Apply nullability

AdventOfCode.Common/AdventOfCode.Common.csproj

@@ -3,8 +3,8 @@
     <PropertyGroup>
         <TargetFramework>net8.0</TargetFramework>
         <ImplicitUsings>enable</ImplicitUsings>
-        <RootNamespace>AdventOfCode.Common</RootNamespace>
         <Nullable>enable</Nullable>
+        <RootNamespace>AdventOfCode.Common</RootNamespace>
     </PropertyGroup>
 
 </Project>

AdventOfCode2017.Tests/AdventOfCode2017.Tests.csproj

@@ -3,9 +3,11 @@
     <PropertyGroup>
         <TargetFramework>net8.0</TargetFramework>
         <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
         <RootNamespace>AdventOfCode2017.Tests</RootNamespace>
 
         <IsPackable>false</IsPackable>
+        <IsTestProject>true</IsTestProject>
     </PropertyGroup>
 
     <ItemGroup>

AdventOfCode2017/AdventOfCode2017.csproj

@@ -4,6 +4,7 @@
         <OutputType>Exe</OutputType>
         <TargetFramework>net8.0</TargetFramework>
         <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
         <RootNamespace>AdventOfCode2017</RootNamespace>
     </PropertyGroup>
 

AdventOfCode2017/Day03.cs

@@ -30,11 +30,11 @@ public class Day03 : IDay
 {
     public string ResolvePart1(string[] inputs)
     {
-        return null;
+        return string.Empty;
     }
 
     public string ResolvePart2(string[] inputs)
     {
-        return null;
+        return string.Empty;
     }
 }

AdventOfCode2018.Tests/AdventOfCode2018.Tests.csproj

@@ -3,9 +3,11 @@
     <PropertyGroup>
         <TargetFramework>net8.0</TargetFramework>
         <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
         <RootNamespace>AdventOfCode2018.Tests</RootNamespace>
 
         <IsPackable>false</IsPackable>
+        <IsTestProject>true</IsTestProject>
     </PropertyGroup>
 
     <ItemGroup>

AdventOfCode2018.Tests/Day06_Tests.cs

@@ -7,28 +7,28 @@ public class Day06_Tests
     [Fact]
     public void ChronoPoint_FromString__Test1()
     {
-        Day06.ChronoPoint point = Day06.ChronoPoint.FromString("1, 1");
+        Day06.ChronoPoint? point = Day06.ChronoPoint.FromString("1, 1");
 
-        Assert.Equal(1, point.X);
+        Assert.Equal(1, point?.X);
-        Assert.Equal(1, point.Y);
+        Assert.Equal(1, point?.Y);
     }
 
     [Fact]
     public void ChronoPoint_FromString__Test2()
     {
-        Day06.ChronoPoint point = Day06.ChronoPoint.FromString("1, 6");
+        Day06.ChronoPoint? point = Day06.ChronoPoint.FromString("1, 6");
 
-        Assert.Equal(1, point.X);
+        Assert.Equal(1, point?.X);
-        Assert.Equal(6, point.Y);
+        Assert.Equal(6, point?.Y);
     }
 
     [Fact]
     public void ChronoPoint_FromString__Test3()
     {
-        Day06.ChronoPoint point = Day06.ChronoPoint.FromString("8, 9");
+        Day06.ChronoPoint? point = Day06.ChronoPoint.FromString("8, 9");
 
-        Assert.Equal(8, point.X);
+        Assert.Equal(8, point?.X);
-        Assert.Equal(9, point.Y);
+        Assert.Equal(9, point?.Y);
     }
 
     #endregion ChronoPoint_FromString
@@ -38,9 +38,12 @@ public class Day06_Tests
     [Fact]
     public void ChronoPoint_ManhattanDistance__Test1()
     {
-        Day06.ChronoPoint p0 = Day06.ChronoPoint.FromString("8, 9");
+        Day06.ChronoPoint? p0 = Day06.ChronoPoint.FromString("8, 9");
-        Day06.ChronoPoint p1 = Day06.ChronoPoint.FromString("1, 6");
+        Day06.ChronoPoint? p1 = Day06.ChronoPoint.FromString("1, 6");
 
