fix(sortBy): do not write the default state (#4798)

Without this check, if a route state is read (eg. in ssr) with the default value, it will be persisted in the URL, as the refinement is the default refinement, and the ui state was kept as-is, instead of being cleared.

fixes algolia/vue-instantsearch#1005

Author: Haroenv

src/connectors/sort-by/__tests__/connectSortBy-test.ts

@@ -547,7 +547,7 @@ See documentation: https://www.algolia.com/doc/api-reference/widgets/sort-by/js/
         const [widget, helper] = getInitializedWidget();
 
         const uiStateBefore = {};
-        const uiStateAfter = widget.getWidgetUiState!(uiStateBefore, {
+        const uiStateAfter = widget.getWidgetUiState(uiStateBefore, {
           searchParameters: helper.state,
           helper,
         });
@@ -561,7 +561,7 @@ See documentation: https://www.algolia.com/doc/api-reference/widgets/sort-by/js/
         refine('priceASC');
 
         const uiStateBefore = {};
-        const uiStateAfter = widget.getWidgetUiState!(uiStateBefore, {
+        const uiStateAfter = widget.getWidgetUiState(uiStateBefore, {
           searchParameters: helper.state,
           helper,
         });
@@ -576,21 +576,41 @@ See documentation: https://www.algolia.com/doc/api-reference/widgets/sort-by/js/
 
         refine('priceASC');
 
-        const uiStateBefore = widget.getWidgetUiState!(
+        const uiStateBefore = widget.getWidgetUiState(
           {},
           {
             searchParameters: helper.state,
             helper,
           }
         );
-        const uiStateAfter = widget.getWidgetUiState!(uiStateBefore, {
+        const uiStateAfter = widget.getWidgetUiState(uiStateBefore, {
           searchParameters: helper.state,
           helper,
         });
 
         expect(uiStateAfter).toEqual(uiStateBefore);
       });
 
+      test('should remove refinement if new refinement is the initial index', () => {
+        const [widget, helper] = getInitializedWidget();
+
+        expect(helper.state.index).toBe('relevance');
+
+        expect(
+          widget.getWidgetUiState(
+            {
+              sortBy: 'relevance',
+            },
+            {
+              searchParameters: helper.state,
+              helper,
+            }
+          )
+        ).toEqual({
+          sortBy: undefined,
+        });
+      });
+
       test('should use the top-level `indexName` for the initial index', () => {
         const render = jest.fn();
         const makeWidget = connectSortBy(render);
@@ -622,7 +642,7 @@ See documentation: https://www.algolia.com/doc/api-reference/widgets/sort-by/js/
           })
         );
 
-        const actual = widget.getWidgetUiState!(
+        const actual = widget.getWidgetUiState(
           {},
           {
             searchParameters: helper.state,
@@ -657,7 +677,6 @@ See documentation: https://www.algolia.com/doc/api-reference/widgets/sort-by/js/
           createSearchClient(),
           'indexNameParent'
         );
-        helper.search = jest.fn();
 
         widget.init!(
           createInitOptions({
@@ -668,7 +687,7 @@ See documentation: https://www.algolia.com/doc/api-reference/widgets/sort-by/js/
           })
         );
 
-        const actual = widget.getWidgetUiState!(
+        const actual = widget.getWidgetUiState(
           {},
           {
             searchParameters: helper.state,

src/connectors/sort-by/connectSortBy.ts

@@ -177,13 +177,12 @@ const connectSortBy: SortByConnector = function connectSortBy(
       getWidgetUiState(uiState, { searchParameters }) {
         const currentIndex = searchParameters.index;
 
-        if (currentIndex === connectorState.initialIndex) {
-          return uiState;
-        }
-
         return {
           ...uiState,
-          sortBy: currentIndex,
+          sortBy:
+            currentIndex !== connectorState.initialIndex
+              ? currentIndex
+              : undefined,
         };
       },