Validate log level values, format unsupported level errors in a more human-friendly way

deps/rabbitmq_cli/lib/rabbitmq/cli/ctl/commands/set_log_level_command.ex

@@ -17,13 +17,18 @@ defmodule RabbitMQ.CLI.Ctl.Commands.SetLogLevelCommand do
   alias RabbitMQ.CLI.Core.Helpers
 
   @behaviour RabbitMQ.CLI.CommandBehaviour
-  use RabbitMQ.CLI.DefaultOutput
+  @known_levels ["debug", "info", "notice", "warning", "error", "critical", "alert", "emergency", "none"]
 
   def merge_defaults(args, opts), do: {args, opts}
 
   def validate([], _), do: {:validation_failure, :not_enough_args}
   def validate([_|_] = args, _) when length(args) > 1, do: {:validation_failure, :too_many_args}
-  def validate([_], _), do: :ok
+  def validate([level], _) do
+    case Enum.member?(@known_levels, level) do
+      true  -> :ok
+      false -> {:error, "level #{level} is not supported. Try one of debug, info, warning, error, none"}
+    end
+  end
 
   use RabbitMQ.CLI.Core.RequiresRabbitAppRunning
 
@@ -35,4 +40,10 @@ defmodule RabbitMQ.CLI.Ctl.Commands.SetLogLevelCommand do
   def usage, do: "set_log_level <log_level>"
 
   def banner([log_level], _), do: "Setting log level to \"#{log_level}\" ..."
+
+  def output({:error, {:invalid_log_level, level}}, _opts) do
+    {:error, RabbitMQ.CLI.Core.ExitCodes.exit_software,
+     "level #{level} is not supported. Try one of debug, info, warning, error, none"}
+  end
+  use RabbitMQ.CLI.DefaultOutput
 end

deps/rabbitmq_cli/test/set_log_level_command_test.exs

@@ -11,8 +11,7 @@
 ## The Original Code is RabbitMQ.
 ##
 ## The Initial Developer of the Original Code is GoPivotal, Inc.
-## Copyright (c) 2007-2016 Pivotal Software, Inc.  All rights reserved.
-
+## Copyright (c) 2007-2018 Pivotal Software, Inc.  All rights reserved.
 
 defmodule SetLogLevelCommandTest do
   use ExUnit.Case, async: false
@@ -27,10 +26,14 @@ defmodule SetLogLevelCommandTest do
       opts: %{node: get_rabbit_hostname()}}
   end
 
-  test "validate: with one argument succeeds", context do
+  test "validate: with a single known level succeeds", context do
     assert @command.validate([context[:log_level]], context[:opts]) == :ok
   end
 
+  test "validate: with a single unsupported level fails", context do
+    assert match?({:error, _}, @command.validate(["lolwut"], context[:opts]))
+  end
+
   test "validate: with extra arguments returns an arg count error", context do
     assert @command.validate([context[:log_level], "whoops"], context[:opts]) == {:validation_failure, :too_many_args}
   end