+        Assert.NotNull(p0);
+        Assert.NotNull(p1);
+        
         int distance = Day06.ChronoPoint.ManhattanDistance(p0, p1);
 
         Assert.Equal(10, distance);
@@ -49,9 +52,12 @@ public class Day06_Tests
     [Fact]
     public void ChronoPoint_ManhattanDistance__Test2()
     {
-        Day06.ChronoPoint p0 = Day06.ChronoPoint.FromString("1, 1");
+        Day06.ChronoPoint? p0 = Day06.ChronoPoint.FromString("1, 1");
-        Day06.ChronoPoint p1 = Day06.ChronoPoint.FromString("1, 6");
+        Day06.ChronoPoint? p1 = Day06.ChronoPoint.FromString("1, 6");
 
+        Assert.NotNull(p0);
+        Assert.NotNull(p1);
+        
         int distance = Day06.ChronoPoint.ManhattanDistance(p0, p1);
 
         Assert.Equal(5, distance);

AdventOfCode2018/AdventOfCode2018.csproj

@@ -4,6 +4,7 @@
         <OutputType>Exe</OutputType>
         <TargetFramework>net8.0</TargetFramework>
         <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
         <RootNamespace>AdventOfCode2018</RootNamespace>
     </PropertyGroup>
 

AdventOfCode2018/Day01.cs

@@ -82,7 +82,7 @@ public class Day01 : IDay
     public string ResolvePart2(string[] inputs)
     {
         int accumulator = 0;
-        List<int> accumulatorHistory = new();
+        List<int> accumulatorHistory = [];
         int? repeatedAccumulator = null;
         while (repeatedAccumulator == null)
         {
@@ -108,6 +108,6 @@ public class Day01 : IDay
                 }
             }
         }
-        return repeatedAccumulator.ToString();
+        return repeatedAccumulator.ToString() ?? string.Empty;
     }
 }

AdventOfCode2018/Day03.cs

@@ -94,7 +94,7 @@ public class Day03 : IDay
     {
         List<Claim> claims = inputs.Select(Claim.FromString).ToList();
 
-        Claim unOverlappingClaim = null;
+        Claim? unOverlappingClaim = null;
         for (int i = 0; i < claims.Count; i++)
         {
             bool overlaps = false;
@@ -113,7 +113,7 @@ public class Day03 : IDay
                 break;
             }
         }
-        return unOverlappingClaim.ID.ToString();
+        return unOverlappingClaim?.ID.ToString() ?? string.Empty;
 
     }
 

AdventOfCode2018/Day04.cs

@@ -71,7 +71,7 @@ public class Day04 : IDay
         Dictionary<int, GuardSleepHistogram> dictFullHistogram = BuildFullHistogram(guardEvents);
 
         // Find sleepier guard
-        GuardSleepHistogram highestSleeperHistogram = null;
+        GuardSleepHistogram? highestSleeperHistogram = null;
         long highestTotalSleep = long.MinValue;
         foreach (GuardSleepHistogram guardHistogram in dictFullHistogram.Values)
         {
@@ -83,6 +83,7 @@ public class Day04 : IDay
                 highestTotalSleep = totalSleep;
             }
         }
+        if (highestSleeperHistogram == null) { return string.Empty; }
 
         // Find sleepier minute
         int maxSleepMinute = int.MinValue;
@@ -156,14 +157,12 @@ public class Day04 : IDay
 
             foreach (GuardSleepHistogram dayGuardHistogram in dictDayHistogram.Values)
             {
-                if (dictFullHistogram.TryGetValue(dayGuardHistogram.ID, out GuardSleepHistogram guardHistogram))
+                if (dictFullHistogram.TryGetValue(dayGuardHistogram.ID, out GuardSleepHistogram? guardHistogram))
                 {
                     guardHistogram.AddHistogram(dayGuardHistogram);
+                    continue;
                 }
-                else
+                dictFullHistogram.Add(dayGuardHistogram.ID, dayGuardHistogram);
-                {
-                    dictFullHistogram.Add(dayGuardHistogram.ID, dayGuardHistogram);
-                }
             }
         }
 

