From 778d58a7cec0071566b01d62ed2fe495dc4cc174 Mon Sep 17 00:00:00 2001
From: Wojtek Mach <wojtek@wojtekmach.pl>
Date: Mon, 19 Jun 2023 19:40:03 +0200
Subject: [PATCH] `decompress_body`: Support multiple `content-encoding`
 headers

Closes #191
---
 lib/req/steps.ex        | 23 ++++-------
 test/req/steps_test.exs | 87 +++++++++++++++++++++++++++++------------
 2 files changed, 70 insertions(+), 40 deletions(-)

diff --git a/lib/req/steps.ex b/lib/req/steps.ex
index 7fec24e3..2fe59df0 100644
--- a/lib/req/steps.ex
+++ b/lib/req/steps.ex
@@ -1487,25 +1487,18 @@ defmodule Req.Steps do
   ## Utilities
 
   defp get_content_encoding_header(headers) do
-    if value = get_header(headers, "content-encoding") do
-      value
-      |> String.downcase()
-      |> String.split(",", trim: true)
-      |> Stream.map(&String.trim/1)
-      |> Enum.reverse()
-    else
-      []
-    end
-  end
-
-  defp get_header(headers, name) do
-    Enum.find_value(headers, nil, fn {key, value} ->
-      if String.downcase(key) == name do
+    headers
+    |> Enum.flat_map(fn {name, value} ->
+      if String.downcase(name) == "content-encoding" do
         value
+        |> String.downcase()
+        |> String.split(",", trim: true)
+        |> Stream.map(&String.trim/1)
       else
-        nil
+        []
       end
     end)
+    |> Enum.reverse()
   end
 
   defp cache_path(cache_dir, request) do
diff --git a/test/req/steps_test.exs b/test/req/steps_test.exs
index 50fe4a4c..8468db31 100644
--- a/test/req/steps_test.exs
+++ b/test/req/steps_test.exs
@@ -246,37 +246,74 @@ defmodule Req.StepsTest do
 
   ## Response steps
 
-  test "decompress_body: gzip", c do
-    Bypass.expect(c.bypass, "GET", "/", fn conn ->
-      conn
-      |> Plug.Conn.put_resp_header("content-encoding", "x-gzip")
-      |> Plug.Conn.send_resp(200, :zlib.gzip("foo"))
-    end)
+  describe "decompress_body" do
+    test "gzip", c do
+      Bypass.expect(c.bypass, "GET", "/", fn conn ->
+        conn
+        |> Plug.Conn.put_resp_header("content-encoding", "x-gzip")
+        |> Plug.Conn.send_resp(200, :zlib.gzip("foo"))
+      end)
 
-    assert Req.get!(c.url).body == "foo"
-  end
+      assert Req.get!(c.url).body == "foo"
+    end
 
-  test "decompress_body: brotli", c do
-    Bypass.expect(c.bypass, "GET", "/", fn conn ->
-      {:ok, body} = :brotli.encode("foo")
+    test "multiple codecs", c do
+      Bypass.expect(c.bypass, "GET", "/", fn conn ->
+        conn
+        |> Plug.Conn.put_resp_header("content-encoding", "gzip, deflate")
+        |> Plug.Conn.send_resp(200, "foo" |> :zlib.gzip() |> :zlib.zip())
+      end)
 
-      conn
-      |> Plug.Conn.put_resp_header("content-encoding", "br")
-      |> Plug.Conn.send_resp(200, body)
-    end)
+      assert Req.get!(c.url).body == "foo"
+    end
 
-    assert Req.get!(c.url).body == "foo"
-  end
+    test "multiple codecs with multiple headers" do
+      {:ok, listen_socket} = :gen_tcp.listen(0, mode: :binary, active: false)
+      {:ok, port} = :inet.port(listen_socket)
 
-  @tag :capture_log
-  test "decompress_body: zstd", c do
-    Bypass.expect(c.bypass, "GET", "/", fn conn ->
-      conn
-      |> Plug.Conn.put_resp_header("content-encoding", "zstd")
-      |> Plug.Conn.send_resp(200, :ezstd.compress("foo"))
-    end)
+      Task.start_link(fn ->
+        {:ok, socket} = :gen_tcp.accept(listen_socket)
+        assert {:ok, "GET / HTTP/1.1\r\n" <> _} = :gen_tcp.recv(socket, 0)
 
-    assert Req.get!(c.url).body == "foo"
+        body = "foo" |> :zlib.gzip() |> :zlib.zip()
+
+        data = """
+        HTTP/1.1 200 OK
+        content-encoding: gzip
+        content-encoding: deflate
+        content-length: #{byte_size(body)}
+
+        #{body}
+        """
+
+        :ok = :gen_tcp.send(socket, data)
+      end)
+
+      assert Req.get!("http://localhost:#{port}").body == "foo"
+    end
+
+    test "brotli", c do
+      Bypass.expect(c.bypass, "GET", "/", fn conn ->
+        {:ok, body} = :brotli.encode("foo")
+
+        conn
+        |> Plug.Conn.put_resp_header("content-encoding", "br")
+        |> Plug.Conn.send_resp(200, body)
+      end)
+
+      assert Req.get!(c.url).body == "foo"
+    end
+
+    @tag :capture_log
+    test "zstd", c do
+      Bypass.expect(c.bypass, "GET", "/", fn conn ->
+        conn
+        |> Plug.Conn.put_resp_header("content-encoding", "zstd")
+        |> Plug.Conn.send_resp(200, :ezstd.compress("foo"))
+      end)
+
+      assert Req.get!(c.url).body == "foo"
+    end
   end
 
   @tag :tmp_dir