Added tests

Fixed edge cases with changing value

app/assets/javascripts/filtered_search/filtered_search_dropdown_manager.js.es6

@@ -62,18 +62,33 @@
 
       // Get the string to replace
       const selectionStart = input.selectionStart;
-      const { left } = gl.DropdownUtils.getInputSelectionPosition(input);
-      let { right } = gl.DropdownUtils.getInputSelectionPosition(input);
+      let { left, right } = gl.DropdownUtils.getInputSelectionPosition(input);
 
       if (right < 0) {
         right = inputValue.length;
       }
 
-      if (left !== -1) {
+      if (left < 0) {
+        left += 1;
+      }
+
       input.value = `${inputValue.substr(0, left)}${word}${inputValue.substr(right + selectionStart)}`;
-      } else {
-        input.value += word;
+      gl.FilteredSearchDropdownManager.updateInputCaretPosition(selectionStart, input);
     }
+
+    static updateInputCaretPosition(selectionStart, input) {
+      // Reset the position
+      // Sometimes can end up at end of input
+      input.setSelectionRange(selectionStart, selectionStart);
+
+      const inputValue = input.value;
+      let { right } = gl.DropdownUtils.getInputSelectionPosition(input);
+
+      if (right < 0) {
+        right = inputValue.length;
+      }
+
+      input.setSelectionRange(selectionStart + right, selectionStart + right);
     }
 
     updateCurrentDropdownOffset() {

app/assets/javascripts/filtered_search/filtered_search_manager.js.es6

@@ -194,17 +194,12 @@
       return usernamesById;
     }
 
-    tokenChange(e) {
+    tokenChange() {
       const dropdown = this.dropdownManager.mapping[this.dropdownManager.currentDropdown];
       const currentDropdownRef = dropdown.reference;
 
       this.setDropdownWrapper();
       currentDropdownRef.dispatchInputEvent();
-
-      if (e.type === 'click') {
-        // If click event, we need to trigger filter
-        this.filteredSearchInput.dispatchEvent(new Event('keyup'));
-      }
     }
   }
 

spec/features/issues/filtered_search/filter_issues_spec.rb

@@ -19,10 +19,13 @@ describe 'Filter issues', js: true, feature: true do
   let!(:closed_issue) { create(:issue, title: 'bug that is closed', project: project, state: :closed) }
   let(:filtered_search) { find('.filtered-search') }
 
-  def input_filtered_search(search_term)
+  def input_filtered_search(search_term, submit: true)
     filtered_search.set(search_term)
+
+    if submit
       filtered_search.send_keys(:enter)
     end
+  end
 
   def expect_filtered_search_input(input)
     expect(find('.filtered-search').value).to eq(input)
@@ -43,6 +46,10 @@ describe 'Filter issues', js: true, feature: true do
     end
   end
 
+  def select_search_at_index(pos)
+    evaluate_script("el = document.querySelector('.filtered-search'); el.focus(); el.setSelectionRange(#{pos}, #{pos});")
+  end
+
   before do
     project.team << [user, :master]
     project.team << [user2, :master]
@@ -522,6 +529,32 @@ describe 'Filter issues', js: true, feature: true do
     end
   end
 
+  describe 'overwrites selected filter' do
+    it 'changes author' do
+      input_filtered_search("author:@#{user.username}", submit: false)
+
+      select_search_at_index(3)
+
+      page.within '#js-dropdown-author' do
+        click_button user2.username
+      end
+
+      expect(filtered_search.value).to eq("author:@#{user2.username}")
+    end
+
+    it 'changes label' do
+      input_filtered_search("author:@#{user.username} label:~#{bug_label.title}", submit: false)
+
+      select_search_at_index(27)
+
+      page.within '#js-dropdown-label' do
+        click_button label.name
+      end
+
+      expect(filtered_search.value).to eq("author:@#{user.username} label:~#{label.name}")
+    end
+  end
+
   describe 'filter issues by text' do
     context 'only text' do
       it 'filters issues by searched text' do