AdventOfCode2018/Day06.cs

@@ -97,6 +97,7 @@ public class Day06 : IDay
         return inputs
             .Where(input => string.IsNullOrEmpty(input) == false)
             .Select(ChronoPoint.FromString)
+            .OfType<ChronoPoint>()
             .ToList();
     }
 
@@ -197,7 +198,7 @@ public class Day06 : IDay
         public int X { get; set; }
         public int Y { get; set; }
 
-        public static ChronoPoint FromString(string strPoint)
+        public static ChronoPoint? FromString(string strPoint)
         {
             if (string.IsNullOrEmpty(strPoint)) { return null; }
             string[] parts = strPoint.Split([", "], StringSplitOptions.RemoveEmptyEntries);

AdventOfCode2018/Day07.cs

@@ -128,9 +128,9 @@ public class Day07 : IDay
         return totalElapsedTime.ToString();
     }
 
-    public class InstructionNode
+    public class InstructionNode(string nodeID)
     {
-        public string NodeID { get; init; }
+        public string NodeID { get; init; } = nodeID;
 
         public List<string> PreviousNodeIDs { get; } = [];
 
@@ -154,16 +154,12 @@ public class Day07 : IDay
 
         private InstructionNode GetNode(string nodeID)
         {
-            InstructionNode node;
+            if (Nodes.TryGetValue(nodeID, out InstructionNode? nodeAux))
-            if (Nodes.TryGetValue(nodeID, out InstructionNode nodeAux))
             {
-                node = nodeAux;
+                return nodeAux;
-            }
-            else
-            {
-                node = new InstructionNode { NodeID = nodeID, };
-                Nodes.Add(nodeID, node);
             }
+            InstructionNode node = new(nodeID);
+            Nodes.Add(nodeID, node);
             return node;
         }
 
@@ -194,7 +190,8 @@ public class Day07 : IDay
                     .ToList();
                 if (unusedNodes.Count > 0)
                 {
-                    InstructionNode node = unusedNodes.FirstOrDefault();
+                    InstructionNode? node = unusedNodes.FirstOrDefault();
+                    if (node == null) { continue; }
                     finalNodes.Add(node);
                     node.Used = true;
                 }
@@ -204,7 +201,7 @@ public class Day07 : IDay
 
         private class SimulatedWorker
         {
-            public InstructionNode CurrentInstruction { get; private set; }
+            public InstructionNode? CurrentInstruction { get; private set; }
             private int ElapsedTime { get; set; }
 
             public void SetInstruction(InstructionNode instruction)

AdventOfCode2018/Day09.cs

@@ -87,16 +87,16 @@ public class Day09 : IDay
     public class Marble
     {
         public long Value { get; init; }
-        public Marble Previous { get; set; }
+        public Marble? Previous { get; set; }
-        public Marble Next { get; set; }
+        public Marble? Next { get; set; }
     }
 
     public class MarbleGame
     {
         private Dictionary<long, long> Scores { get; } = new();
 
-        private Marble _firstMarble;
+        private Marble? _firstMarble;
-        private Marble _currentMarble;
+        private Marble? _currentMarble;
         private long _currentPlayer;
 
         private const long PointValueMultiple = 23;
@@ -119,20 +119,34 @@ public class Day09 : IDay
                 Marble newMarble = new() { Value = i + 1 };
                 if ((newMarble.Value % PointValueMultiple) > 0)
                 {
-                    Marble previousMarble = _currentMarble.Next;
+                    Marble? previousMarble = _currentMarble?.Next;
-                    Marble nextMarble = previousMarble.Next;
+                    Marble? nextMarble = previousMarble?.Next;
                     newMarble.Previous = previousMarble;
                     newMarble.Next = nextMarble;
-                    previousMarble.Next = newMarble;
+                    if(previousMarble != null)
-                    nextMarble.Previous = newMarble;
+                    {
+                        previousMarble.Next = newMarble;
+                    }
+                    if(nextMarble != null)
+                    {
+                        nextMarble.Previous = newMarble;
+                    }
                     _currentMarble = newMarble;
                 }
                 else
                 {
-                    Marble marbleToRemove = _currentMarble.Previous.Previous.Previous.Previous.Previous.Previous.Previous;
+                    Marble? marbleToRemove = _currentMarble?.Previous?.Previous?.Previous?.Previous?.Previous?.Previous?.Previous;
-                    _currentMarble = marbleToRemove.Next;
+                    _currentMarble = marbleToRemove?.Next;
-                    marbleToRemove.Previous.Next = marbleToRemove.Next;
+                    if (marbleToRemove == null) { continue; }
-                    marbleToRemove.Next.Previous = marbleToRemove.Previous;
+                    
+                    if(marbleToRemove.Previous != null)
+                    {
+                        marbleToRemove.Previous.Next = marbleToRemove.Next;
+                    }
+                    if (marbleToRemove.Next != null)
+                    {
+                        marbleToRemove.Next.Previous = marbleToRemove.Previous;
+                    }
 
