fix(searchParameters): avoid mutating provided objects

src/lib/InstantSearch.js

@@ -6,6 +6,7 @@ import forEach from 'lodash/collection/forEach';
 import merge from 'lodash/object/merge';
 import union from 'lodash/array/union';
 import clone from 'lodash/lang/clone';
+import isObject from 'lodash/lang/isObject';
 import {EventEmitter} from 'events';
 import urlSyncWidget from './url-sync.js';
 import version from './version.js';
@@ -194,19 +195,28 @@ Usage: instantsearch({
 function enhanceConfiguration(configuration, widgetDefinition) {
   if (!widgetDefinition.getConfiguration) return configuration;
 
-  // Update searchParameters with the configuration from the widgets
+  // Get the relevant partial configuration asked by the widget
   const partialConfiguration = widgetDefinition.getConfiguration(configuration);
+
+  const customizer = (a, b) => {
+    // always create a unified array for facets refinements
+    if (Array.isArray(a)) {
+      return union(a, b);
+    }
+
+    // avoid mutating objects
+    if (isObject(a)) {
+      return merge({}, a, b, customizer);
+    }
+
+    return undefined;
+  };
+
   return merge(
     {},
     configuration,
     partialConfiguration,
-    (a, b) => {
-      if (Array.isArray(a)) {
-        return union(a, b);
-      }
-
-      return undefined;
-    }
+    customizer
   );
 }
 

src/lib/__tests__/InstantSearch-test.js

@@ -113,6 +113,26 @@ describe('InstantSearch lifecycle', () => {
     expect(helperSearchSpy.calledOnce).toBe(false);
   });
 
+  it('does not fail when passing same references inside multiple searchParameters props', () => {
+    const disjunctiveFacetsRefinements = {fruits: ['apple']};
+    const facetsRefinements = disjunctiveFacetsRefinements;
+    search = new InstantSearch({
+      appId,
+      apiKey,
+      indexName,
+      searchParameters: {
+        disjunctiveFacetsRefinements,
+        facetsRefinements
+      }
+    });
+    search.addWidget({
+      getConfiguration: () => ({disjunctiveFacetsRefinements: {fruits: ['orange']}}),
+      init: () => {}
+    });
+    search.start();
+    expect(search.searchParameters.facetsRefinements).toEqual({fruits: ['apple']});
+  });
+
   context('when adding a widget', () => {
     let widget;