fix: legacy log level handling to support atom values for backward compatibility

Author: yordis

lib/tesla/middleware/logger.ex

@@ -314,10 +314,15 @@ defmodule Tesla.Middleware.Logger do
   end
 
   # Wrapper function to adapt old log_level functions to the new response tuple format
-  defp legacy_log_level_wrapper(log_level_function, {:ok, env}) do
+  defp legacy_log_level_wrapper(log_level_function, {:ok, env})
+       when is_function(log_level_function) do
     log_level_function.(env)
   end
 
+  defp legacy_log_level_wrapper(log_level_atom, {:ok, _env}) when is_atom(log_level_atom) do
+    log_level_atom
+  end
+
   defp legacy_log_level_wrapper(_log_level_function, {:error, _}) do
     :error
   end

test/tesla/middleware/logger_test.exs

@@ -337,6 +337,62 @@ defmodule Tesla.Middleware.LoggerTest do
 
       assert output =~ ":log_level option is deprecated"
     end
+
+    test "log_level with atom value still works (backward compatibility)" do
+      Logger.configure(level: :debug)
+
+      warning_output =
+        ExUnit.CaptureIO.capture_io(:stderr, fn ->
+          client =
+            Tesla.client(
+              [
+                {Tesla.Middleware.Logger, log_level: :debug}
+              ],
+              fn env -> {:ok, %{env | status: 200}} end
+            )
+
+          log_output = capture_log(fn -> Tesla.get(client, "/test") end)
+          assert log_output =~ "[debug] GET /test -> 200"
+        end)
+
+      assert warning_output =~ ":log_level option is deprecated"
+    end
+
+    test "log_level with atom value for warning levels" do
+      warning_output =
+        ExUnit.CaptureIO.capture_io(:stderr, fn ->
+          client =
+            Tesla.client(
+              [
+                {Tesla.Middleware.Logger, log_level: :warn}
+              ],
+              fn env -> {:ok, %{env | status: 200}} end
+            )
+
+          log = capture_log(fn -> Tesla.get(client, "/test") end)
+          assert log =~ "[warning] GET /test -> 200"
+        end)
+
+      assert warning_output =~ ":log_level option is deprecated"
+    end
+
+    test "log_level with atom value handles error responses" do
+      warning_output =
+        ExUnit.CaptureIO.capture_io(:stderr, fn ->
+          client =
+            Tesla.client(
+              [
+                {Tesla.Middleware.Logger, log_level: :info}
+              ],
+              fn _env -> {:error, :connection_failed} end
+            )
+
+          log = capture_log(fn -> Tesla.get(client, "/test") end)
+          assert log =~ "[error] GET /test -> error: :connection_failed"
+        end)
+
+      assert warning_output =~ ":log_level option is deprecated"
+    end
   end
 
   alias Tesla.Middleware.Logger.Formatter