                     long currentPlayerScore = Scores[_currentPlayer] + (newMarble.Value + marbleToRemove.Value);
                     Scores[_currentPlayer] = currentPlayerScore;
@@ -144,14 +158,14 @@ public class Day09 : IDay
         private void PrintStatus()
         {
             Console.Write("[{0}] ", _currentPlayer);
-            Marble marble = _firstMarble;
+            Marble? marble = _firstMarble;
             do
             {
-                Console.Write(_currentMarble.Value == marble.Value 
+                Console.Write(_currentMarble?.Value == marble?.Value 
                     ? "({0}) " 
-                    : "{0} ", marble.Value);
+                    : "{0} ", marble?.Value);
-                marble = marble.Next;
+                marble = marble?.Next;
-            } while (marble.Value != 0);
+            } while (marble != null && marble.Value != 0);
             Console.WriteLine();
         }
 

AdventOfCode2018/Day12.cs

@@ -111,8 +111,8 @@ public class Day12 : IDay
     private readonly List<bool> _initialState = [];
     private readonly List<PlantRule> _rules = [];
     private long _offsetField;
-    private bool[] _field;
+    private bool[] _field = [];
-    private bool[] _workField;
+    private bool[] _workField = [];
 
     private void Initialize(string[] inputs)
     {

AdventOfCode2018/Day13.cs

@@ -217,7 +217,7 @@ public class Day13 : IDay
     public string ResolvePart1(string[] inputs)
     {
         Initialize(inputs);
-        Train collidingTrain;
+        Train? collidingTrain;
         do
         {
             if (ShowProgress) { ShowGrid(); }
@@ -229,7 +229,7 @@ public class Day13 : IDay
     public string ResolvePart2(string[] inputs)
     {
         Initialize(inputs);
-        Train lastCart;
+        Train? lastCart;
         do
         {
             if (ShowProgress) { ShowGrid(); }
@@ -371,7 +371,7 @@ public class Day13 : IDay
 
     private int _width;
     private int _height;
-    private char[,] _grid;
+    private char[,] _grid = new char[0, 0];
     private readonly List<Train> _trains = [];
 
     private void Initialize(string[] inputs)
@@ -430,9 +430,9 @@ public class Day13 : IDay
         }
     }
 
-    private Train SimulateForFirstCollision()
+    private Train? SimulateForFirstCollision()
     {
-        Train collidingTrain = null;
+        Train? collidingTrain = null;
         IEnumerable<Train> orderedTrains = _trains.OrderBy(t => t.X + (t.Y * _width));
         foreach (Train t in orderedTrains)
         {
@@ -443,13 +443,13 @@ public class Day13 : IDay
         return collidingTrain;
     }
 
-    private Train SimulateForLastCart()
+    private Train? SimulateForLastCart()
     {
         List<Train> orderedTrains = _trains.OrderBy(t => t.X + (t.Y * _width)).ToList();
         foreach (Train t in orderedTrains)
         {
             t.Simulate(_grid);
-            Train collidingTrain = _trains.FirstOrDefault(x => x.X == t.X && x.Y == t.Y && t != x);
+            Train? collidingTrain = _trains.FirstOrDefault(x => x.X == t.X && x.Y == t.Y && t != x);
             if (collidingTrain != null)
             {
                 _trains.Remove(t);
@@ -470,7 +470,7 @@ public class Day13 : IDay
         {
             for (int i = 0; i < _width; i++)
             {
-                Train t = _trains.FirstOrDefault(x => x.X == i && x.Y == j);
+                Train? t = _trains.FirstOrDefault(x => x.X == i && x.Y == j);
                 if (t != null)
                 {
                     if (t.Direction == TrainDirection.North)

