tests/Domain.Tests/OrderMoneyTests.cs

@@ -0,0 +1,46 @@
+namespace Domain.Tests;
+
+/// <summary>Unit tests for the <see cref="OrderMoney"/> value object.</summary>
+public class OrderMoneyTests
+{
+    [Fact]
+    public void From_keeps_the_cents()
+    {
+        Assert.Equal(150_00, OrderMoney.From(150_00).Cents);
+    }
+
+    [Fact]
+    public void Zero_is_valid()
+    {
+        Assert.Equal(0, OrderMoney.From(0).Cents);
+    }
+
+    [Fact]
+    public void Negative_cents_are_rejected()
+    {
+        Assert.Throws<ArgumentOutOfRangeException>(() => OrderMoney.From(-1));
+        Assert.Throws<ArgumentOutOfRangeException>(() => _ = (OrderMoney)(-1));   // conversion validates too
+    }
+
+    [Fact]
+    public void Money_compares_by_value_not_reference()
+    {
+        Assert.Equal(OrderMoney.From(150_00), OrderMoney.From(150_00));
+        Assert.NotEqual(OrderMoney.From(150_00), OrderMoney.From(151_00));
+    }
+
+    [Fact]
+    public void Converting_back_to_cents_is_explicit()
+    {
+        var money = OrderMoney.From(150_00);
+
+        Assert.Equal(150_00, (int)money);
+        Assert.Equal(150_00, money.Cents);
+    }
+
+    [Fact]
+    public void ToString_shows_the_cents()
+    {
+        Assert.Equal("15000", OrderMoney.From(150_00).ToString());
+    }
+}