Keep the crew when a vehicle is swapped in the depot

The crew was copied to the card but not to the new cars, which are what is
shown and exported, so a swapped locomotive came out unstaffed. Swapping now
moves the crew over and otherwise staffs the vehicle as adding would.

StarterNG.Tests/ConsistCrewTests.cs

@@ -0,0 +1,107 @@
+using StarterNG.Classes;
+using StarterNG.Domain;
+using StarterNG.Domain.Vehicles;
+using StarterNG.Tests.Fakes;
+
+namespace StarterNG.Tests;
+
+public class ConsistCrewTests
+{
+    private readonly Consist _consist;
+    private readonly VehicleCatalog _catalog;
+
+    public ConsistCrewTests()
+    {
+        var installation = new TestInstallation(new InMemoryFileSystem()
+            .WithFile(TestInstallation.At("dynamic", "pkp", "ep07", "textures.txt"),
+                      "!=e\nep07-001.mat=ep07,EP07\nep07-002.mat=ep07,EP07")
+            .WithFile(TestInstallation.At("dynamic", "pkp", "b111", "textures.txt"),
+                      "!=b\nb111-01.mat=b111,B111"));
+        installation.Vehicles.Load(installation.Library.Vehicles);
+
+        _catalog = installation.Library.Vehicles;
+        _consist = new Consist(_catalog, new VehicleInfo(_catalog));
+    }
+
+    [Fact]
+    public void A_locomotive_added_at_the_head_gets_a_driver_in_cab_a()
+    {
+        var loco = Add("ep07-001", 0);
+
+        Assert.Equal(eDriverType.Headdriver, loco.Cars[0].DriverType);
+    }
+
+    [Fact]
+    public void Replacing_the_locomotive_keeps_the_driver_on_the_new_one()
+    {
+        Add("ep07-001", 0);
+        Add("b111-01", 1);
+
+        var replacement = Replace(0, "ep07-002");
+
+        Assert.Equal(eDriverType.Headdriver, replacement.Cars[0].DriverType);
+        Assert.Equal(eDriverType.Headdriver, replacement.Driver);
+    }
+
+    [Fact]
+    public void An_unstaffed_locomotive_replaced_at_the_head_is_staffed_in_cab_a()
+    {
+        var loco = Add("ep07-001", 0);
+        loco.Cars[0].DriverType = eDriverType.Nobody;
+        loco.Driver = eDriverType.Nobody;
+
+        var replacement = Replace(0, "ep07-002");
+
+        Assert.Equal(eDriverType.Headdriver, replacement.Cars[0].DriverType);
+    }
+
+    [Fact]
+    public void A_driver_in_cab_b_stays_in_cab_b()
+    {
+        var loco = Add("ep07-001", 0);
+        loco.Cars[0].DriverType = eDriverType.Reardriver;
+        loco.Driver = eDriverType.Reardriver;
+
+        var replacement = Replace(0, "ep07-002");
+
+        Assert.Equal(eDriverType.Reardriver, replacement.Cars[0].DriverType);
+    }
+
+    [Fact]
+    public void A_wagon_put_in_place_of_the_locomotive_gets_no_driver()
+    {
+        Add("ep07-001", 0);
+
+        var wagon = Replace(0, "b111-01");
+
+        Assert.Equal(eDriverType.Nobody, wagon.Cars[0].DriverType);
+    }
+
+    [Fact]
+    public void A_second_locomotive_behind_a_staffed_one_stays_unstaffed()
+    {
+        Add("ep07-001", 0);
+
+        var second = Add("ep07-002", 1);
+
+        Assert.Equal(eDriverType.Nobody, second.Cars[0].DriverType);
+    }
+
+    private ConsistItem Add(string skin, int at)
+    {
+        var item = Item(skin);
+        _consist.Staff(item, at);
+        _consist.Insert(at, item);
+        return item;
+    }
+
+    private ConsistItem Replace(int at, string skin)
+    {
+        var item = Item(skin);
+        _consist.Replace(at, item);
+        return item;
+    }
+
+    private ConsistItem Item(string skin) =>
+        new() { Cars = new List<Dynamic> { _consist.MakeDynamic(_catalog.TextureForSkin(skin)!, null) } };
+}