AdventOfCode2018/Day14.cs

@@ -62,7 +62,7 @@ public class Day14 : IDay
 {
     private long _numRecipes;
     private long _numRecipesAllocated;
-    private byte[] _recipes;
+    private byte[] _recipes = [];
     private long _idxA;
     private long _idxB;
     private long _searchSkip;

AdventOfCode2018/Day15.cs

@@ -444,9 +444,9 @@ public class Day15 : IDay
 
     private int _width;
     private int _height;
-    private char[,] _map;
+    private char[,] _map = new char[0, 0];
-    private List<Entity> _entities;
+    private readonly List<Entity> _entities = [];
-    private BreadthFirstSearchGrid _search;
+    private BreadthFirstSearchGrid? _search;
     private int _rounds;
 
     private void Init(string[] inputs)
@@ -454,7 +454,7 @@ public class Day15 : IDay
         _height = inputs.Length;
         _width = inputs.Max(input => input.Length);
         _map = new char[_width, _height];
-        _entities = new List<Entity>();
+        _entities.Clear();
         for (int j = 0; j < _height; j++)
         {
             for (int i = 0; i < _width; i++)
@@ -509,7 +509,7 @@ public class Day15 : IDay
             .ThenBy(e => e.X);
     }
 
-    private Entity GetBestInRangeTarget(Entity entity, IEnumerable<Entity> targets)
+    private Entity? GetBestInRangeTarget(Entity entity, IEnumerable<Entity> targets)
     {
         return targets
             .Where(entity.InRangeOf)
@@ -521,6 +521,7 @@ public class Day15 : IDay
 
     private void AddTarget(List<Target> targets, int targetX, int targetY, int priority)
     {
+        if (_search == null) { return;}
         if (targetX >= 0 && targetX < _width && targetY >= 0 && targetY < _height && _map[targetX, targetY] == '.')
         {
             int distance = _search.QueryDistance(targetX, targetY);
@@ -538,6 +539,7 @@ public class Day15 : IDay
 
     private void RunBattle()
     {
+        if (_search == null) { return;}
         _rounds = 0;
         bool running = true;
         do
@@ -554,7 +556,7 @@ public class Day15 : IDay
                 }
 
                 // Attack
-                Entity targetInRange = GetBestInRangeTarget(entity, entitiesTargets);
+                Entity? targetInRange = GetBestInRangeTarget(entity, entitiesTargets);
                 if (targetInRange != null)
                 {
                     entity.Attack(_map, targetInRange);
@@ -572,7 +574,7 @@ public class Day15 : IDay
                     AddTarget(targets, entityTarget.X + 1, entityTarget.Y, priority++);
                     AddTarget(targets, entityTarget.X, entityTarget.Y + 1, priority++);
                 }
-                Target bestTarget = targets.OrderBy(t => t.Distance).ThenBy(t => t.Priority).FirstOrDefault();
+                Target? bestTarget = targets.OrderBy(t => t.Distance).ThenBy(t => t.Priority).FirstOrDefault();
                 if (bestTarget != null)
                 {
                     _search.SearchCharGrid(_map, '.', bestTarget.X, bestTarget.Y);
@@ -594,7 +596,7 @@ public class Day15 : IDay
                     dirTarget.Distance = _search.QueryDistance(dirTarget.X, dirTarget.Y);
                     if (dirTarget.Distance >= 0) targets.Add(dirTarget);
 
-                    Target finalTarget = targets
+                    Target? finalTarget = targets
                         .OrderBy(t => t.Distance)
                         .ThenBy(t => t.Priority)
                         .FirstOrDefault();
@@ -606,7 +608,7 @@ public class Day15 : IDay
                     entity.MoveTo(_map, finalTarget.X, finalTarget.Y);
 
