Add echo body function

src/webtest.gleam

@@ -1,3 +1,4 @@
+import gleam/bit_array
 import gleam/bytes_builder
 import gleam/erlang/process
 import gleam/http
@@ -29,6 +30,11 @@ pub fn main() {
             on_close: fn(_state) { io.println("Goodbye!") },
             handler: handle_we_message,
           )
+        ["echo"] -> echo_body(req)
+        ["chunk"] -> serve_chunk(req)
+        ["file", ..rest] -> serve_file(req, rest)
+        ["form"] -> handle_form(req)
+
         _ -> not_found
       }
     }
@@ -60,3 +66,21 @@ fn handle_we_message(state, conn, message) {
     mist.Closed | mist.Shutdown -> actor.Stop(process.Normal)
   }
 }
+
+fn echo_body(request: Request(Connection)) -> Response(ResponseData) {
+  let content_type =
+    request
+    |> request.get_header("content-type")
+    |> result.unwrap("test/plain")
+
+  mist.read_body(request, 1024 * 1024 * 10)
+  |> result.map(fn(req) {
+    response.new(200)
+    |> response.set_body(mist.Bytes(bytes_builder.from_bit_array(req.body)))
+    |> response.set_header("content-type", content_type)
+  })
+  |> result.lazy_unwrap(fn() {
+    response.new(400)
+    |> response.set_body(mist.Bytes(bytes_builder.new()))
+  })
+}