@testset "Propagator" begin

  println("Testing propagator")

  using Thesis: prop_one

  # Set up
  start_mass = 10_000.
  start = gen_orbit(rand(.5year : hour : 2year), start_mass)
  stepsize = rand(hour : second : 6hour)

  # Test that Laguerre-Conway is the default propagator for spacecrafts
  state = prop_one([0., 0., 0.], start, no_thrust, stepsize)
  @test laguerre_conway(start, stepsize) ≈ state[1:6]
  @test state[7] == start_mass

  # Test that mass is reduced properly
  state = prop_one([1., 0., 0.], start, bepi, stepsize)
  @test state[7] == start_mass - mfr(bepi)*stepsize
  
end