Added Elixir file example

tests/syntax-tests/source/Elixir/command.ex

@@ -0,0 +1,31 @@
+defmodule Charlex.Command do
+  @callback usage() :: [String.t()]
+
+  @callback description() :: String.t()
+
+  @callback parse_args(args :: String.t()) :: any()
+
+  @callback run(context :: Map.t(), args :: [String.t()] | any()) :: String.t() | any()
+
+  @optional_callbacks usage: 0, description: 0, parse_args: 1
+
+  defmacro __using__(_opts) do
+    quote do
+      @behaviour unquote(__MODULE__)
+
+      @impl true
+      def usage, do: "This command is without usage, will add it soon"
+
+      @impl true
+      def description, do: "This command is without description, will add it soon"
+
+      @impl true
+      def run(_context, _args), do: :ok
+
+      @impl true
+      def parse_args(args), do: args |> String.split() |> Kernel.tl()
+
+      defoverridable parse_args: 1, description: 0, run: 2, usage: 0
+    end
+  end
+end