Confusion about ExUnit doctests and escape codes

Questions / Help
1

Hi

I am dabbling a bit with parser combinators. And one of the parsers i need is one for escaped characters. When trying to write doctests for it i failed miserably. Took me quite some time to realize the problem is the way doctests handle backslashes.

The following doctest succeeds for me:

defmodule Doctest do

  @moduledoc """
  iex> "\$"
  "$"
  iex> "\\$"
  "$"

  iex> "\\\$"
  "$"
  iex> "\\\$"
  "\$"
  iex> "\\\$"
  "\\$"
  iex> "\\\$"
  "\\\$"

  iex> "\\\\$"
  "\\\\$"
  """
end

And i have trouble explaining to myself why it does. Why do three backslashes vanish and four suddenly matter completely.

Anyone with insights?

1 Like
2

Shot in the dark: try using the non-interpolation heredoc syntax for @moduledoc:

@moduledoc ~S"""
...your tests here
"""
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