def test_reproduce():
test_ecosystem_configuration = get_test_ecosystem_configuration()
test_ecosystem_configuration.lion_reproduce_birth_rate = 0.1
test_ecosystem_configuration.maximum_lion_population = 109
test_ecosystem_configuration.gazelle_net_reproduce_rate = 0.2
test_ecosystem_configuration.maximum_gazelle_population = 1441
test_ecosystem_configuration.grass_net_reproduce_rate = 0.3
test_ecosystem_configuration.maximum_grass_population = 3381
model = ecosystem.EcosystemModel(test_ecosystem_configuration)
model.reset(100, 1000, 2000)
assert model._lion_population == 100
assert model._gazelle_population == 1000
assert model._grass_population == 2000
# reproduce without lion reproduction
model.step(0.0, 0.0)
assert model._lion_population == 100
assert model._gazelle_population == 1200
assert model._grass_population == 2600
# reproduce with 80% lion reproduction
model.step(0.8, 0.0)
assert model._lion_population == 108
assert model._gazelle_population == 1440
assert model._grass_population == 3380
# reproduce capped by maximum population
model.step(1.0, 0.0)
assert model._lion_population == 109
assert model._gazelle_population == 1441
assert model._grass_population == 3381
def test_hunt():
test_ecosystem_configuration = get_test_ecosystem_configuration()
test_ecosystem_configuration.lion_hunt_rate = 0.1
test_ecosystem_configuration.maximum_lion_food = 9
model = ecosystem.EcosystemModel(test_ecosystem_configuration)
model.reset(100, 1000, 0)
assert model._lion_food == 0
assert model._lion_population == 100
assert model._gazelle_population == 1000
# step without lion hunting
model.step(0.0, 0.0)
assert model._lion_food == 0
assert model._lion_population == 100
assert model._gazelle_population == 1000
# step with 80% lion hunting
model.step(0.0, 0.8)
assert model._lion_food == 8
assert model._lion_population == 100
assert model._gazelle_population == 992
# excess of maximum food is lost
model.step(0.0, 0.8)
assert model._lion_food == 9
assert model._lion_population == 100
assert model._gazelle_population == 984
def test_lion_death():
test_ecosystem_configuration = get_test_ecosystem_configuration()
test_ecosystem_configuration.lion_death_rate = 0.1
model = ecosystem.EcosystemModel(test_ecosystem_configuration)
model.reset(100, 0, 0)
assert model._lion_population == 100
model.step(0.0, 0.0)
assert model._lion_population == 90
def test_init_sim():
test_ecosystem_configuration = get_test_ecosystem_configuration()
model = ecosystem.EcosystemModel(test_ecosystem_configuration)
assert model.ecosystem_configuration == test_ecosystem_configuration
assert model._lion_population == 0
assert model._lion_food == 0
assert model._gazelle_population == 0
assert model._grass_population == 0
model.reset(1, 2, 3)
assert model._lion_population == 1
assert model._gazelle_population == 2
assert model._grass_population == 3
def test_gazelle_food():
test_ecosystem_configuration = get_test_ecosystem_configuration()
test_ecosystem_configuration.gazelle_food_consumption = 0.1
model = ecosystem.EcosystemModel(test_ecosystem_configuration)
model.reset(0, 100, 15)
assert model._gazelle_population == 100
assert model._grass_population == 15
model.step(0.0, 0.0)
assert model._gazelle_population == 100
assert model._grass_population == 5
model.step(0.0, 0.0)
assert model._gazelle_population == 50
assert model._grass_population == 0
def test_lion_food():
test_ecosystem_configuration = get_test_ecosystem_configuration()
test_ecosystem_configuration.lion_food_consumption = 0.1
model = ecosystem.EcosystemModel(test_ecosystem_configuration)
model.reset(100, 0, 0)
assert model._lion_food == 10
assert model._lion_population == 100
model.step(0.0, 0.0)
assert model._lion_food == 0
assert model._lion_population == 100
model.step(0.0, 0.0)
assert model._lion_food == 0
assert model._lion_population == 0
def test_sustainable_default_configuration():
# verify that a stable state is possible where all populations rise using the default configuration
config = ecosystem.EcosystemConfiguration()
model = ecosystem.EcosystemModel(config)
# this may need to be adjusted whenever the base simulation is changed
model.reset(1000, 3000, 9000)
initial_lion_population = model._lion_population
initial_lion_food = model._lion_food
initial_gazelle_population = model._gazelle_population
initial_grass_population = model._grass_population
reproduce_slightly_above_death_rate = (
config.lion_death_rate + 0.05) / config.lion_reproduce_birth_rate
hunt_slightly_above_food_consumption = (config.lion_food_consumption +
0.05) / config.lion_hunt_rate
model.step(reproduce_slightly_above_death_rate,
hunt_slightly_above_food_consumption)
assert model._lion_population > initial_lion_population
assert is_whole_number(model._lion_population)
assert model._lion_food > initial_lion_food
assert model._gazelle_population > initial_gazelle_population
assert is_whole_number(model._gazelle_population)
assert model._grass_population > initial_grass_population
assert is_whole_number(model._grass_population)