Introduce unit testing on calculation objects

Tests/Calculation/DataProcessingTests.cs

@@ -1,19 +1,58 @@
 using Core.Calculation;
-using Tests.Parsers;
+using Core.Entities;
+using Tests.Builders;
+using Tests.Fixtures;
 
 namespace Tests.Calculation;
+
 [TestFixture]
 public class DataProcessingTests
 {
+	[SetUp]
+	public void SetUp()
+	{
+		BuilderExtensions.ResetAllBuilders();
+	}
 
 	[Test]
 	public void GetEventStudentRankingsTest()
 	{
-		var events = TestEntityHandler.GetEvents();
-		var students = TestEntityHandler.GetStudents(events);
-		var rankings = TestEntityHandler.GetStudentEventRankings(students, events);
+		// Create test data with explicit rankings
+		var flight = EventDefinitionBuilder.Individual("Flight").Build();
+		var coding = EventDefinitionBuilder.Individual("Coding").Build();
+		var robotics = EventDefinitionBuilder.Team("Robotics", 2, 5).Build();
 
-        foreach (var ranking in rankings)
+		var alice = StudentBuilder.Default()
+			.WithName("Alice", "Anderson")
+			.WithGrade(9)
+			.WithRanking(flight, rank: 1)
+			.WithRanking(coding, rank: 2)
+			.WithRanking(robotics, rank: 3)
+			.Build();
+
+		var bob = StudentBuilder.Default()
+			.WithName("Bob", "Brown")
+			.WithGrade(10)
+			.WithRanking(coding, rank: 1)
+			.WithRanking(flight, rank: 3)
+			.Build();
+
+		// Verify rankings are accessible
+		Assert.That(alice.EventRankings, Has.Count.EqualTo(3));
+		Assert.That(bob.EventRankings, Has.Count.EqualTo(2));
+
+		// Verify rankings are correctly associated
+		var aliceFlightRanking = alice.EventRankings.First(r => r.EventDefinition == flight);
+		Assert.That(aliceFlightRanking.Rank, Is.EqualTo(1));
+		Assert.That(aliceFlightRanking.Student, Is.EqualTo(alice));
+
+		// Print rankings for verification (matching original test output)
+		var allRankings = new[] { alice, bob }
+			.SelectMany(s => s.EventRankings)
+			.OrderBy(r => r.EventDefinition.Name)
+			.ThenBy(r => r.Student.FirstName);
+
+		foreach (var ranking in allRankings)
 		{
 			Console.WriteLine(ranking.EventDefinition.Name);
 			Console.WriteLine($"{ranking.Student.FirstName}: {ranking.Rank}");