Add CLI command characters show to show a saved character

Of note, we had to duplicate some helper functions from
`characters_test.exs` to `custom_parsers_test.exs`. It'd be desirable if
these could be shared utility methods that multiple tests can use.
However to do so we either need to include the test helper functions in
the package libary code _or_ create some test macros. The former is
undersireable as I don't believe testing helpers should generally be
distributed as part of the library. The latter is more technical than we
need at this point in time. Sometime in the future we are likely to move
to the latter option.

lib/cli/args.ex

@@ -17,4 +17,15 @@ defmodule ExTTRPGDev.CLI.Args do
       ]
     ]
   end
+
+  def character do
+    [
+      character: [
+        value_name: "CHARACTER",
+        help: "A saved character, e.g. misu_park",
+        required: true,
+        parser: &CustomParsers.character_parser(&1)
+      ]
+    ]
+  end
 end

lib/cli/characters.ex

@@ -32,6 +32,11 @@ defmodule ExTTRPGDev.CLI.Characters do
           list: [
             name: "list",
             about: "List saved characters"
+          ],
+          show: [
+            name: "show",
+            about: "Show information for a character",
+            args: Args.character()
           ]
         ]
       ]
@@ -68,4 +73,10 @@ defmodule ExTTRPGDev.CLI.Characters do
         Enum.each(characters, fn character -> IO.puts("- #{character}") end)
     end
   end
+
+  def handle_characters_subcommands([:show | _subcommands], %Optimus.ParseResult{
+        args: %{character: character}
+      }) do
+    IO.inspect(character)
+  end
 end

lib/cli/custom_parsers.ex

@@ -3,6 +3,7 @@ defmodule ExTTRPGDev.CLI.CustomParsers do
   Custom parsers to be used with Optimus args :parse
   """
   alias ExTTRPGDev.RuleSystems
+  alias ExTTRPGDev.Characters
 
   @doc """
   Parses a string of dice specifications seperated by commas
@@ -37,4 +38,15 @@ defmodule ExTTRPGDev.CLI.CustomParsers do
        "\"#{system}\" is not configured, run `ex_ttrpg_dev systems list` to list configured systems"}
     end
   end
+
+  def character_parser(character_slug) when is_bitstring(character_slug) do
+    if Characters.character_exists?(character_slug) do
+      character_slug
+      |> Characters.load_character!()
+      |> Kernel.then(fn loaded_character -> {:ok, loaded_character} end)
+    else
+      {:error,
+       "Character matching \"#{character_slug}\" was not found, run `ex_ttrpg_dev characters list` to list existing characters"}
+    end
+  end
 end

test/custom_parsers_test.exs

@@ -1,19 +1,53 @@
 defmodule ExTTRPGDevTest.CLI.CustomParsers do
   use ExUnit.Case
 
+  alias ExTTRPGDev.Characters
+  alias ExTTRPGDev.Characters.Character
   alias ExTTRPGDev.CLI.CustomParsers
+  alias ExTTRPGDev.RuleSystems
   alias ExTTRPGDev.RuleSystems.RuleSystem
 
   doctest ExTTRPGDev.CLI.CustomParsers,
     except: [
       system_parser: 1
     ]
 
+  def build_test_character do
+    RuleSystems.list_systems()
+    |> List.first()
+    |> RuleSystems.load_system!()
+    |> Character.gen_character!()
+  end
+
+  def save_test_character do
+    character = build_test_character()
+    Characters.save_character!(character)
+    character
+  end
+
+  def delete_test_character(%Character{} = character) do
+    File.rm(Characters.character_file_path!(character))
+  end
+
   def system_parser_test do
     # If no error was raised, then all is good
     {:ok, %RuleSystem{}} = CustomParsers.system_parser("dnd_5e_srd")
 
     # Should raise an error
     assert_raise RuntimeError, CustomParsers.system_parser("unknown_system")
   end
+
+  def character_parser_test do
+    character = save_test_character()
+
+    {:ok, %Character{}} = CustomParsers.character_parser(character.metadata.slug)
+
+    # cleanup
+    delete_test_character(character)
+
+    # should raise an error
+    assert_raise RuntimeError, CustomParsers.character_parser(character.metadata.slug)
+
+    assert False
+  end
 end