[Finch] Change error handling, fix for response stream (#573)

lib/tesla/adapter/finch.ex

@@ -69,8 +69,11 @@ if Code.ensure_loaded?(Finch) do
         {:ok, %Finch.Response{status: status, headers: headers, body: body}} ->
           {:ok, %Tesla.Env{env | status: status, headers: headers, body: body}}
 
-        {:error, mint_error} ->
-          {:error, Exception.message(mint_error)}
+        {:error, %Mint.TransportError{reason: reason}} ->
+          {:error, reason}
+
+        {:error, reason} ->
+          {:error, reason}
       end
     end
 

test/tesla/adapter/finch_test.exs

@@ -25,4 +25,22 @@ defmodule Tesla.Adapter.FinchTest do
     start_supervised!({Finch, opts})
     :ok
   end
+
+  test "Delay request" do
+    request = %Env{
+      method: :head,
+      url: "#{@http}/delay/1"
+    }
+
+    assert {:error, :timeout} = call(request, receive_timeout: 100)
+  end
+
+  test "Delay request with stream" do
+    request = %Env{
+      method: :head,
+      url: "#{@http}/delay/1"
+    }
+
+    assert {:error, :timeout} = call(request, receive_timeout: 100, response: :stream)
+  end
 end