     test "log_path" do
       add_to_application_env(:log_path, "log/appsignal.log")
       assert valid_configuration |> Map.put(:log_path, "log/appsignal.log") == init_config
+      assert "log/appsignal.log" == System.get_env("APPSIGNAL_LOG_FILE_PATH")
     end
 
     test "endpoint" do
       add_to_application_env(:endpoint, "https://push.staging.lol")
       assert valid_configuration |> Map.put(:endpoint, "https://push.staging.lol") == init_config
+      assert "https://push.staging.lol" == System.get_env("APPSIGNAL_PUSH_API_ENDPOINT")
     end
 
     test "running_in_container" do
       add_to_application_env(:running_in_container, true)
       assert valid_configuration |> Map.put(:running_in_container, true) == init_config
+      assert "true" == System.get_env("APPSIGNAL_RUNNING_IN_CONTAINER")
     end
 
     test "send_params" do

    assert default_configuration == init_config
  end

  describe "with a valid configuration" do
    setup do
      Application.put_env(
        :appsignal, :config,

    test "http_proxy" do
      add_to_application_env(:http_proxy, "http://10.10.10.10:8888")
      assert valid_configuration |> Map.put(:http_proxy, "http://10.10.10.10:8888") == init_config
      assert "http://10.10.10.10:8888" == System.get_env("APPSIGNAL_HTTP_PROXY")
    end

    test "ignore_actions" do
      actions = ~w(
          ExampleApplication.PageController#ignored
          ExampleApplication.PageController#also_ignored
      )
      add_to_application_env(:ignore_actions, actions)
      assert valid_configuration |> Map.put(:ignore_actions, actions) == init_config
      assert "ExampleApplication.PageController#ignored,ExampleApplication.PageController#also_ignored" == System.get_env("APPSIGNAL_IGNORE_ACTIONS")
    end

    test "ignore_errors" do
      errors = ~w(VerySpecificError AnotherError)
      add_to_application_env(:ignore_errors, errors)
      assert valid_configuration |> Map.put(:ignore_errors, errors) == init_config
      assert "VerySpecificError,AnotherError" == System.get_env("APPSIGNAL_IGNORE_ERRORS")
    end

    test "enable_host_metrics" do
      add_to_application_env(:enable_host_metrics, true)
      assert valid_configuration |> Map.put(:enable_host_metrics, true) == init_config
      assert "true" == System.get_env("APPSIGNAL_ENABLE_HOST_METRICS")
    end

    test "log" do
