exercism/elixir/paint-by-number/test/paint_by_number_test.exs

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2023-12-19 14:38:41 +00:00
defmodule PaintByNumberTest do
use ExUnit.Case
describe "palette_bit_size/1" do
@tag task_id: 1
test "needs 1 bit to encode two colors" do
color_count = 2
assert PaintByNumber.palette_bit_size(color_count) == 1
end
@tag task_id: 1
test "needs 2 bits to encode three colors" do
color_count = 3
assert PaintByNumber.palette_bit_size(color_count) == 2
end
@tag task_id: 1
test "needs 2 bits to encode four colors" do
color_count = 4
assert PaintByNumber.palette_bit_size(color_count) == 2
end
@tag task_id: 1
test "needs 3 bits to encode seven colors" do
color_count = 7
assert PaintByNumber.palette_bit_size(color_count) == 3
end
@tag task_id: 1
test "needs 3 bits to encode eight colors" do
color_count = 8
assert PaintByNumber.palette_bit_size(color_count) == 3
end
@tag task_id: 1
test "needs 4 bits to encode nine colors" do
color_count = 9
assert PaintByNumber.palette_bit_size(color_count) == 4
end
@tag task_id: 1
test "needs 4 bits to encode fourteen colors" do
color_count = 14
assert PaintByNumber.palette_bit_size(color_count) == 4
end
@tag task_id: 1
test "needs 6 bits to encode fifty colors" do
color_count = 50
assert PaintByNumber.palette_bit_size(color_count) == 6
end
@tag task_id: 1
test "needs 20 bits to encode 1 million colors" do
color_count = 1_000_000
assert PaintByNumber.palette_bit_size(color_count) == 20
end
end
describe "empty_picture/0" do
@tag task_id: 2
test "returns an empty bitstring" do
assert PaintByNumber.empty_picture() == <<>>
end
end
describe "test_picture/0" do
@tag task_id: 3
test "returns the numbers 0, 1, 2, and 3 as fragments of size 2" do
assert PaintByNumber.test_picture() == <<0::2, 1::2, 2::2, 3::2>>
end
end
describe "prepend_pixel/3" do
@tag task_id: 4
test "works with an empty picture" do
picture = <<>>
color_count = 16
pixel_color_index = 1
assert PaintByNumber.prepend_pixel(picture, color_count, pixel_color_index) == <<1::4>>
end
@tag task_id: 4
test "works with a non-empty picture" do
picture = <<3::3, 2::3, 2::3>>
color_count = 7
pixel_color_index = 0
assert PaintByNumber.prepend_pixel(picture, color_count, pixel_color_index) ==
<<0::3, 3::3, 2::3, 2::3>>
end
@tag task_id: 4
test "pixel color overflows if it doesn't fit in palette size" do
picture = <<3::6>>
color_count = 64
pixel_color_index = 64
assert PaintByNumber.prepend_pixel(picture, color_count, pixel_color_index) ==
<<0::6, 3::6>>
end
end
describe "get_first_pixel/2" do
@tag task_id: 5
test "returns nil if empty picture" do
picture = <<>>
color_count = 16
assert PaintByNumber.get_first_pixel(picture, color_count) == nil
end
@tag task_id: 5
test "works with a non-empty picture" do
picture = <<1::2, 0::2, 0::2, 2::2>>
color_count = 3
assert PaintByNumber.get_first_pixel(picture, color_count) == 1
end
@tag task_id: 5
test "can reinterpret picture data with a different color count" do
picture = <<0b01::2, 0b10::2, 0b00::2, 0b10::2>>
# Color count of 8 means 3 bits.
color_count = 8
# We take bits from segments until we have 3 bits.
# First, we take `01` from the first segment. Then, `1` from the second segment.
# This gives us the binary number `011`, which is equal to the decimal number 5.
assert PaintByNumber.get_first_pixel(picture, color_count) == 0b011
end
end
describe "drop_first_pixel/2" do
@tag task_id: 6
test "returns empty picture if empty picture" do
picture = <<>>
color_count = 5
assert PaintByNumber.drop_first_pixel(picture, color_count) == <<>>
end
@tag task_id: 6
test "works with a non-empty picture" do
picture = <<23::5, 21::5, 15::5, 3::5>>
color_count = 32
assert PaintByNumber.drop_first_pixel(picture, color_count) == <<21::5, 15::5, 3::5>>
end
@tag task_id: 6
test "can reinterpret picture data with a different color count" do
picture = <<0b011011::6, 0b110001::6>>
# Color count of 4 means 2 bits.
color_count = 4
# We remove the first 2 bits from the first segment.
assert PaintByNumber.drop_first_pixel(picture, color_count) == <<0b1011::4, 0b110001::6>>
end
end
describe "concat_pictures/2" do
@tag task_id: 7
test "two empty pictures result in an empty picture" do
picture1 = <<>>
picture2 = <<>>
assert PaintByNumber.concat_pictures(picture1, picture2) == <<>>
end
@tag task_id: 7
test "a non-picture with an empty picture" do
picture1 = <<5::3, 2::3, 2::3, 4::3>>
picture2 = <<>>
assert PaintByNumber.concat_pictures(picture1, picture2) == picture1
end
@tag task_id: 7
test "an empty picture with a non-empty picture" do
picture1 = <<>>
picture2 = <<13::4, 11::4, 0::4>>
assert PaintByNumber.concat_pictures(picture1, picture2) == picture2
end
@tag task_id: 7
test "two non-empty pictures" do
picture1 = <<2::4, 2::4, 1::4, 14::4>>
picture2 = <<15::4, 14::4>>
assert PaintByNumber.concat_pictures(picture1, picture2) ==
<<2::4, 2::4, 1::4, 14::4, 15::4, 14::4>>
end
@tag task_id: 7
test "two non-empty pictures with different palette bit sizes" do
picture1 = <<0b00::2, 0b01::2, 0b11::2, 0b01::2>>
picture2 = <<0b10101::5, 0b10011::5>>
assert PaintByNumber.concat_pictures(picture1, picture2) ==
<<0b00011101::8, 0b10101100::8, 0b11::2>>
end
end
end