Use built-in Req stub for LastFm tests

lib/last_fm.ex

@@ -2,7 +2,7 @@ defmodule LastFm do
   def get_artist_info(musicbrainz_id, name) do
     last_fm_config = last_fm_config()
 
-    case last_fm_config.api.get_artist_info(
+    case LastFm.APIImpl.get_artist_info(
            {:musicbrainz_id, musicbrainz_id},
            last_fm_config
          ) do
@@ -12,7 +12,7 @@ defmodule LastFm do
       {:error, :invalid_parameters} ->
         # Sometimes the artist info cannot be identified with the MusicBrainz ID,
         # because Last.fm doesn't have that information. In that case, we try again with the artist name.
-        last_fm_config.api.get_artist_info({:name, name}, last_fm_config)
+        LastFm.APIImpl.get_artist_info({:name, name}, last_fm_config)
 
       error ->
         error
@@ -22,7 +22,7 @@ defmodule LastFm do
   def get_similar_artists(musicbrainz_id, name) do
     last_fm_config = last_fm_config()
 
-    case last_fm_config.api.get_similar_artists(
+    case LastFm.APIImpl.get_similar_artists(
            {:musicbrainz_id, musicbrainz_id},
            last_fm_config
          ) do
@@ -32,7 +32,7 @@ defmodule LastFm do
       {:error, :invalid_parameters} ->
         # Sometimes the artist info cannot be identified with the MusicBrainz ID,
         # because Last.fm doesn't have that information. In that case, we try again with the artist name.
-        last_fm_config.api.get_similar_artists({:name, name}, last_fm_config)
+        LastFm.APIImpl.get_similar_artists({:name, name}, last_fm_config)
 
       error ->
         error

lib/last_fm/api_impl.ex

@@ -102,6 +102,7 @@ defmodule LastFm.APIImpl do
       ],
       user_agent: config.user_agent
     )
+    |> Req.Request.merge_options(config.req_options)
     |> Req.Request.put_private(:api_key, config.api_key)
     |> Req.Request.append_request_steps(log_attempt: &log_attempt/1)
     |> Req.Request.append_response_steps(parse_error: &parse_error/1)
@@ -114,6 +115,9 @@ defmodule LastFm.APIImpl do
 
       {:ok, response} ->
         {:ok, response.body}
+
+      error ->
+        error
     end
   end
 

lib/last_fm/config.ex

@@ -5,7 +5,8 @@ defmodule LastFm.Config do
           user: String.t(),
           auto_refresh: boolean(),
           refresh_interval: pos_integer(),
-          user_agent: String.t()
+          user_agent: String.t(),
+          req_options: Keyword.t()
         }
 
   @enforce_keys [:api, :api_key, :user]
@@ -14,7 +15,8 @@ defmodule LastFm.Config do
             user: "",
             auto_refresh: true,
             refresh_interval: 60_000,
-            user_agent: "change me"
+            user_agent: "change me",
+            req_options: []
 
   @schema NimbleOptions.new!(
             api: [
@@ -43,6 +45,11 @@ defmodule LastFm.Config do
               type: :string,
               required: false,
               default: "change me"
+            ],
+            req_options: [
+              type: :keyword_list,
+              required: false,
+              default: []
             ]
           )