Fix Dialyzer errors

lib/console.ex

@@ -13,11 +13,8 @@ defmodule Artificery.Console do
   @doc """
   Terminates the process with the given status code.
   """
-  @spec halt(non_neg_integer) :: :ok | no_return
-  def halt(code)
-
-  def halt(0), do: :ok
-  def halt(code) when code > 0 do
+  @spec halt(non_neg_integer()) :: no_return()
+  def halt(code) do
     if Application.get_env(:artificery, :no_halt, false) do
       # During tests we don't want to kill the node process,
       # exit the test process instead.
@@ -277,14 +274,14 @@ defmodule Artificery.Console do
   @spec init() :: :ok
   def init do
     # For logger state
-    :ets.new(__MODULE__, [:public, :set, :named_table])
+    __MODULE__ = :ets.new(__MODULE__, [:public, :set, :named_table])
     # Start listening for console events
     Events.start
     :ok
   end
 
   @doc false
-  @spec width() :: non_neg_integer
+  @spec width() :: pos_integer()
   def width do
     case :io.columns() do
       {:error, :enotsup} -> 80

lib/console/color.ex

@@ -26,7 +26,7 @@ defmodule Artificery.Console.Color do
 
   Returns a formatted binary.
   """
-  @spec style(binary, [atom]) :: binary
+  @spec style(iodata, [atom]) :: binary
   def style(msg, styles) when is_list(styles) do
     do_style(Enum.uniq(styles), [msg], false)
   end

lib/console/events.ex

@@ -43,7 +43,7 @@ defmodule Artificery.Console.Events do
     # is changed. The default action is to ignore it.
     # If a program does full-screen display, it should handle SIGWINCH. When the signal
     # arrives, it should fetch the new screen size and reformat its display accordingly.
-    notify(subscribers, :sigwinch)
+    :ok = notify(subscribers, :sigwinch)
     {:ok, subscribers}
   end
   def handle_event(_, subscribers), do: {:ok, subscribers}
@@ -69,7 +69,7 @@ defmodule Artificery.Console.Events do
 
   @impl :gen_event
   def handle_info({:DOWN, _ref, _type, pid, _reason}, subscribers) do
-    {:noreply, Map.delete(subscribers, pid)}
+    {:ok, Map.delete(subscribers, pid)}
   end
 
   @impl :gen_event
@@ -87,5 +87,7 @@ defmodule Artificery.Console.Events do
     for {pid, _} <- subscribers do
       send(pid, {:event, event})
     end
+
+    :ok
   end
 end

lib/console/prompt.ex

@@ -67,12 +67,14 @@ defmodule Artificery.Console.Prompt do
 
   # TODO: Open EDITOR to a temp file, read in result when closed
   @doc false
-  @spec edit() :: String.t
+  # @spec edit() :: String.t
+  @spec edit() :: no_return()
   def edit(), do: exit(:not_implemented)
 
   # TODO: Choose from a selection of options
   @doc false
-  @spec choose(String.t, [String.t]) :: String.t
+  # @spec choose(String.t, [String.t]) :: String.t
+  @spec choose(String.t, [String.t]) :: no_return()
   def choose(question, choices) when is_binary(question) and is_list(choices) do
     exit(:not_implemented)
   end

lib/console/spinner.ex

@@ -124,7 +124,7 @@ defmodule Artificery.Console.Spinner do
   end
   def handle_cast({:stop, status}, data) do
     Artificery.Console.Events.unsubscribe
-    render(set_status(data, status))
+    _ = render(set_status(data, status))
     IO.write @cursor_show
     {:stop, :normal, nil}
   end
@@ -135,7 +135,7 @@ defmodule Artificery.Console.Spinner do
   end
 
   defp render(%{text: text, status: status} = data) do
-    clear(data)
+    data = clear(data)
     {frame_data, data} = frame(data)
     output = "#{frame_data} #{text} #{status}\n"
     IO.write(output)

lib/entry.ex

@@ -31,6 +31,7 @@ defmodule Artificery.Entry do
       Handles parsing and validating arguments, then dispatching the selected
       command.
       """
+      @spec main() :: no_return()
       def main() do
         argv =
           :init.get_plain_arguments()
@@ -42,6 +43,7 @@ defmodule Artificery.Entry do
       end
 
