Files
python/exercises/practice/react/react_test.py
2021-01-29 11:14:36 -05:00

203 lines
6.7 KiB
Python

import unittest
from functools import partial
from react import InputCell, ComputeCell
# Tests adapted from `problem-specifications//canonical-data.json` @ v2.0.0
class ReactTest(unittest.TestCase):
def test_input_cells_have_a_value(self):
input_ = InputCell(10)
self.assertEqual(input_.value, 10)
def test_can_set_input_cell_value(self):
input_ = InputCell(4)
input_.value = 20
self.assertEqual(input_.value, 20)
def test_compute_cells_calculate_initial_value(self):
input_ = InputCell(1)
output = ComputeCell([input_], lambda inputs: inputs[0] + 1)
self.assertEqual(output.value, 2)
def test_compute_cells_take_inputs_in_right_order(self):
one = InputCell(1)
two = InputCell(2)
output = ComputeCell(
[one, two],
lambda inputs: inputs[0] + inputs[1]*10
)
self.assertEqual(output.value, 21)
def test_compute_cells_update_value_when_dependencies_are_changed(self):
input_ = InputCell(1)
output = ComputeCell([input_], lambda inputs: inputs[0] + 1)
input_.value = 3
self.assertEqual(output.value, 4)
def test_compute_cells_can_depend_on_other_compute_cells(self):
input_ = InputCell(1)
times_two = ComputeCell([input_], lambda inputs: inputs[0] * 2)
times_thirty = ComputeCell([input_], lambda inputs: inputs[0] * 30)
output = ComputeCell(
[times_two, times_thirty],
lambda inputs: inputs[0] + inputs[1]
)
self.assertEqual(output.value, 32)
input_.value = 3
self.assertEqual(output.value, 96)
def test_compute_cells_fire_callbacks(self):
input_ = InputCell(1)
output = ComputeCell([input_], lambda inputs: inputs[0] + 1)
observer = []
callback1 = self.callback_factory(observer)
output.add_callback(callback1)
input_.value = 3
self.assertEqual(observer[-1], 4)
def test_callbacks_only_fire_on_change(self):
input_ = InputCell(1)
output = ComputeCell(
[input_],
lambda inputs: 111 if inputs[0] < 3 else 222
)
observer = []
callback1 = self.callback_factory(observer)
output.add_callback(callback1)
input_.value = 2
self.assertEqual(observer, [])
input_.value = 4
self.assertEqual(observer[-1], 222)
def test_callbacks_do_not_report_already_reported_values(self):
input_ = InputCell(1)
output = ComputeCell([input_], lambda inputs: inputs[0] + 1)
observer = []
callback1 = self.callback_factory(observer)
output.add_callback(callback1)
input_.value = 2
self.assertEqual(observer[-1], 3)
input_.value = 3
self.assertEqual(observer[-1], 4)
def test_callbacks_can_fire_from_multiple_cells(self):
input_ = InputCell(1)
plus_one = ComputeCell([input_], lambda inputs: inputs[0] + 1)
minus_one = ComputeCell([input_], lambda inputs: inputs[0] - 1)
cb1_observer, cb2_observer = [], []
callback1 = self.callback_factory(cb1_observer)
callback2 = self.callback_factory(cb2_observer)
plus_one.add_callback(callback1)
minus_one.add_callback(callback2)
input_.value = 10
self.assertEqual(cb1_observer[-1], 11)
self.assertEqual(cb2_observer[-1], 9)
def test_callbacks_can_be_added_and_removed(self):
input_ = InputCell(11)
output = ComputeCell([input_], lambda inputs: inputs[0] + 1)
cb1_observer, cb2_observer, cb3_observer = [], [], []
callback1 = self.callback_factory(cb1_observer)
callback2 = self.callback_factory(cb2_observer)
callback3 = self.callback_factory(cb3_observer)
output.add_callback(callback1)
output.add_callback(callback2)
input_.value = 31
self.assertEqual(cb1_observer[-1], 32)
self.assertEqual(cb2_observer[-1], 32)
output.remove_callback(callback1)
output.add_callback(callback3)
input_.value = 41
self.assertEqual(cb2_observer[-1], 42)
self.assertEqual(cb3_observer[-1], 42)
# Expect callback1 not to be called.
self.assertEqual(len(cb1_observer), 1)
def test_removing_a_callback_multiple_times(self):
"""Guard against incorrect implementations which store their
callbacks in an array."""
input_ = InputCell(1)
output = ComputeCell([input_], lambda inputs: inputs[0] + 1)
cb1_observer, cb2_observer = [], []
callback1 = self.callback_factory(cb1_observer)
callback2 = self.callback_factory(cb2_observer)
output.add_callback(callback1)
output.add_callback(callback2)
output.remove_callback(callback1)
output.remove_callback(callback1)
output.remove_callback(callback1)
input_.value = 2
self.assertEqual(cb1_observer, [])
self.assertEqual(cb2_observer[-1], 3)
def test_callbacks_should_only_be_called_once(self):
"""Guard against incorrect implementations which call a callback
function multiple times when multiple dependencies change."""
input_ = InputCell(1)
plus_one = ComputeCell([input_], lambda inputs: inputs[0] + 1)
minus_one1 = ComputeCell([input_], lambda inputs: inputs[0] - 1)
minus_one2 = ComputeCell([minus_one1], lambda inputs: inputs[0] - 1)
output = ComputeCell(
[plus_one, minus_one2],
lambda inputs: inputs[0] * inputs[1]
)
observer = []
callback1 = self.callback_factory(observer)
output.add_callback(callback1)
input_.value = 4
self.assertEqual(observer[-1], 10)
def test_callbacks_not_called_so_long_as_output_not_changed(self):
"""Guard against incorrect implementations which call callbacks
if dependencies change but output value doesn't change."""
input_ = InputCell(1)
plus_one = ComputeCell([input_], lambda inputs: inputs[0] + 1)
minus_one = ComputeCell([input_], lambda inputs: inputs[0] - 1)
always_two = ComputeCell(
[plus_one, minus_one],
lambda inputs: inputs[0] - inputs[1]
)
observer = []
callback1 = self.callback_factory(observer)
always_two.add_callback(callback1)
input_.value = 2
input_.value = 3
input_.value = 4
input_.value = 5
self.assertEqual(observer, [])
# Utility functions.
def callback_factory(self, observer):
def callback(observer, value):
observer.append(value)
return partial(callback, observer)
if __name__ == '__main__':
unittest.main()