from FluidSim.FluidSimulator import FluidSimulator2D
import numpy as np


def test_stand_still():
    fs = FluidSimulator2D(50, 50)

    fs.array.has_fluid[10, 10] = True

    for i in range(100):
        fs.timestep(0)

    assert fs.array.has_fluid[10, 10], "Fluid not on the same spot anymore"
    assert np.sum(fs.array.has_fluid * 1.0) == 1.0, "Fluid amount changed"


def test_move_positive_x():
    fs = FluidSimulator2D(50, 50)

    fs.array.has_fluid[10, 10] = True
    fs.array.u_x[10, 10] = 1.0
    fs.array.u_x[11, 10] = 1.0
    # fs.array.u_x[9, 10] = -1.0

    for i in range(10):
        fs.timestep(0)
        assert np.sum(fs.array.has_fluid * 1.0) == 1.0, "Fluid amount changed"

    assert fs.array.has_fluid[0, 10], "Fluid not on the right border"