       @doc false
+      @spec main(OptionParser.argv()) :: no_return()
       def main(argv) when is_list(argv) do
         Console.init()
 
@@ -88,7 +90,7 @@ defmodule Artificery.Entry do
           |> Enum.map(fn {name, val} -> {name, apply_transform(@global_options[name], val)} end)
           |> Map.new()
 
-        Console.configure(verbosity: Map.get(global_flags, :verbose, :normal))
+        _ = Console.configure(verbosity: Map.get(global_flags, :verbose, :normal))
 
         case argv do
           [] ->
@@ -285,18 +287,7 @@ defmodule Artificery.Entry do
       end
 
       defp dispatch(%Command{name: command_name, callback: callback} = command, argv, flags) do
-        new_flags =
-          case __MODULE__.pre_dispatch(command, argv, flags) do
-            {:ok, new_flags} ->
-              new_flags
-
-            other ->
-              Console.error(
-                "Expected {:ok, options} returned from #{__MODULE__}.pre_dispatch/3, got: #{
-                  inspect(other)
-                }"
-              )
-          end
+        {:ok, new_flags} = __MODULE__.pre_dispatch(command, argv, flags)
 
         if function_exported?(__MODULE__, callback, 2) do
           apply(__MODULE__, callback, [argv, new_flags])
@@ -321,6 +312,7 @@ defmodule Artificery.Entry do
         end
       end
 
+      @spec print_help(list(String.t())) :: no_return()
       defp print_help([]) do
         # Print global help
 
@@ -343,7 +335,7 @@ defmodule Artificery.Entry do
 
         for {flag, help} <- global_options do
           IO.write([flag, String.duplicate(" ", max(flag_width - byte_size(flag) + 2, 2))])
-          print_help_lines(help, flag_width + 2)
+          :ok = print_help_lines(help, flag_width + 2)
         end
 
         IO.write([?\n, "COMMANDS\n\n"])
@@ -452,22 +444,22 @@ defmodule Artificery.Entry do
 
           for {flag, help} <- options do
             IO.write([flag, String.duplicate(" ", max(flag_width - byte_size(flag) + 2, 2))])
-            print_help_lines(help, flag_width + 2)
+            :ok = print_help_lines(help, flag_width + 2)
           end
 
           if has_args?, do: IO.write("\n")
         end
 
         # Print arguments
-        if has_args? do
+        _ = if has_args? do
           IO.write("ARGUMENTS\n")
 
           arguments = format_arguments(cmd.arguments)
           {arg_width, help_width} = column_widths(arguments)
 
           for {arg, help} <- arguments do
             IO.write([arg, String.duplicate(" ", max(arg_width - byte_size(arg) + 2, 2))])
-            print_help_lines(help, arg_width + 2)
+            :ok = print_help_lines(help, arg_width + 2)
           end
         end
 
@@ -500,6 +492,8 @@ defmodule Artificery.Entry do
         for line <- rest do
           IO.write([String.duplicate(" ", leading_width), line, ?\n])
         end
+
+        :ok
       end
 
       defp format_arguments(args) do

mix.exs

@@ -14,6 +14,10 @@ defmodule Artificery.MixProject do
       description: description(),
       package: package(),
       elixirc_paths: elixirc_paths(Mix.env),
+      dialyzer: [
+        flags: ["-Wunmatched_returns", :error_handling, :race_conditions, :underspecs],
+        plt_add_apps: [:mix]
+      ],
       preferred_cli_env: [
         docs: :docs,
         "hex.publish": :docs,
@@ -28,6 +32,7 @@ defmodule Artificery.MixProject do
 
