Implement live game clock and simulation controls; enhance API with clock update functionality and improve world summary with clock data; update UI to display simulation controls and integrate clock features into the game experience.

tests/TheLivingWorld.Tests/GameTimeTests.cs

@@ -0,0 +1,61 @@
+using TheLivingWorld.Core.Simulation;
+
+namespace TheLivingWorld.Tests;
+
+public sealed class GameTimeTests
+{
+    [Fact]
+    public void Advance_at_x1_adds_five_game_minutes_per_real_second()
+    {
+        var start = GameTime.DefaultStart;
+        var next = GameTime.Advance(start, TimeSpan.FromSeconds(1), timeScale: 1, paused: false);
+
+        Assert.Equal(start.AddMinutes(5), next);
+    }
+
+    [Fact]
+    public void Advance_scales_with_time_scale()
+    {
+        var start = GameTime.DefaultStart;
+
+        Assert.Equal(start.AddMinutes(10), GameTime.Advance(start, TimeSpan.FromSeconds(1), 2, false));
+        Assert.Equal(start.AddMinutes(20), GameTime.Advance(start, TimeSpan.FromSeconds(1), 4, false));
+    }
+
+    [Fact]
+    public void Advance_does_nothing_when_paused_or_non_positive()
+    {
+        var start = GameTime.DefaultStart;
+
+        Assert.Equal(start, GameTime.Advance(start, TimeSpan.FromSeconds(10), 4, paused: true));
+        Assert.Equal(start, GameTime.Advance(start, TimeSpan.Zero, 1, paused: false));
+        Assert.Equal(start, GameTime.Advance(start, TimeSpan.FromSeconds(-1), 1, paused: false));
+    }
+
+    [Fact]
+    public void Advance_handles_a_large_wall_clock_gap()
+    {
+        var start = GameTime.DefaultStart;
+        // One real hour at x1 → 5 * 3600 = 18_000 game minutes = 12.5 game days.
+        var next = GameTime.Advance(start, TimeSpan.FromHours(1), timeScale: 1, paused: false);
+
+        Assert.Equal(start.AddMinutes(5 * 3600), next);
+        Assert.Equal(new DateTime(2012, 4, 24, 18, 0, 0, DateTimeKind.Unspecified), next);
+    }
+
+    [Fact]
+    public void DefaultStart_is_morning_of_12_April_2012()
+    {
+        Assert.Equal(new DateTime(2012, 4, 12, 6, 0, 0, DateTimeKind.Unspecified), GameTime.DefaultStart);
+    }
+
+    [Theory]
+    [InlineData(1, true)]
+    [InlineData(4, true)]
+    [InlineData(0, false)]
+    [InlineData(5, false)]
+    public void IsValidTimeScale_accepts_1_through_4(int scale, bool expected)
+    {
+        Assert.Equal(expected, GameTime.IsValidTimeScale(scale));
+    }
+}