defmodule Blogex.MutationConfigTest do
  # The mutation sensor is opt-in: a dependency and two aliases, deliberately
  # absent from `make verify`'s VERIFY_SENSORS. These pins keep the wiring
  # honest (dev/test only, never runtime) and keep the aliases reading the
  # scope files rather than duplicating a list in mix.exs.
  use ExUnit.Case

  test "muex is a dev/test-only, non-runtime dependency" do
    deps = Mix.Project.config()[:deps]

    assert {:muex, requirement, opts} = dep!(deps, :muex)
    assert requirement =~ "0.12"
    assert opts[:only] == [:dev, :test]
    assert opts[:runtime] == false
  end

  test "mutate and mutate.fast aliases are defined" do
    aliases = Mix.Project.config()[:aliases]

    assert is_function(aliases[:mutate], 1)
    assert is_function(aliases[:"mutate.fast"], 1)
  end

  test "mutation args always include the scope, the curated mutators and --fail-at 0" do
    args = Blogex.MixProject.mutation_args("mutation_scope_fast.txt", [])
    scope = Blogex.MixProject.read_mutation_scope("mutation_scope_fast.txt")

    assert "--fail-at" in args
    assert Enum.at(args, Enum.find_index(args, &(&1 == "--fail-at")) + 1) == "0"
    assert files_arg(args) == Enum.join(scope, ",")

    mutators = Enum.at(args, Enum.find_index(args, &(&1 == "--mutators")) + 1)

    assert mutators ==
             "arithmetic,boolean,comparison,conditional,function_call,literal,return_value"
  end

  test "extra CLI args pass through so a single file can be targeted" do
    args =
      Blogex.MixProject.mutation_args("mutation_scope_fast.txt", ["--files", "lib/blogex/seo.ex"])

    assert args
           |> Enum.chunk_every(2, 1, :discard)
           |> Enum.any?(fn
             ["--files", "lib/blogex/seo.ex"] -> true
             _ -> false
           end)
  end

  test "an empty scope fails loudly instead of running over nothing" do
    path =
      Path.join(System.tmp_dir!(), "muex-empty-scope-#{System.unique_integer([:positive])}.txt")

    File.write!(path, "\n   \n")
    on_exit(fn -> File.rm(path) end)

    assert_raise Mix.Error, ~r/empty/, fn ->
      Blogex.MixProject.read_mutation_scope(path)
    end
  end

  defp dep!(deps, name) do
    case Enum.find(deps, fn
           {^name, _requirement} -> true
           {^name, _requirement, _opts} -> true
           _ -> false
         end) do
      {^name, requirement} -> {name, requirement, []}
      {^name, requirement, opts} -> {name, requirement, opts}
      nil -> flunk("expected #{inspect(name)} in deps/0")
    end
  end

  defp files_arg(args) do
    args
    |> Enum.chunk_every(2, 1, :discard)
    |> Enum.find_value(fn
      ["--files", files] -> files
      _ -> nil
    end)
  end
end