Add option parser and tests for it

TESTS!!!!

issues/.formatter.exs

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+# Used by "mix format"
+[
+  inputs: ["{mix,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
+]

issues/.gitignore

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+# The directory Mix will write compiled artifacts to.
+/_build/
+
+# If you run "mix test --cover", coverage assets end up here.
+/cover/
+
+# The directory Mix downloads your dependencies sources to.
+/deps/
+
+# Where third-party dependencies like ExDoc output generated docs.
+/doc/
+
+# Ignore .fetch files in case you like to edit your project deps locally.
+/.fetch
+
+# If the VM crashes, it generates a dump, let's ignore it too.
+erl_crash.dump
+
+# Also ignore archive artifacts (built via "mix archive.build").
+*.ez
+
+# Ignore package tarball (built via "mix hex.build").
+issues-*.tar
+
+# Temporary files, for example, from tests.
+/tmp/

issues/README.md

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+# Issues
+
+**TODO: Add description**
+
+## Installation
+
+If [available in Hex](https://hex.pm/docs/publish), the package can be installed
+by adding `issues` to your list of dependencies in `mix.exs`:
+
+```elixir
+def deps do
+  [
+    {:issues, "~> 0.1.0"}
+  ]
+end
+```
+
+Documentation can be generated with [ExDoc](https://github.com/elixir-lang/ex_doc)
+and published on [HexDocs](https://hexdocs.pm). Once published, the docs can
+be found at [https://hexdocs.pm/issues](https://hexdocs.pm/issues).
+

issues/lib/issues.ex

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+defmodule Issues do
+  @moduledoc """
+  Documentation for `Issues`.
+  """
+
+  @doc """
+  Hello world.
+
+  ## Examples
+
+      iex> Issues.hello()
+      :world
+
+  """
+  def hello do
+    :world
+  end
+end

issues/lib/issues/cli.ex

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+defmodule Issues.CLI do
+  @default_count 4
+
+  @moduledoc """
+  Handle the command line parsing and the dispatch to the various functions that end up
+  generating a table of the last _n_ issues in a github project.
+  """
+
+  def run(argv) do
+    parse_args(argv)
+  end
+
+  def parse_args(argv) do
+    parse =
+      OptionParser.parse(argv,
+        switches: [help: :boolean],
+        aliases: [h: :help]
+      )
+
+    case parse do
+      {[help: true], _, _} ->
+        :help
+
+      {_, [user, project, count], _} ->
+        {user, project, String.to_integer(count)}
+
+      {_, [user, project], _} ->
+        {user, project, @default_count}
+
+      _ ->
+        :help
+    end
+  end
+end

issues/mix.exs

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+defmodule Issues.MixProject do
+  use Mix.Project
+
+  def project do
+    [
+      app: :issues,
+      version: "0.1.0",
+      elixir: "~> 1.12",
+      start_permanent: Mix.env() == :prod,
+      deps: deps()
+    ]
+  end
+
+  # Run "mix help compile.app" to learn about applications.
+  def application do
+    [
+      extra_applications: [:logger]
+    ]
+  end
+
+  # Run "mix help deps" to learn about dependencies.
+  defp deps do
+    [
+      # {:dep_from_hexpm, "~> 0.3.0"},
+      # {:dep_from_git, git: "https://github.com/elixir-lang/my_dep.git", tag: "0.1.0"}
+    ]
+  end
+end

issues/test/cli_test.exs

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+defmodule CliTest do
+  use ExUnit.Case
+  doctest Issues
+
+  import Issues.CLI, only: [parse_args: 1]
+
+  test ":help returned by option parsing the -h and --help options" do
+    assert parse_args(["-h", "anything"]) == :help
+    assert parse_args(["--help", "anything"]) == :help
+  end
+
+  test "three values returned if three given" do
+    assert parse_args(["user", "project", "99"]) == {"user", "project", 99}
+  end
+
+  test "two values and default count returned if two values given" do
+    assert parse_args(["user", "project"]) == {"user", "project", 4}
+  end
+end

issues/test/issues_test.exs

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+defmodule IssuesTest do
+  use ExUnit.Case
+  doctest Issues
+
+  test "greets the world" do
+    assert Issues.hello() == :world
+  end
+end

issues/test/test_helper.exs

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+ExUnit.start()