Merge pull request #55 from amatalai/follow-redirects-improvement

Follow redirects improvement

lib/tesla/middleware/follow_redirects.ex

@@ -1,14 +1,16 @@
 defmodule Tesla.Middleware.FollowRedirects do
-  @doc """
+  @moduledoc """
   Follow 301/302 redirects
 
   Example:
+      defmodule MyClient do
+        use Tesla
 
-  defmodule MyClient do
-    use Tesla
+        plug Tesla.Middleware.FollowRedirects, max_redirects: 3 # defaults to 5
+      end
 
-    plug Tesla.Middleware.FollowRedirects, max_redirects: 3 # defaults to 5
-  end
+  **NOTE** For `httpc` adapter you have to explicitely disable default autoredirection
+      adapter :httpc, autoredirect: false
   """
   @max_redirects 5
   @redirect_statuses [301, 302, 307, 308]
@@ -19,8 +21,13 @@ defmodule Tesla.Middleware.FollowRedirects do
     redirect(env, next, max)
   end
 
-  defp redirect(_env, _next, left) when left <= 0 do
-    raise Tesla.Error, "too many redirects"
+  defp redirect(env, next, left) when left == 0 do
+    case Tesla.run(env, next) do
+      %{status: status} = env when not status in @redirect_statuses ->
+        env
+      _ ->
+        raise Tesla.Error, "too many redirects"
+    end
   end
 
   defp redirect(env, next, left) do

test/tesla/middleware/follow_redirects_test.exs

@@ -0,0 +1,60 @@
+defmodule FollowRedirectsTest do
+  use ExUnit.Case
+
+  use Tesla.Middleware.TestCase, middleware: Tesla.Middleware.FollowRedirects
+
+  defmodule Client do
+    use Tesla
+
+    plug Tesla.Middleware.FollowRedirects
+
+    adapter fn (env) ->
+      {status, headers, body} = case env.url do
+        "/0" ->
+          {200, %{'Content-Type' => 'text/plain'}, "foo bar"}
+        "/" <> n ->
+          next = String.to_integer(n) - 1
+          {301, %{'Location' => '/#{next}'}, ""}
+      end
+
+      %{env | status: status, headers: headers, body: body}
+    end
+  end
+
+  test "redirects if default max redirects isn't exceeded" do
+    assert Client.get("/5").status == 200
+  end
+
+  test "raise error when redirect default max redirects is exceeded" do
+    assert_raise(Tesla.Error, "too many redirects", fn-> Client.get("/6") end)
+  end
+
+  defmodule CustomMaxRedirectsClient do
+    use Tesla
+
+    plug Tesla.Middleware.FollowRedirects, max_redirects: 1
+
+    adapter fn (env) ->
+      {status, headers, body} = case env.url do
+        "/0" ->
+          {200, %{'Content-Type' => 'text/plain'}, "foo bar"}
+        "/" <> n ->
+          next = String.to_integer(n) - 1
+          {301, %{'Location' => '/#{next}'}, ""}
+      end
+
+      %{env | status: status, headers: headers, body: body}
+    end
+  end
+
+  alias CustomMaxRedirectsClient, as: CMRClient
+
+  test "redirects if custom max redirects isn't exceeded" do
+    assert CMRClient.get("/1").status == 200
+  end
+
+  test "raise error when custom max redirects is exceeded" do
+    assert_raise(Tesla.Error, "too many redirects", fn-> CMRClient.get("/2") end)
+  end
+
+end