Implement forward bisect

lib/mod_list_troubleshooter.dart

@@ -15,12 +15,21 @@ import 'package:rimworld_modman/mod_list.dart';
 class ModListTroubleshooter {
   final ModList originalModList;
   ModList currentModList;
+  int _startIndex = 0;
+  int _endIndex = 0;
 
   ModListTroubleshooter(ModList modList)
     : originalModList = modList,
-      currentModList = modList.copyWith();
+      currentModList = modList.copyWith(),
+      _startIndex = 0,
+      _endIndex = modList.activeMods.length;
 
   ModList binaryForward() {
+    final midIndex = (_startIndex + _endIndex) ~/ 2;
+    final subset = originalModList.activeMods.keys.toList().sublist(midIndex);
+    currentModList.disableAll();
+    currentModList.enableMods(subset);
+    _startIndex = midIndex;
     return currentModList;
   }
 

test/mod_list_troubleshooter_test.dart

@@ -50,7 +50,7 @@ Mod makeDummy() {
 
 void main() {
   group('ModListTroubleshooter Bisect Tests', () {
-    late ModList modList;
+    late ModList modList = ModList();
     setUp(() {
       modList = ModList();
 
@@ -71,21 +71,30 @@ void main() {
         );
         modList.mods[modId] = mod;
       }
+      modList.enableAll();
     });
-    modList.enableAll();
 
     test(
-      'Bisect search should end up with half the mods every iteration until 1',
+      'Bisect search should end up with half the mods every forward iteration until 1',
       () {
         final troubleshooter = ModListTroubleshooter(modList);
 
-        final result = troubleshooter.binaryForward();
+        var result = troubleshooter.binaryForward();
         // Half of our initial 30
         expect(result.activeMods.length, equals(15));
 
-        final result2 = troubleshooter.binaryBackward();
+        result = troubleshooter.binaryForward();
         // Half of our previous result
-        expect(result2.activeMods.length, equals(7));
+        expect(result.activeMods.length, equals(8));
+
+        result = troubleshooter.binaryForward();
+        expect(result.activeMods.length, equals(4));
+
+        result = troubleshooter.binaryForward();
+        expect(result.activeMods.length, equals(2));
+
+        result = troubleshooter.binaryForward();
+        expect(result.activeMods.length, equals(1));
       },
     );
   });