Include context of prior command for Entity protocol interactions

lib/entity.ex

@@ -2,10 +2,9 @@ defprotocol HTTPact.Entity do
   @moduledoc """
   Provides a contract for an API Wrapper to convert responses into a return type.
   """
-  @fallback_to_any true
-  def from_response(response)
+  def from_response(source_command, response)
 end
 
-defimpl HTTPact.Entity, for: Any do
-  def from_response(response), do: response
+defimpl HTTPact.Entity, for: HTTPact.Request do
+  def from_response(%HTTPact.Request{}, response), do: response
 end

lib/httpact.ex

@@ -23,18 +23,28 @@ defmodule HTTPact do
 
   @spec execute(Request.t() | command(), http_client()) :: any
   def execute(%Request{} = request, client) when is_function(client) do
-    client.(request)
-    |> Entity.from_response()
+    with {:ok, response} <- client.(request) do
+      Entity.from_response(request, response)
+    else
+      {:error, _msg} = error -> error
+      :error -> {:error, "An unknown error occurred with the given HTTPact client"}
+    end
   end
 
   def execute(%Request{} = request, client) when is_atom(client) do
-    client.execute(request)
-    |> Entity.from_response()
+    with {:ok, response} <- client.execute(request) do
+      Entity.from_response(request, response)
+    else
+      {:error, _msg} = error -> error
+      :error -> {:error, "An unknown error occurred with the client: #{Atom.to_string(client)}"}
+    end
   end
 
   def execute(command, client) do
-    Command.to_request(command)
-    |> execute(client)
-    |> Entity.from_response()
+    response =
+      Command.to_request(command)
+      |> execute(client)
+
+    Entity.from_response(command, response)
   end
 end

test/httpact_test.exs

@@ -1,7 +1,7 @@
 defmodule HTTPactTest do
   use ExUnit.Case
   doctest HTTPact
-  HTTPact.{Request, Response}
+  alias HTTPact.{Request, Response}
 
   test "We can mock an HTTP Client with anonymous functions for testing API Wrappers" do
     # Build a function that knows how to return responses from matched requests
@@ -23,17 +23,12 @@ defmodule HTTPactTest do
       body: "test body",
       path: "https://testsite.test/tests",
       headers: [{"test", "header"}],
-      http_client: test_client,
     }
 
-    assert HTTPact.execute(request) == {:ok, %Response{
+    assert HTTPact.execute(request, test_client) == %Response{
       status: 200,
       body: "it's kind of alive!",
       headers: [{"test", "header"}],
-    }}
-  end
-
-  test "We can test an HTTP Client implementation by setting up a simple test server" do
-    assert false
+    }
   end
 end