diff --git a/src/system/game-data.test.ts b/src/system/game-data.test.ts
new file mode 100644
index 00000000000..867da7fd4bf
--- /dev/null
+++ b/src/system/game-data.test.ts
@@ -0,0 +1,50 @@
+import { expect, describe, it, beforeAll, vi, afterAll } from "vitest";
+import { GameDataType, getDataTypeKey } from "./game-data";
+
+describe("game-data", () => {
+  describe("getDataTypeKey", () => {
+    beforeAll(() => {
+      // Error when importing biomes (imported by different files)
+      vi.mock('../data/biomes', () => ({
+        biomeLinks: {},
+        BiomePoolTier: {},
+        PokemonPools: {},
+        getBiomeName: () => "",
+        BiomeTierTrainerPools: {},
+        biomePokemonPools: {},
+        biomeTrainerPools: {},
+      }));
+    });
+
+    afterAll(() => {
+      vi.clearAllMocks();
+    });
+
+    it("returns sessionData for session data type", () => {
+      expect(getDataTypeKey(GameDataType.SESSION)).toBe("sessionData");
+      expect(getDataTypeKey(GameDataType.SESSION, 0)).toBe("sessionData");
+    });
+
+    it("returns sessionData with the slot id given for session data type", () => {
+      expect(getDataTypeKey(GameDataType.SESSION, 1)).toBe("sessionData1");
+    });
+
+    it("returns data for system data type", () => {
+      expect(getDataTypeKey(GameDataType.SYSTEM)).toBe("data");
+      expect(getDataTypeKey(GameDataType.SYSTEM, 0)).toBe("data");
+      expect(getDataTypeKey(GameDataType.SYSTEM, 1)).toBe("data");
+    });
+
+    it("returns settings for settings data type", () => {
+      expect(getDataTypeKey(GameDataType.SETTINGS)).toBe("settings");
+      expect(getDataTypeKey(GameDataType.SETTINGS, 0)).toBe("settings");
+      expect(getDataTypeKey(GameDataType.SETTINGS, 1)).toBe("settings");
+    });
+
+    it("returns tutorials for tutorials data type", () => {
+      expect(getDataTypeKey(GameDataType.TUTORIALS)).toBe("tutorials");
+      expect(getDataTypeKey(GameDataType.TUTORIALS, 0)).toBe("tutorials");
+      expect(getDataTypeKey(GameDataType.TUTORIALS, 1)).toBe("tutorials");
+    });
+  });
+});
diff --git a/src/system/game-data.ts b/src/system/game-data.ts
index 60fe7ac8e02..8db9baf5f42 100644
--- a/src/system/game-data.ts
+++ b/src/system/game-data.ts
@@ -55,10 +55,7 @@ export function getDataTypeKey(dataType: GameDataType, slotId: integer = 0): str
     case GameDataType.SYSTEM:
       return 'data';
     case GameDataType.SESSION:
-      let ret = 'sessionData';
-      if (slotId)
-        ret += slotId;
-      return ret;
+      return `sessionData${slotId ? slotId : ''}`;
     case GameDataType.SETTINGS:
       return 'settings';
     case GameDataType.TUTORIALS: