Everything done, but cannot run unit tests

Pupils/Pupil.cs

@@ -0,0 +1,169 @@
+using System.Security.Principal;
+
+namespace Pupils;
+
+public class Pupil
+{
+    private static int _nextId;
+    private readonly DateOnly _dateOfBirth;
+    private int? _zipCode;
+    private readonly string Name;
+
+    /// <summary>
+    /// Gets the age of the pupil.
+    /// </summary>
+    public int Age
+    {
+        get
+        {
+            var today = DateOnly.FromDateTime(DateTime.Today);
+            var age = today.Year - _dateOfBirth.Year;
+            if (today < _dateOfBirth.AddYears(age))
+            {
+                age--;
+            }
+            return age;
+        }
+    }
+
+    /// <summary>
+    /// Gets or sets the ZIP code of the pupil.
+    /// </summary>
+    /// <remarks>
+    /// The ZIP code must be between 1000 and 9999 inclusive.
+    /// </remarks>
+    public int? ZipCode
+    {
+        get
+        {
+            return _zipCode;
+        }
+
+        set
+        {
+            if (value >= 1000 && value <= 9999)
+            {
+                _zipCode = value;
+            }
+        }
+    }
+
+    /// <summary>
+    /// Gets the first name of the pupil.
+    /// </summary>
+    public string FirstName
+    {
+        get
+        {
+            string firstName = "";
+            for (int i = 0; i < Name.Length; i++)
+            {
+                if (!String.IsNullOrWhiteSpace(char.ToString(Name[i])))
+                {
+                    firstName += Name[i];
+                }
+                else
+                {
+                    return firstName;
+                }
+            }
+            return firstName;
+        }
+    }
+
+    /// <summary>
+    /// Gets the last name of the pupil.
+    /// </summary>
+    public string LastName
+    {
+        get
+        {
+            string lastName = "";
+            for (int i = Name.Length - 1; i > 0; i--)
+            {
+                if (!String.IsNullOrWhiteSpace(char.ToString(Name[i])))
+                {
+                    lastName = Name[i] + lastName;
+                }
+                else
+                {
+                    return lastName;
+                }
+            }
+            return lastName;
+        }
+    }
+
+    /// <summary>
+    /// Gets the unique ID of the pupil.
+    /// </summary>
+    public int Id { get; }
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="Pupil"/> class.
+    /// </summary>
+    /// <param name="firstName">The first name of the pupil.</param>
+    /// <param name="lastName">The last name of the pupil.</param>
+    /// <param name="dateOfBirth">The date of birth of the pupil.</param>
+    public Pupil(string firstName, string lastName, DateOnly dateOfBirth)
+    {
+        Id = ++_nextId;
+        Name = $"{firstName} {lastName}";
+        _dateOfBirth = dateOfBirth;
+    }
+
+    /// <summary>
+    /// Determines whether the pupil is of a specified age type.
+    /// </summary>
+    /// <param name="ageType">The age type to check.</param>
+    /// <returns><c>true</c> if the pupil is of the specified age type; otherwise, <c>false</c>.</returns>
+    public bool IsOfAge(AgeType ageType)
+    {
+        int requiredAge;
+
+        switch (ageType)
+        {
+            case AgeType.VotingAge:
+                requiredAge = 16;
+                break;
+            case AgeType.FullAge:
+                requiredAge = 18;
+                break;
+            case AgeType.RetirementAge:
+                requiredAge = 65;
+                break;
+            default:
+                return false;
+        }
+
+        return Age >= requiredAge;
+    }
+
+    /// <summary>
+    /// Determines whether the current pupil is older than another pupil.
+    /// </summary>
+    /// <param name="other">The other pupil to compare with.</param>
+    /// <returns><c>true</c> if the current pupil is older than the other pupil; otherwise, <c>false</c>.</returns>
+    public bool IsOlderThan(Pupil other)
+    {
+        return Age > other.Age;
+    }
+
+    /// <summary>
+    /// Determines whether the current pupil lives nearby another pupil.
+    /// </summary>
+    /// <param name="other">The other pupil to compare with.</param>
+    /// <returns><c>true</c> if the first two digits of the ZIP codes match; otherwise, <c>false</c>.</returns>
+    public bool LivesNearby(Pupil other)
+    {
+        if (ZipCode == null || other.ZipCode == null)
+        {
+            return false;
+        }
+
+        string thisZipPrefix = ZipCode.Value.ToString().Substring(0, 2);
+        string otherZipPrefix = other.ZipCode.Value.ToString().Substring(0, 2);
+
+        return thisZipPrefix == otherZipPrefix;
+    }
+}

