Add Season.First, replacing FIRST_TURN

MultiversalDiplomacy/Model/Season.cs

@@ -10,9 +10,10 @@ namespace MultiversalDiplomacy.Model;
 public struct Season(string timeline, int turn)
 {
     /// <summary>
-    /// The first turn number. This is defined to reduce confusion about whether the first turn is 0 or 1.
+    /// The root season of every game. This is defined to avoid any confusion about what the first turn or timeline
+    /// should be or what season to use to key into a fresh <see cref="Timelines"/>.
     /// </summary>
-    public const int FIRST_TURN = 0;
+    public static readonly Season First = new(Timelines.IntToString(0), 0);
 
     /// <summary>
     /// The timeline to which this season belongs.

MultiversalDiplomacy/Model/Timelines.cs

@@ -75,10 +75,7 @@ public class Timelines(int next, Dictionary<string, Season?> pasts)
     /// Create a new multiverse with an initial season.
     /// </summary>
     public static Timelines Create()
-    {
+        => new(StringToInt(Season.First.Timeline) + 1, new() { {Season.First.Key, null} });
-        Season first = new(IntToString(0), Season.FIRST_TURN);
-        return new Timelines(1, new() { {first.Key, null} });
-    }
 
     /// <summary>
     /// Create a continuation of a season if it has no futures, otherwise create a fork.

MultiversalDiplomacy/Model/World.cs

@@ -181,7 +181,7 @@ public class World
                 : splits.Length == 3
                     ? Map.GetWater(splits[2])
                     : Map.GetWater(splits[2], splits[3]);
-            Unit unit = Unit.Build(location.Key, new("a0"), power, type);
+            Unit unit = Unit.Build(location.Key, Season.First, power, type);
             return unit;
         });
         return this.Update(units: units);
@@ -229,7 +229,7 @@ public class World
     public Unit GetUnitAt(string provinceName, Season? season = null)
     {
         Province province = Map.GetProvince(provinceName);
-        season ??= new("a0");
+        season ??= Season.First;
         Unit? foundUnit = this.Units.SingleOrDefault(
             u => Map.GetLocation(u!).Province == province && u!.Season == season,
             null)

MultiversalDiplomacyTests/Model/TimelineFactoryTest.cs

@@ -36,12 +36,12 @@ public class TimelineFactoryTest
     public void NoSharedFactoryState()
     {
         Timelines one = Timelines.Create()
-            .WithNewSeason(new Season("a0"), out var s1)
+            .WithNewSeason(Season.First, out var s1)
-            .WithNewSeason(new Season("a0"), out var s2)
+            .WithNewSeason(Season.First, out var s2)
-            .WithNewSeason(new Season("a0"), out var s3);
+            .WithNewSeason(Season.First, out var s3);
         Timelines two = Timelines.Create()
-            .WithNewSeason(new Season("a0"), out var s4)
+            .WithNewSeason(Season.First, out var s4)
-            .WithNewSeason(new Season("a0"), out var s5);
+            .WithNewSeason(Season.First, out var s5);
 
         Assert.That(s1.Timeline, Is.EqualTo("a"));
         Assert.That(s2.Timeline, Is.EqualTo("b"));
@@ -54,14 +54,14 @@ public class TimelineFactoryTest
     public void TimelineForking()
     {
         Timelines timelines = Timelines.Create()
-            .WithNewSeason("a0", out var a1)
+            .WithNewSeason(Season.First, out var a1)
             .WithNewSeason(a1, out var a2)
             .WithNewSeason(a2, out var a3)
             .WithNewSeason(a1, out var b2)
             .WithNewSeason(b2, out var b3)
             .WithNewSeason(a1, out var c2)
             .WithNewSeason(a2, out var d3);
-        Season a0 = new("a0");
+        Season a0 = Season.First;
 
         Assert.That(
             timelines.Pasts.Keys,
@@ -76,13 +76,13 @@ public class TimelineFactoryTest
         Assert.That(c2.Timeline, Is.EqualTo("c"), "Unexpected second alt");
         Assert.That(d3.Timeline, Is.EqualTo("d"), "Unexpected third alt");
 
