57 lines
1.5 KiB
C#
57 lines
1.5 KiB
C#
using Xunit;
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namespace Prices.Tests;
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public sealed class PriceCalculatorTests
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{
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[Fact]
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public void No_discount_keeps_the_price()
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{
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Assert.Equal(100m, PriceCalculator.ApplyDiscount(100m, 0m));
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}
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[Fact]
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public void A_full_discount_makes_it_free()
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{
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Assert.Equal(0m, PriceCalculator.ApplyDiscount(200m, 100m));
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}
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[Fact]
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public void A_quarter_off_200_is_150()
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{
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Assert.Equal(150m, PriceCalculator.ApplyDiscount(200m, 25m));
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}
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[Fact]
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public void Half_off_80_is_40()
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{
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Assert.Equal(40m, PriceCalculator.ApplyDiscount(80m, 50m));
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}
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[Fact]
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public void A_discount_above_100_percent_is_refused()
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{
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Assert.Throws<ArgumentOutOfRangeException>(() => PriceCalculator.ApplyDiscount(100m, 101m));
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}
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[Fact]
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public void Swiss_rappernrundung_rounds_to_nearest_0_05()
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{
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// 99.90 * 0.9 = 89.91 → 89.91 * 20 = 1798.2 → round to 1798 → 1798 / 20 = 89.90
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Assert.Equal(89.90m, PriceCalculator.ApplyDiscount(99.90m, 10m));
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}
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[Fact]
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public void Rounding_rounds_down_when_cent_remainder_is_below_0_05()
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{
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// 1.23 * 0.5 = 0.615 → 0.615 * 20 = 12.3 → round to 12 → 12 / 20 = 0.60
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Assert.Equal(0.60m, PriceCalculator.ApplyDiscount(1.23m, 50m));
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}
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[Fact]
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public void Rounding_rounds_up_when_cent_remainder_is_at_0_05()
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{
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// 3.37 * 0.5 = 1.685 → 1.685 * 20 = 33.7 → round to 34 → 34 / 20 = 1.70
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Assert.Equal(1.70m, PriceCalculator.ApplyDiscount(3.37m, 50m));
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}
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} |