Avoid raising on undefined protocol in Msgpax.pack/1 (#54)

lexmag · Dec 10, 2020 · 8251397 · 8251397
1 parent 28fa446
commit 8251397
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Showing 2 changed files with 8 additions and 1 deletion.
diff --git a/lib/msgpax.ex b/lib/msgpax.ex
@@ -62,7 +62,7 @@ defmodule Msgpax do
       {:ok, <<163, 102, 111, 111>>}
 
   """
-  @spec pack(term, Keyword.t()) :: {:ok, iodata} | {:error, Msgpax.PackError.t()}
+  @spec pack(term, Keyword.t()) :: {:ok, iodata} | {:error, Msgpax.PackError.t() | Exception.t()}
   def pack(term, options \\ []) when is_list(options) do
     iodata? = Keyword.get(options, :iodata, true)
 
@@ -71,6 +71,9 @@ defmodule Msgpax do
     catch
       :throw, reason ->
         {:error, %Msgpax.PackError{reason: reason}}
+
+      :error, %Protocol.UndefinedError{protocol: Msgpax.Packer} = exception ->
+        {:error, exception}
     else
       iodata when iodata? ->
         {:ok, iodata}

diff --git a/test/msgpax_test.exs b/test/msgpax_test.exs
@@ -179,6 +179,10 @@ defmodule MsgpaxTest do
              {:error, %PackError{reason: {:not_encodable, <<5::3>>}}}
   end
 
+  test "protocol not implemented" do
+    assert {:error, %Protocol.UndefinedError{}} = Msgpax.pack([{}])
+  end
+
   test "pack!/2 with the :iodata option" do
     assert Msgpax.pack!([], iodata: true) == [144]
     assert Msgpax.pack!([], iodata: false) == <<144>>