Handle messages without data (#99)

Messages with payloadFormat: "NONE" may not contain the data attribute.

Note something may have changed on Google's side because I believe this was previously handled by the nil check.

The nil data case was originally fixed in #14 so I am leaving the explicit match for messages with nil data. The attribute match will cover the cases where no data attribute exists on the payload.

lib/broadway_cloud_pub_sub/pull_client.ex

@@ -167,12 +167,13 @@ defmodule BroadwayCloudPubSub.PullClient do
     end
   end
 
-  defp decode_message(%{"data" => nil} = message), do: message
-
-  defp decode_message(%{"data" => encoded_data} = message) do
+  defp decode_message(%{"data" => encoded_data} = message) when is_binary(encoded_data) do
     %{message | "data" => Base.decode64!(encoded_data)}
   end
 
+  defp decode_message(%{"data" => nil} = message), do: message
+  defp decode_message(%{"attributes" => %{"payloadFormat" => "NONE"}} = message), do: message
+
   defp headers(config) do
     token = get_token(config)
     [{"authorization", "Bearer #{token}"}, {"content-type", "application/json"}]

test/broadway_cloud_pub_sub/pull_client_test.exs

@@ -79,6 +79,23 @@ defmodule BroadwayCloudPubSub.PullClientTest do
   }
   """
 
+  @no_payload_response """
+  {
+    "receivedMessages": [
+      {
+        "ackId": "1",
+        "message": {
+          "attributes": {
+            "payloadFormat": "NONE"
+          },
+          "messageId": "20240501001",
+          "publishTime": "2024-05-01T13:07:41.716Z"
+        }
+      }
+    ]
+  }
+  """
+
   setup do
     server = Bypass.open()
     base_url = "http://localhost:#{server.port}"
@@ -155,6 +172,20 @@ defmodule BroadwayCloudPubSub.PullClientTest do
       assert message.metadata.orderingKey == "key1"
     end
 
+    test "returns a list of Broadway.Message when payloadFormat is NONE", %{
+      opts: base_opts,
+      server: server
+    } do
+      on_pubsub_request(server, fn _, _ ->
+        {:ok, @no_payload_response}
+      end)
+
+      {:ok, opts} = PullClient.init(base_opts)
+
+      assert [message] = PullClient.receive_messages(10, & &1, opts)
+      assert message.metadata.messageId == "20240501001"
+    end
+
     test "returns a list of Broadway.Message with :data and :metadata set", %{
       opts: base_opts
     } do