User documentation is in “Intervalo melódico”.

Here is a minimal lesson file:

header {
  module = melodicinterval
  version = "3.1.4"
  title = "Seconds and thirds"
  ask_for_intervals_0 = 1, 2, 3, 4, -1, -2, -3, -4
  test = "3x"
  test_requirement = "90%"
}

Additional variables you can put in the header. Click on the link to get an explanation:

Tests are only partially implemented for the melodicinterval exercise module: tests where each question is made by more than one interval does not work yet.