Keep scenery files intact on save and follow them on disk

Saves keep comments and every byte they do not change. Faults in a scenery's
text are found and described. Files that change while the starter runs are
picked up without a manual reload.

StarterNG.Tests/SceneryFaultTextTests.cs

@@ -0,0 +1,77 @@
+using StarterNG.Domain.Sceneries;
+
+namespace StarterNG.Tests;
+
+public class SceneryFaultTextTests
+{
+    private static string Wording(string key) => key switch
+    {
+        "SyntaxLost" => "lost: {0}",
+        "SyntaxUnmade" => "unmade: {0}",
+        "SyntaxMore" => "and {0} more",
+        _ => key + " {0} {1}"
+    };
+
+    private static string Format(int limit, params SceneryFault[] faults) =>
+        SceneryFaultText.Format(faults, limit, Wording);
+
+    [Fact]
+    public void No_faults_read_as_nothing() =>
+        Assert.Equal("", Format(10));
+
+    [Fact]
+    public void The_place_and_the_fault_stand_in_two_columns_as_wide_as_the_longest_place()
+    {
+        string text = Format(10,
+            new SceneryFault(SceneryFaultKind.VehicleIncomplete, "a.scn", 3, "v1", "x"),
+            new SceneryFault(SceneryFaultKind.NotANumber, "long.inc", 120, "v2", "y"));
+
+        Assert.Equal(
+            "a.scn:3       SyntaxVehicleIncomplete v1 x\n" +
+            "long.inc:120  SyntaxNotANumber v2 y",
+            text);
+    }
+
+    [Fact]
+    public void What_a_fault_has_no_subject_or_token_for_is_filled_in()
+    {
+        string text = Format(10, new SceneryFault(SceneryFaultKind.StrayEndTrainset, "a.scn", 3));
+
+        Assert.Equal("a.scn:3  SyntaxStrayEndTrainset ?", text);
+    }
+
+    [Fact]
+    public void What_a_fault_costs_stands_under_it_in_the_second_column()
+    {
+        string text = Format(10,
+            new SceneryFault(SceneryFaultKind.VehicleNotClosed, "a.scn", 3, "v1", "x") { Lost = "v2, v3", Unmade = "b" });
+
+        Assert.Equal(
+            "a.scn:3  SyntaxVehicleNotClosed v1 x\n" +
+            "         lost: v2, v3\n" +
+            "         unmade: b",
+            text);
+    }
+
+    [Fact]
+    public void Past_the_limit_the_faults_are_only_counted_and_do_not_widen_the_column()
+    {
+        string text = Format(1,
+            new SceneryFault(SceneryFaultKind.NotANumber, "a.scn", 3, "v1", "x"),
+            new SceneryFault(SceneryFaultKind.NotANumber, "a-longer-name.scn", 4, "v2", "y"),
+            new SceneryFault(SceneryFaultKind.NotANumber, "a.scn", 5, "v3", "z"));
+
+        Assert.Equal(
+            "a.scn:3  SyntaxNotANumber v1 x\n" +
+            "and 2 more",
+            text);
+    }
+
+    [Fact]
+    public void Exactly_as_many_as_the_limit_are_not_counted_as_more()
+    {
+        string text = Format(1, new SceneryFault(SceneryFaultKind.NotANumber, "a.scn", 3, "v1", "x"));
+
+        Assert.DoesNotContain("more", text);
+    }
+}