Preserve trailing space when exiting custom search engine

background_scripts/completion/completers.js

@@ -748,7 +748,8 @@ export class MultiCompleter {
       return [];
     }
 
-    const queryMatchesUserSearchEngine = searchEngineCompleter?.getUserSearchEngineForQuery(query);
+    const queryMatchesUserSearchEngine = !request.isUserSearchEngineEscaped &&
+      searchEngineCompleter?.getUserSearchEngineForQuery(query);
 
     // If the user's query matches one of their custom search engines, then use only that engine to
     // provide completions for their query.

pages/vomnibar_page.js

@@ -63,6 +63,7 @@ class VomnibarUI {
     // The user's custom search engine, if they have prefixed their query with the keyword for one
     // of their search engines.
     this.activeUserSearchEngine = null;
+    this.escapedUserSearchEngine = null;
     // Used for synchronizing requests and responses to the background page.
     this.lastRequestId = null;
   }
@@ -72,6 +73,7 @@ class VomnibarUI {
   }
   setActiveUserSearchEngine(userSearchEngine) {
     this.activeUserSearchEngine = userSearchEngine;
+    this.escapedUserSearchEngine = null;
   }
   setInitialSelectionValue(initialSelectionValue) {
     this.initialSelectionValue = initialSelectionValue;
@@ -129,6 +131,7 @@ class VomnibarUI {
     this.renderCompletions(this.completions);
     this.previousInputValue = null;
     this.activeUserSearchEngine = null;
+    this.escapedUserSearchEngine = null;
     this.selection = this.initialSelectionValue;
     this.seenTabToOpenCompletionList = false;
     this.lastRequestId = null;
@@ -243,10 +246,17 @@ class VomnibarUI {
         // Normally, with custom search engines, the keyword (e.g. the "w" of "w query terms") is
         // suppressed. If the cursor is at the start of the input, then reinstate the keyword (the
         // "w").
-        const keyword = this.activeUserSearchEngine.keyword;
+        this.escapedUserSearchEngine = this.activeUserSearchEngine;
+        const keyword = this.escapedUserSearchEngine.keyword + " ";
         this.input.value = keyword + this.input.value.trimStart();
         this.input.selectionStart = this.input.selectionEnd = keyword.length;
         this.activeUserSearchEngine = null;
+        // The current completions belong to the custom search engine. Clear them synchronously so
+        // that pressing Enter before the replacement completions arrive uses the default search.
+        this.completions = [];
+        this.renderCompletions(this.completions);
+        this.previousInputValue = null;
+        this.selection = this.initialSelectionValue;
         this.update();
       } else if (this.seenTabToOpenCompletionList && (this.input.value.trim().length === 0)) {
         this.seenTabToOpenCompletionList = false;
@@ -359,6 +369,7 @@ class VomnibarUI {
       completerName: this.completerName,
       queryTerms,
       query,
+      isUserSearchEngineEscaped: this.escapedUserSearchEngine != null,
       seenTabToOpenCompletionList: this.seenTabToOpenCompletionList,
     });
 
@@ -402,8 +413,12 @@ class VomnibarUI {
 
     // For custom search engines, we suppress the leading prefix (e.g. the "w" of "w query terms")
     // within the vomnibar input.
-    if (!this.isUserSearchEngineActive() && this.getUserSearchEngineForQuery() != null) {
-      this.activeUserSearchEngine = this.getUserSearchEngineForQuery();
+    const userSearchEngine = this.getUserSearchEngineForQuery();
+    if (this.escapedUserSearchEngine != userSearchEngine) {
+      this.escapedUserSearchEngine = null;
+    }
+    if (!this.isUserSearchEngineActive() && !this.escapedUserSearchEngine && userSearchEngine) {
+      this.activeUserSearchEngine = userSearchEngine;
       const queryTerms = this.input.value.trim().split(/\s+/);
       this.input.value = queryTerms.slice(1).join(" ");
     }

tests/unit_tests/completion/completers_test.js

@@ -367,6 +367,19 @@ context("multi completer", () => {
     assert.equal("http://example.com", results[0].url);
     assert.equal("http://other.com", results[1].url);
   });
+
+  should("distinguish escaped and prefilled custom search engines", async () => {
+    userSearchEngines.set("e: https://example.com/?q=%s");
+    const fallback = new Suggestion({ url: "fallback", relevancy: 1, queryTerms: ["e"] });
+    const search = new SearchEngineCompleter();
+    const completer = new MultiCompleter([{ filter: () => [fallback] }, search]);
+    const request = { query: "e ", queryTerms: ["e"], isUserSearchEngineEscaped: true };
+    assert.equal([fallback], await completer.filter(request));
+    request.query = "e hello";
+    request.queryTerms.push("hello");
+    request.isUserSearchEngineEscaped = false;
+    assert.isTrue((await completer.filter(request))[0].isCustomSearch);
+  });
 });
 
 context("command completer", () => {

tests/unit_tests/vomnibar_page_test.js

@@ -122,6 +122,41 @@ context("vomnibar page", () => {
     assert.equal("https://www.example.com/search?q=hello", capturedUrl);
   });
 
+  should("preserve default completions after exiting a custom search engine", async () => {
+    userSearchEngines.set("e: https://www.example.com/search?q=%s Example");
+    let isUserSearchEngineEscaped;
+    let launchedSearchQuery;
+    stub(chrome.runtime, "sendMessage", async (message) => {
+      if (message.handler == "filterCompletions") {
+        isUserSearchEngineEscaped = message.isUserSearchEngineEscaped;
+        return new Promise(() => {});
+      }
+      if (message.handler == "launchSearchQuery") launchedSearchQuery = message.query;
+    });
+
+    ui.setQuery("e ");
+    ui.onInput();
+    assert.equal("", ui.input.value);
+    await ui.onKeyEvent(newKeyEvent({ key: "Backspace" }));
+    assert.equal("e ", ui.input.value);
+    assert.isTrue(isUserSearchEngineEscaped);
+    ui.input.value += "hello";
+    ui.onInput();
+    assert.equal("e hello", ui.input.value);
+    ui.setQuery("e");
+    ui.onInput();
+    ui.setQuery("e ");
+    ui.onInput();
+    assert.equal("", ui.input.value);
+    const engine = userSearchEngines.keywordToEngine.e;
+    ui.completions = [{ isCustomSearch: true, isPrimarySuggestion: true, searchUrl: engine.url }];
+    ui.selection = 0;
+    await ui.onKeyEvent(newKeyEvent({ key: "Backspace" }));
+    await ui.onKeyEvent(newKeyEvent({ type: "keypress", key: "Enter" }));
+    ui.onHidden();
+    assert.equal("e", launchedSearchQuery);
+  });
+
   should("create command suggestions with correct HTML for key bindings", async () => {
     await Commands.loadKeyMappings("");
     const multiCompleter = new MultiCompleter([new CommandCompleter()]);