                     // Attack
-                    Entity targetInRangeAfterMove = GetBestInRangeTarget(entity, entitiesTargets);
+                    Entity? targetInRangeAfterMove = GetBestInRangeTarget(entity, entitiesTargets);
                     if (targetInRangeAfterMove != null)
                     {
                         entity.Attack(_map, targetInRangeAfterMove);
@@ -713,7 +715,7 @@ public class Day15 : IDay
             }
         }
 
-        private void ProcessCell(char[,] grid, char empty, Queue<BFSCell> frontier, BFSCell current, int nextX, int nextY)
+        private void ProcessCell(char[,] grid, char empty, Queue<BFSCell> frontier, BFSCell? current, int nextX, int nextY)
         {
             if (nextX < 0 || nextX >= _width || nextY < 0 || nextY >= _height) { return; }
             if (grid[nextX, nextY] == empty || current == null)

AdventOfCode2018/Day16.cs

@@ -87,8 +87,8 @@ public class Day16 : IDay
         int count = 0;
         int i = 0;
         bool end = false;
-        int[] beforeRegisters = null;
+        int[]? beforeRegisters = null;
-        int[] instruction = null;
+        int[]? instruction = null;
         const string beforeKeyword = "Before: [";
         const string afterKeyword = "After:  [";
         while (inputs.Length > i)

AdventOfCode2018/Day23.cs

@@ -68,8 +68,8 @@ public class Day23 : IDay
     public string ResolvePart1(string[] inputs)
     {
         List<NanoBot> nanoBots = NanoBot.ListFromStrings(inputs);
-        NanoBot bestNanoBot = nanoBots.OrderBy(nanoBot => nanoBot.Range).LastOrDefault();
+        NanoBot? bestNanoBot = nanoBots.OrderBy(nanoBot => nanoBot.Range).LastOrDefault();
-        int countInRange = nanoBots.Count(nanoBot => bestNanoBot.InRange(nanoBot));
+        int countInRange = nanoBots.Count(nanoBot => bestNanoBot?.InRange(nanoBot) == true);
         return countInRange.ToString();
     }
 
@@ -150,7 +150,7 @@ public class Day23 : IDay
         public long Z { get; private init; }
         public long Range { get; private init; }
 
-        private static NanoBot FromString(string strInput)
+        private static NanoBot? FromString(string strInput)
         {
             string[] parts = strInput.Split(["pos=<", ",", ">, r="], StringSplitOptions.RemoveEmptyEntries);
             if (parts.Length != 4) { return null; }
@@ -167,7 +167,7 @@ public class Day23 : IDay
         {
             List<NanoBot> nanoBots = inputs
                 .Select(FromString)
-                .Where(nanoBot => nanoBot != null)
+                .OfType<NanoBot>()
                 .ToList();
             return nanoBots;
         }

AdventOfCode2020.Tests/AdventOfCode2020.Tests.csproj

@@ -3,9 +3,11 @@
     <PropertyGroup>
         <TargetFramework>net8.0</TargetFramework>
         <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
         <RootNamespace>AdventOfCode2020.Tests</RootNamespace>
 
         <IsPackable>false</IsPackable>
+        <IsTestProject>true</IsTestProject>
     </PropertyGroup>
 
     <ItemGroup>

AdventOfCode2020/AdventOfCode2020.csproj

@@ -4,6 +4,7 @@
         <OutputType>Exe</OutputType>
         <TargetFramework>net8.0</TargetFramework>
         <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
         <RootNamespace>AdventOfCode2020</RootNamespace>
     </PropertyGroup>
 

AdventOfCode2020/Day05.cs

@@ -64,7 +64,7 @@ public class Day05 : IDay
         int maxSerialNumber = 0;
         foreach (string input in inputs)
         {
-            Seat seat = Seat_Parse(input);
+            Seat? seat = Seat_Parse(input);
             if (seat == null) { continue; }
             int newSerialNumber = seat.GetSerialNumber();
             if (newSerialNumber > maxSerialNumber) { maxSerialNumber = newSerialNumber; }
@@ -83,7 +83,7 @@ public class Day05 : IDay
         }
         foreach (string input in inputs)
         {
-            Seat seat = Seat_Parse(input);
+            Seat? seat = Seat_Parse(input);
             if (seat == null) { continue; }
 
             seats[seat.Column][seat.Row] = 'X';
@@ -166,7 +166,7 @@ public class Day05 : IDay
         }
     }
 