   defp deps do
     [
+      {:dialyxir, "~> 1.0", only: [:dev], runtime: false},
       {:ex_doc, ">= 0.0.0", only: [:docs], runtime: false},
       {:eqc_ex, "~> 1.4", only: [:test], runtime: false}
     ]
@@ -55,5 +60,6 @@ defmodule Artificery.MixProject do
   end
 
   defp elixirc_paths(:test), do: ["lib", "test/support"]
+  defp elixirc_paths(:dev), do: ["lib", "test/artificery/dummy"]
   defp elixirc_paths(_), do: ["lib"]
 end

mix.lock

@@ -1,7 +1,9 @@
 %{
+  "dialyxir": {:hex, :dialyxir, "1.1.0", "c5aab0d6e71e5522e77beff7ba9e08f8e02bad90dfbeffae60eaf0cb47e29488", [:mix], [{:erlex, ">= 0.2.6", [hex: :erlex, repo: "hexpm", optional: false]}], "hexpm", "07ea8e49c45f15264ebe6d5b93799d4dd56a44036cf42d0ad9c960bc266c0b9a"},
   "earmark": {:hex, :earmark, "1.4.4", "4821b8d05cda507189d51f2caeef370cf1e18ca5d7dfb7d31e9cafe6688106a4", [:mix], [], "hexpm", "1f93aba7340574847c0f609da787f0d79efcab51b044bb6e242cae5aca9d264d"},
   "earmark_parser": {:hex, :earmark_parser, "1.4.12", "b245e875ec0a311a342320da0551da407d9d2b65d98f7a9597ae078615af3449", [:mix], [], "hexpm", "711e2cc4d64abb7d566d43f54b78f7dc129308a63bc103fbd88550d2174b3160"},
   "eqc_ex": {:hex, :eqc_ex, "1.4.2", "c89322cf8fbd4f9ddcb18141fb162a871afd357c55c8c0198441ce95ffe2e105", [:mix], [], "hexpm", "6547e68351624ca5387df7e3332136b07f1be73c5a429c1b4e40436dcad50f38"},
+  "erlex": {:hex, :erlex, "0.2.6", "c7987d15e899c7a2f34f5420d2a2ea0d659682c06ac607572df55a43753aa12e", [:mix], [], "hexpm", "2ed2e25711feb44d52b17d2780eabf998452f6efda104877a3881c2f8c0c0c75"},
   "ex_doc": {:hex, :ex_doc, "0.23.0", "a069bc9b0bf8efe323ecde8c0d62afc13d308b1fa3d228b65bca5cf8703a529d", [:mix], [{:earmark_parser, "~> 1.4.0", [hex: :earmark_parser, repo: "hexpm", optional: false]}, {:makeup_elixir, "~> 0.14", [hex: :makeup_elixir, repo: "hexpm", optional: false]}], "hexpm", "f5e2c4702468b2fd11b10d39416ddadd2fcdd173ba2a0285ebd92c39827a5a16"},
   "makeup": {:hex, :makeup, "1.0.5", "d5a830bc42c9800ce07dd97fa94669dfb93d3bf5fcf6ea7a0c67b2e0e4a7f26c", [:mix], [{:nimble_parsec, "~> 0.5 or ~> 1.0", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "cfa158c02d3f5c0c665d0af11512fed3fba0144cf1aadee0f2ce17747fba2ca9"},
   "makeup_elixir": {:hex, :makeup_elixir, "0.15.1", "b5888c880d17d1cc3e598f05cdb5b5a91b7b17ac4eaf5f297cb697663a1094dd", [:mix], [{:makeup, "~> 1.0", [hex: :makeup, repo: "hexpm", optional: false]}, {:nimble_parsec, "~> 1.1", [hex: :nimble_parsec, repo: "hexpm", optional: false]}], "hexpm", "db68c173234b07ab2a07f645a5acdc117b9f99d69ebf521821d89690ae6c6ec8"},

test/artificery/dummy/dummy.ex

@@ -0,0 +1,5 @@
+defmodule Artificery.Test.Dummy do
+  @moduledoc "A dummy module used to unveil Dialyzer errors"
+
+  use Artificery
+end