metadata_matches supports array

lib/logger_file_backend.ex

@@ -145,6 +145,17 @@ defmodule LoggerFileBackend do
   # all of the filter keys are present
   def metadata_matches?(_md, []), do: true
 
+  def metadata_matches?(md, [{key, [_ | _] = val} | rest]) do
+    case Keyword.fetch(md, key) do
+      {:ok, md_val} ->
+        (md_val in val) && metadata_matches?(md, rest)
+
+      # fail on first mismatch
+      _ ->
+        false
+    end
+  end
+
   def metadata_matches?(md, [{key, val} | rest]) do
     case Keyword.fetch(md, key) do
       {:ok, ^val} ->

test/logger_file_backend_test.exs

@@ -43,6 +43,8 @@ defmodule LoggerFileBackendTest do
   test "metadata_matches?" do
     # exact match
     assert metadata_matches?([a: 1], a: 1) == true
+    # included in array match
+    assert metadata_matches?([a: 1], a: [1, 2]) == true
     # total mismatch
     assert metadata_matches?([b: 1], a: 1) == false
     # default to allow