Add unittests

src/backend/tests/unit/Users/UserStateTests.cs

@@ -0,0 +1,42 @@
+using Randall.Domain.Users;
+
+namespace Randall.Domain.UnitTests.Users;
+
+public class UserStateTests
+{
+    private static User CreateRegularUser() =>
+        User.Create("jane@company.com", "Jane Smith", "hash").Value!;
+
+    [Fact]
+    public void Approve_SetsIsApprovedToTrue()
+    {
+        var user = CreateRegularUser();
+
+        user.Approve();
+
+        Assert.True(user.IsApproved);
+    }
+
+    [Fact]
+    public void MakeAdmin_SetsIsAdminAndIsApproved()
+    {
+        var user = CreateRegularUser();
+
+        user.MakeAdmin();
+
+        Assert.True(user.IsAdmin);
+        Assert.True(user.IsApproved);
+    }
+
+    [Fact]
+    public void MakeAdmin_OnAlreadyApprovedUser_RemainsApproved()
+    {
+        var user = CreateRegularUser();
+        user.Approve();
+
+        user.MakeAdmin();
+
+        Assert.True(user.IsApproved);
+        Assert.True(user.IsAdmin);
+    }
+}