb3a71eb99938e330b4156433d55c6d0b188d936c9683d115a8540bac56e019", [:mix], [{:html_entities, "~> 0.4.0", [hex: :html_entities, optional: false]}, {:mochiweb, "~> 2.15", [hex: :mochiweb, optional: false]}]},
   "hackney": {:hex, :hackney, "1.9.0", "51c506afc0a365868469dcfc79a9d0b94d896ec741cfd5bd338f49a5ec515bfe", [:rebar3], [{:certifi, "2.0.0", [hex: :certifi, optional: false]}, {:idna, "5.1.0", [hex: :idna, optional: false]}, {:metrics, "1.0.1", [hex: :metrics, optional: false]}, {:mimerl, "1.0.2", [hex: :mimerl, optional: false]}, {:ssl_verify_fun, "1.1.1", [hex: :ssl_verify_fun, optional: false]}]},
+  "html_entities": {:hex, :html_entities, "0.4.0", "f2fee876858cf6aaa9db608820a3209e45a087c5177332799592142b50e89a6b", [:mix], []},
   "httpoison": {:hex, :httpoison, "0.13.0", "bfaf44d9f133a6599886720f3937a7699466d23bb0cd7a88b6ba011f53c6f562", [:mix], [{:hackney, "~> 1.8", [hex: :hackney, optional: false]}]},
   "idna": {:hex, :idna, "5.1.0", "d72b4effeb324ad5da3cab1767cb16b17939004e789d8c0ad5b70f3cea20c89a", [:rebar3], [{:unicode_util_compat, "0.3.1", [hex: :unicode_util_compat, optional: false]}]},
   "meck": {:hex, :meck, "0.8.7", "ebad16ca23f685b07aed3bc011efff65fbaf28881a8adf925428ef5472d390ee", [:rebar3], []},
@@ -14,4 +16,5 @@
   "mochiweb": {:hex, :mochiweb, "2.15.0", "e1daac474df07651e5d17cc1e642c4069c7850dc4508d3db7263a0651330aacc", [:rebar3], []},
   "mock": {:hex, :mock, "0.2.1", "bfdba786903e77f9c18772dee472d020ceb8ef000783e737725a4c8f54ad28ec", [:mix], [{:meck, "~> 0.8.2", [hex: :meck, optional: false]}]},
   "ssl_verify_fun": {:hex, :ssl_verify_fun, "1.1.1", "28a4d65b7f59893bc2c7de786dec1e1555bd742d336043fe644ae956c3497fbe", [:make, :rebar], []},
-  "unicode_util_compat": {:hex, :unicode_util_compat, "0.3.1", "a1f612a7b512638634a603c8f401892afbf99b8ce93a45041f8aaca99cadb85e", [:rebar3], []}}
+  "unicode_util_compat": {:hex, :unicode_util_compat, "0.3.1", "a1f612a7b512638634a603c8f401892afbf99b8ce93a45041f8aaca99cadb85e", [:rebar3], []},
+}