Pupils/PupilTests.cs

@@ -0,0 +1,61 @@
+using Xunit;
+
+namespace Pupils.Tests
+{
+    public class PupilTests
+    {
+        [Fact]
+        public void IsOlderThan_ReturnsTrue_WhenCurrentPupilIsOlder()
+        {
+            var pupil1 = new Pupil("John", "Doe", new DateOnly(2000, 1, 1));
+            var pupil2 = new Pupil("Jane", "Smith", new DateOnly(2005, 1, 1));
+
+            Assert.True(pupil1.IsOlderThan(pupil2));
+        }
+
+        [Fact]
+        public void IsOlderThan_ReturnsFalse_WhenCurrentPupilIsYounger()
+        {
+            var pupil1 = new Pupil("John", "Doe", new DateOnly(2005, 1, 1));
+            var pupil2 = new Pupil("Jane", "Smith", new DateOnly(2000, 1, 1));
+
+            Assert.False(pupil1.IsOlderThan(pupil2));
+        }
+
+        [Fact]
+        public void LivesNearby_ReturnsTrue_WhenZipCodesMatch()
+        {
+            var pupil1 = new Pupil("John", "Doe", new DateOnly(2000, 1, 1)) { ZipCode = 4060 };
+            var pupil2 = new Pupil("Jane", "Smith", new DateOnly(2005, 1, 1)) { ZipCode = 4030 };
+
+            Assert.True(pupil1.LivesNearby(pupil2));
+        }
+
+        [Fact]
+        public void LivesNearby_ReturnsFalse_WhenZipCodesDoNotMatch()
+        {
+            var pupil1 = new Pupil("John", "Doe", new DateOnly(2000, 1, 1)) { ZipCode = 4060 };
+            var pupil2 = new Pupil("Jane", "Smith", new DateOnly(2005, 1, 1)) { ZipCode = 1010 };
+
+            Assert.False(pupil1.LivesNearby(pupil2));
+        }
+
+        [Fact]
+        public void LivesNearby_ReturnsFalse_WhenEitherZipCodeIsNull()
+        {
+            var pupil1 = new Pupil("John", "Doe", new DateOnly(2000, 1, 1)) { ZipCode = null };
+            var pupil2 = new Pupil("Jane", "Smith", new DateOnly(2005, 1, 1)) { ZipCode = 4030 };
+
+            Assert.False(pupil1.LivesNearby(pupil2));
+        }
+
+        [Fact]
+        public void Id_IsUniqueForEachPupil()
+        {
+            var pupil1 = new Pupil("John", "Doe", new DateOnly(2000, 1, 1));
+            var pupil2 = new Pupil("Jane", "Smith", new DateOnly(2005, 1, 1));
+
+            Assert.NotEqual(pupil1.Id, pupil2.Id);
+        }
+    }
+}

Pupils/Pupils.csproj

@@ -8,4 +8,8 @@
 		<TreatWarningsAsErrors>true</TreatWarningsAsErrors>
 	</PropertyGroup>
 
+	<ItemGroup>
+	  <PackageReference Include="xunit" Version="2.9.2" />
+	</ItemGroup>
+
 </Project>