Fixed module comment + underzealous double battle test override

src/@types/new-battle-props.ts

@@ -1,3 +1,11 @@
+/**
+ * A collection of types/interfaces used for {@linkcode BattleScene.newBattle} and associated
+ * sub-methods.
+ *
+ * Types are listed in order of appearance in the function.
+ * @module
+ */
+
 // biome-ignore lint/correctness/noUnusedImports: TSDoc
 import type { BattleScene } from "#app/battle-scene";
 import type { BattleType } from "#enums/battle-type";
@@ -5,14 +13,6 @@ import type { MysteryEncounterType } from "#enums/mystery-encounter-type";
 import type { Trainer } from "#field/trainer";
 import type { TrainerData } from "#system/trainer-data";
 
-/**
- * @module
- * A collection of types/interfaces used for {@linkcode BattleScene.newBattle} and associated
- * sub-methods.
- *
- * Types are listed in order of appearance in the function.
- */
-
 /** Interface representing the base type of a new battle config, used for DRY. */
 interface NewBattleBaseProps {
   /** The type of battle to create. */

src/battle-scene.ts

@@ -1534,6 +1534,12 @@ export class BattleScene extends SceneBase {
    * @returns Whether the battle should be a duouble battle.
    */
   private checkIsDouble({ double, battleType, waveIndex, trainer }: NewBattleConstructedProps): boolean {
+    const overriddenDouble = this.doCheckDoubleOverride(waveIndex);
+    // If running unit tests, overrides take precedence over normal code
+    if (import.meta.env.NODE_ENV === "test" && overriddenDouble != null) {
+      return overriddenDouble;
+    }
+
     // Edge cases
     if (
       // Wave 1 doubles cause crashes
@@ -1544,13 +1550,21 @@ export class BattleScene extends SceneBase {
     ) {
       return false;
     }
-
-    // Previously defined double battle status (from save data)
     if (double != null) {
       return double;
     }
+    if (overriddenDouble != null) {
+      return overriddenDouble;
+    }
 
-    // Overrides
+    // Standard wild battle chance
+    if (battleType === BattleType.WILD) {
+      return !randSeedInt(this.getDoubleBattleChance(waveIndex));
+    }
+    return trainer?.variant === TrainerVariant.DOUBLE;
+  }
+
+  private doCheckDoubleOverride(waveIndex: number): boolean | undefined {
     switch (Overrides.BATTLE_STYLE_OVERRIDE) {
       case "double":
         return true;
@@ -1561,12 +1575,6 @@ export class BattleScene extends SceneBase {
       case "odd-doubles":
         return waveIndex % 2 === 1;
     }
-
-    // Standard wild battle chance
-    if (battleType === BattleType.WILD) {
-      return !randSeedInt(this.getDoubleBattleChance(waveIndex));
-    }
-    return trainer?.variant === TrainerVariant.DOUBLE;
   }
 
   newArena(biome: BiomeId, playerFaints = 0): Arena {