Fix coverage

lib/logger_json/formatter/metadata.ex

@@ -18,7 +18,7 @@ defmodule LoggerJSON.Formatter.Metadata do
   end
 
   def update_metadata_selector({:from_application_env, other}, _processed_keys) do
-    raise """
+    raise ArgumentError, """
     Invalid value for `:metadata` option: `{:from_application_env, #{inspect(other)}}`.
 
     The value must be a tuple with the application and module name,

test/logger_json/formatter/metadata_test.exs

@@ -3,6 +3,49 @@ defmodule LoggerJSON.Formatter.MetadataTest do
   import LoggerJSON.Formatter.Metadata
 
   describe "update_metadata_selector/2" do
+    # test this
+    #     def update_metadata_selector({:from_application_env, {app, module}, path}, processed_keys) do
+    #   Application.fetch_env!(app, module)
+    #   |> get_in(path)
+    #   |> update_metadata_selector(processed_keys)
+    # end
+
+    # def update_metadata_selector({:from_application_env, {app, module}}, processed_keys) do
+    #   Application.fetch_env!(app, module)
+    #   |> update_metadata_selector(processed_keys)
+    # end
+
+    # def update_metadata_selector({:from_application_env, other}, _processed_keys) do
+    #   raise """
+    #   Invalid value for `:metadata` option: `{:from_application_env, #{inspect(other)}}`.
+
+    #   The value must be a tuple with the application and module name,
+    #   and an optional path to the metadata option.
+
+    #   Eg.: `{:from_application_env, {:logger, :default_formatter}, [:metadata]}`
+    #   """
+    # end
+
+    test "takes metadata from application env" do
+      Application.put_env(:logger_json, :test_metadata_key, [:foo])
+
+      assert update_metadata_selector({:from_application_env, {:logger_json, :test_metadata_key}}, []) ==
+               [:foo]
+
+      Application.put_env(:logger_json, :test_metadata_key, %{metadata: [:foo]})
+
+      assert update_metadata_selector({:from_application_env, {:logger_json, :test_metadata_key}, [:metadata]}, []) ==
+               [:foo]
+    end
+
+    test "raises if metadata is not a tuple with the application and module name" do
+      message = ~r/Invalid value for `:metadata` option: `{:from_application_env, :foo}`./
+
+      assert_raise ArgumentError, message, fn ->
+        update_metadata_selector({:from_application_env, :foo}, [])
+      end
+    end
+
     test "takes metadata :all rule and updates it to exclude the given keys" do
       assert update_metadata_selector(:all, [:ansi_color]) == {:all_except, [:ansi_color]}
     end