FIX: Advanced search should retain search term.

app/assets/javascripts/discourse/widgets/search-menu-controls.js.es6

@@ -44,9 +44,12 @@ createWidget('search-context', {
                   ]));
     }
 
-    result.push(this.attach('link', { href: Discourse.getURL('/search?expanded=true'),
+    if (!attrs.contextEnabled) {
+      result.push(this.attach('link', { href: attrs.url,
                                         label: 'show_help',
                                         className: 'show-help' }));
+    }
+
     result.push(h('div.clearfix'));
     return result;
   },

app/assets/javascripts/discourse/widgets/search-menu.js.es6

@@ -67,7 +67,7 @@ const SearchHelper = {
 export default createWidget('search-menu', {
   tagName: 'div.search-menu',
 
-  fullSearchUrl() {
+  fullSearchUrl(opts) {
     const contextEnabled = searchData.contextEnabled;
 
     const ctx = contextEnabled ? this.searchContext() : null;
@@ -77,25 +77,46 @@ export default createWidget('search-menu', {
       return;
     }
 
-    let url = '/search?q=' + encodeURIComponent(searchData.term);
+    let url = '/search';
+    const params = [];
+
+    if (searchData.term) {
+      let query = '';
+
+      query += `q=${encodeURIComponent(searchData.term)}`;
+
       if (contextEnabled) {
         if (this.currentUser &&
             ctx.id.toString().toLowerCase() === this.currentUser.username_lower &&
             type === "private_messages") {
-        url += ' in:private';
+          query += ' in:private';
         } else {
-        url += encodeURIComponent(" " + type + ":" + ctx.id);
+          query += encodeURIComponent(" " + type + ":" + ctx.id);
         }
       }
 
+      if (query) params.push(query);
+    }
+
+    if (opts && opts.expanded) params.push('expanded=true');
+
+    if (params.length > 0) {
+      url = `${url}?${params.join("&")}`;
+    }
+
     return Discourse.getURL(url);
   },
 
   panelContents() {
     const contextEnabled = searchData.contextEnabled;
 
-    const results = [this.attach('search-term', { value: searchData.term, contextEnabled }),
-                     this.attach('search-context', { contextEnabled })];
+    const results = [
+      this.attach('search-term', { value: searchData.term, contextEnabled }),
+      this.attach('search-context', {
+        contextEnabled,
+        url: this.fullSearchUrl({ expanded: true })
+      })
+    ];
 
     if (searchData.term) {
       if (searchData.loading) {

test/javascripts/acceptance/search-test.js.es6

@@ -16,4 +16,11 @@ test("search", (assert) => {
   andThen(() => {
     assert.ok(exists('.search-menu .results ul li'), 'it shows results');
   });
+
+  click('.show-help');
+
+  andThen(() => {
+    assert.equal(find('.full-page-search').val(), 'dev', 'it shows the search term');
+    assert.ok(exists('.search-advanced-options'), 'advanced search is expanded');
+  });
 });