Added a basic CLI

lib/elixir_rss/cli.ex

@@ -0,0 +1,43 @@
+defmodule ElixirRss.CLI do
+  @default_host "0.0.0.0"
+  @default_port 8080
+  @default_basepath "/"
+
+  def run(argv) do
+    parse_args(argv)
+    |> process()
+  end
+
+  def parse_args(argv) do
+    OptionParser.parse(
+      argv,
+      strict: [help: :boolean,
+               host: :string,
+               port: :integer,
+               path: :string],
+      aliases: [h: :help])
+    |> elem(0)
+    |> switches_to_internal()
+  end
+
+  defp switches_to_internal(kwargs) do
+    if Keyword.get(kwargs, :help) do
+      :help
+    else
+      {Keyword.get(kwargs, :host, @default_host),
+       Keyword.get(kwargs, :port, @default_port),
+       Keyword.get(kwargs, :path, @default_basepath)}
+    end
+  end
+
+  defp process(:help) do
+    IO.puts("""
+      usage: elixir_rss [--host HOST] [--port PORT] [--path BASEPATH]
+      """)
+    System.halt(0)
+  end
+
+  defp process({host, port, path}) do
+    IO.puts("Host: #{host}, Port: #{port}, Basepath: #{path}")
+  end
+end

lib/elixir_rss/http.ex

@@ -1,4 +1,4 @@
-defmodule ElixirRss.Fetch do
+defmodule ElixirRss.Http do
   def fetch(url) do
     url
     |> HTTPoison.get()

test/cli_test.exs

@@ -0,0 +1,31 @@
+defmodule CliTest do
+  use ExUnit.Case
+  doctest ElixirRss
+
+  import ElixirRss.CLI, only: [parse_args: 1]
+
+  test ":help returned for -h, --help, and default" do
+    assert parse_args(["-h"]) == :help
+    assert parse_args(["--help"]) == :help
+    assert parse_args(["other", "-h", "stuff"]) == :help
+    assert parse_args(["other", "--help", "stuff"]) == :help
+  end
+
+  test "all switches given" do
+    assert parse_args(["--host", "127.0.0.1", "--port", "80", "--path", "/path"]) == {"127.0.0.1", 80, "/path"}
+  end
+
+  test "defaults returned for missing args" do
+    assert parse_args([]) == {"0.0.0.0", 8080, "/"}
+    assert parse_args(["--host", "127.0.0.1"]) == {"127.0.0.1", 8080, "/"}
+    assert parse_args(["--port", "80"]) == {"0.0.0.0", 80, "/"}
+    assert parse_args(["--path", "/path"]) == {"0.0.0.0", 8080, "/path"}
+    assert parse_args(["--host", "127.0.0.1", "--port", "80"]) == {"127.0.0.1", 80, "/"}
+    assert parse_args(["--host", "127.0.0.1", "--path", "/path"]) == {"127.0.0.1", 8080, "/path"}
+    assert parse_args(["--port", "80", "--path", "/path"]) == {"0.0.0.0", 80, "/path"}
+  end
+
+  test "out of order switches" do
+    assert parse_args(["--port", "80", "--host", "127.0.0.1", "--path", "/path"]) == {"127.0.0.1", 80, "/path"}
+  end
+end

test/fetch_rss_test.exs

@@ -1,8 +1,8 @@
-defmodule ElixirRss.FetchTest do
+defmodule HttpTest do
   use ExUnit.Case
-  doctest ElixirRss.Fetch
+  doctest ElixirRss
 
   test "fetch url" do
-    assert ElixirRss.Fetch.fetch("https://shillerben.com") |> elem(0) == :ok
+    assert ElixirRss.Http.fetch("https://shillerben.com") |> elem(0) == :ok
   end
 end