Elixir projections

.projections.json

{
  "lib/*.ex": {
    "alternate": "test/{}_test.exs",
    "type": "source"
  },
  "test/*_test.exs": {
    "alternate": "lib/{}.ex",
    "make": "mix test {file}",
    "type": "test"
  },
  "mix.exs": {
    "alternate": "mix.lock",
    "type": "mix"
  },
  "mix.lock": {
    "alternate": "mix.exs"
  },
  "*": {
    "console": "iex -S mix"
  }
}