From 776e095e21f0888be011ddb8ca0c647efb6f5a64 Mon Sep 17 00:00:00 2001
From: Krzysztof Modras <chrmod@chrmod.net>
Date: Wed, 11 Dec 2024 10:39:00 +0100
Subject: [PATCH] Merge: allow config differences

---
 packages/adblocker/src/engine/engine.ts       |  4 +++-
 packages/adblocker/test/engine/engine.test.ts | 22 +++++++++++++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/packages/adblocker/src/engine/engine.ts b/packages/adblocker/src/engine/engine.ts
index 25f9f6b281..299a6264ea 100644
--- a/packages/adblocker/src/engine/engine.ts
+++ b/packages/adblocker/src/engine/engine.ts
@@ -290,7 +290,9 @@ export default class FilterEngine extends EventEmitter<EngineEventHandlers> {
     const configKeysMustMatch: ConfigKey[] = (Object.keys(config) as (keyof Config)[]).filter(
       function (key): key is ConfigKey {
         return (
-          typeof config[key] === 'boolean' && !compatibleConfigKeys.includes(key as ConfigKey)
+          typeof config[key] === 'boolean' &&
+          !compatibleConfigKeys.includes(key as ConfigKey) &&
+          !Object.hasOwnProperty.call(overrideConfig, key)
         );
       },
     );
diff --git a/packages/adblocker/test/engine/engine.test.ts b/packages/adblocker/test/engine/engine.test.ts
index ab25272e6b..e52fe38d3a 100644
--- a/packages/adblocker/test/engine/engine.test.ts
+++ b/packages/adblocker/test/engine/engine.test.ts
@@ -2023,6 +2023,28 @@ foo.com###selector
       });
     });
 
+    context.only('valides configs', () => {
+      it('throws with different configs', () => {
+        const engine1 = FilterEngine.empty({ loadCosmeticFilters: true });
+        const engine2 = FilterEngine.empty({ loadCosmeticFilters: false });
+        expect(() => FilterEngine.merge([engine1, engine2])).to.throw(
+          `config "loadCosmeticFilters" of all merged engines must be the same`,
+        );
+      });
+
+      it('does not check overridden configs', () => {
+        const engine1 = FilterEngine.empty({ enableCompression: true });
+        const engine2 = FilterEngine.empty({ enableCompression: false });
+        let engine: FilterEngine;
+        expect(() => {
+          engine = FilterEngine.merge([engine1, engine2], {
+            overrideConfig: { enableCompression: false },
+          });
+        }).not.to.throw();
+        expect(engine!.config).to.have.property('enableCompression').that.equal(false);
+      });
+    });
+
     context('with resources', () => {
       it('throws with different checksums', () => {
         const engine1 = FilterEngine.empty();