-        Assert.That(a1.Turn, Is.EqualTo(Season.FIRST_TURN + 1), "Unexpected a1 turn number");
+        Assert.That(a1.Turn, Is.EqualTo(Season.First.Turn + 1), "Unexpected a1 turn number");
-        Assert.That(a2.Turn, Is.EqualTo(Season.FIRST_TURN + 2), "Unexpected a2 turn number");
+        Assert.That(a2.Turn, Is.EqualTo(Season.First.Turn + 2), "Unexpected a2 turn number");
-        Assert.That(a3.Turn, Is.EqualTo(Season.FIRST_TURN + 3), "Unexpected a3 turn number");
+        Assert.That(a3.Turn, Is.EqualTo(Season.First.Turn + 3), "Unexpected a3 turn number");
-        Assert.That(b2.Turn, Is.EqualTo(Season.FIRST_TURN + 2), "Unexpected b2 turn number");
+        Assert.That(b2.Turn, Is.EqualTo(Season.First.Turn + 2), "Unexpected b2 turn number");
-        Assert.That(b3.Turn, Is.EqualTo(Season.FIRST_TURN + 3), "Unexpected b3 turn number");
+        Assert.That(b3.Turn, Is.EqualTo(Season.First.Turn + 3), "Unexpected b3 turn number");
-        Assert.That(c2.Turn, Is.EqualTo(Season.FIRST_TURN + 2), "Unexpected c2 turn number");
+        Assert.That(c2.Turn, Is.EqualTo(Season.First.Turn + 2), "Unexpected c2 turn number");
-        Assert.That(d3.Turn, Is.EqualTo(Season.FIRST_TURN + 3), "Unexpected d3 turn number");
+        Assert.That(d3.Turn, Is.EqualTo(Season.First.Turn + 3), "Unexpected d3 turn number");
 
         Assert.That(timelines.GetTimelineRoot(a0), Is.EqualTo(a0), "Expected timeline root to be reflexive");
         Assert.That(timelines.GetTimelineRoot(a3), Is.EqualTo(a0), "Expected trunk timeline to have root");

MultiversalDiplomacyTests/SerializationTest.cs

@@ -65,9 +65,9 @@ public class SerializationTest
         Assert.That(tyr0, Is.NotDislodged);
         setup.UpdateWorld();
 
-        Assert.That(setup.World.OrderHistory["a0"].Orders.Count, Is.GreaterThan(0), "Missing orders");
+        Assert.That(setup.World.OrderHistory[s0.Key].Orders.Count, Is.GreaterThan(0), "Missing orders");
-        Assert.That(setup.World.OrderHistory["a0"].DoesMoveOutcomes.Count, Is.GreaterThan(0), "Missing moves");
+        Assert.That(setup.World.OrderHistory[s0.Key].DoesMoveOutcomes.Count, Is.GreaterThan(0), "Missing moves");
-        Assert.That(setup.World.OrderHistory["a0"].IsDislodgedOutcomes.Count, Is.GreaterThan(0), "Missing dislodges");
+        Assert.That(setup.World.OrderHistory[s0.Key].IsDislodgedOutcomes.Count, Is.GreaterThan(0), "Missing dislodges");
 
         // Serialize and deserialize the world
         string serialized = JsonSerializer.Serialize(setup.World, Options);
@@ -75,9 +75,9 @@ public class SerializationTest
             ?? throw new AssertionException("Failed to reserialize world");
 
         Assert.Multiple(() => {
-            Assert.That(reserialized.OrderHistory["a0"].Orders.Count, Is.GreaterThan(0), "Missing orders");
+            Assert.That(reserialized.OrderHistory[s0.Key].Orders.Count, Is.GreaterThan(0), "Missing orders");
-            Assert.That(reserialized.OrderHistory["a0"].DoesMoveOutcomes.Count, Is.GreaterThan(0), "Missing moves");
+            Assert.That(reserialized.OrderHistory[s0.Key].DoesMoveOutcomes.Count, Is.GreaterThan(0), "Missing moves");
-            Assert.That(reserialized.OrderHistory["a0"].IsDislodgedOutcomes.Count, Is.GreaterThan(0), "Missing dislodges");
+            Assert.That(reserialized.OrderHistory[s0.Key].IsDislodgedOutcomes.Count, Is.GreaterThan(0), "Missing dislodges");
         });
 
         Assert.Ignore("Serialization doesn't fully work yet");
@@ -86,7 +86,7 @@ public class SerializationTest
         setup = new(reserialized, MovementPhaseAdjudicator.Instance);
         setup[("a", 1)]
             ["Germany"]
-                .Army("Mun").Supports.Army("Mun", season: new("a0")).MoveTo("Tyr").GetReference(out var mun1)
+                .Army("Mun").Supports.Army("Mun", season: s0).MoveTo("Tyr").GetReference(out var mun1)
             ["Austria"]
                 .Army("Tyr").Holds();
 

MultiversalDiplomacyTests/UnitTests.cs

@@ -13,7 +13,7 @@ public class UnitTests
         Location Mun = world.Map.GetLand("Mun"),
             Boh = world.Map.GetLand("Boh"),
             Tyr = world.Map.GetLand("Tyr");
-        Season a0 = new("a0");
+        Season a0 = Season.First;
         Unit u1 = Unit.Build(Mun.Key, a0, "Austria", UnitType.Army);
 
         world = world.WithNewSeason(a0, out Season a1);