-    private Seat Seat_Parse(string input)
+    private Seat? Seat_Parse(string input)
     {
         if (input.Length != 10 ||
             input.All(c => c == 'F' || c == 'B' || c == 'L' || c == 'R') == false

AdventOfCode2020/Day07.cs

@@ -123,25 +123,23 @@ public class Day07 : IDay
 
     private class BaggageContainRule
     {
-        public string BagColor { get; set; }
+        public string BagColor { get; set; } = string.Empty;
         public int Count { get; init; }
     }
 
     private class BaggageRule
     {
-        public string BagColor { get; set; }
+        public string BagColor { get; set; } = string.Empty;
 
-        public List<BaggageContainRule> Contain { get; init; }
+        public List<BaggageContainRule> Contain { get; } = [];
     }
 
     private BaggageRule BaggageRule_Parse(string input)
     {
         string[] words = input.Split(' ');
         string status = "Parse Color 1";
-        BaggageRule rule = new() {
+        BaggageRule rule = new();
-            Contain = [],
+        BaggageContainRule? containRule = null;
-        };
-        BaggageContainRule containRule = null;
         string color1 = string.Empty;
 
         foreach (string word in words)
@@ -180,6 +178,7 @@ public class Day07 : IDay
                     status = "Parse Contain color 2";
                     break;
                 case "Parse Contain color 2":
+                    if(containRule == null) { break; } 
                     containRule.BagColor = string.Concat(color1, " ", word);
                     rule.Contain.Add(containRule);
                     status = "Parse Contain continue";

AdventOfCode2023.Tests/AdventOfCode2023.Tests.csproj

@@ -3,10 +3,11 @@
     <PropertyGroup>
         <TargetFramework>net8.0</TargetFramework>
         <ImplicitUsings>enable</ImplicitUsings>
-        <RootNamespace>AdventOfCode2023.Tests</RootNamespace>
         <Nullable>enable</Nullable>
+        <RootNamespace>AdventOfCode2023.Tests</RootNamespace>
 
         <IsPackable>false</IsPackable>
+        <IsTestProject>true</IsTestProject>
     </PropertyGroup>
 
     <ItemGroup>

AdventOfCode2023/AdventOfCode2023.csproj

@@ -4,8 +4,8 @@
         <OutputType>Exe</OutputType>
         <TargetFramework>net8.0</TargetFramework>
         <ImplicitUsings>enable</ImplicitUsings>
-        <RootNamespace>AdventOfCode2023</RootNamespace>
         <Nullable>enable</Nullable>
+        <RootNamespace>AdventOfCode2023</RootNamespace>
     </PropertyGroup>
 
     <ItemGroup>

AdventOfCode2024.Tests/AdventOfCode2024.Tests.csproj

@@ -3,8 +3,8 @@
     <PropertyGroup>
         <TargetFramework>net8.0</TargetFramework>
         <ImplicitUsings>enable</ImplicitUsings>
-        <RootNamespace>AdventOfCode2024.Tests</RootNamespace>
         <Nullable>enable</Nullable>
+        <RootNamespace>AdventOfCode2024.Tests</RootNamespace>
 
         <IsPackable>false</IsPackable>
         <IsTestProject>true</IsTestProject>
@@ -17,10 +17,6 @@
             <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
             <PrivateAssets>all</PrivateAssets>
         </PackageReference>
-        <PackageReference Include="coverlet.collector" Version="6.0.0">
-            <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
-            <PrivateAssets>all</PrivateAssets>
-        </PackageReference>
     </ItemGroup>
 
     <ItemGroup>

AdventOfCode2024/AdventOfCode2024.csproj

@@ -4,8 +4,8 @@
         <OutputType>Exe</OutputType>
         <TargetFramework>net8.0</TargetFramework>
         <ImplicitUsings>enable</ImplicitUsings>
-        <RootNamespace>AdventOfCode2024</RootNamespace>
         <Nullable>enable</Nullable>
+        <RootNamespace>AdventOfCode2024</RootNamespace>
     </PropertyGroup>
 
     <ItemGroup>