Add a unit-test to check that the *official* PDF.js-viewer API exposes the expected functionality

Until now we've not actually had *any* tests that ensure that the *official* PDF.js-viewer API exposes the intended functionality, which means that things can easily break accidentally.

*Please note:* This unit-test cannot (easily) be run in Node.js-environments, since the `external/webL10n/l10n.js` file contains various browser-specific functionality.

test/unit/jasmine-boot.js

@@ -78,6 +78,7 @@ async function initializePDFJS(callback) {
       "pdfjs-test/unit/pdf_find_utils_spec.js",
       "pdfjs-test/unit/pdf_history_spec.js",
       "pdfjs-test/unit/pdf_spec.js",
+      "pdfjs-test/unit/pdf_viewer.component_spec.js",
       "pdfjs-test/unit/pdf_viewer_spec.js",
       "pdfjs-test/unit/primitives_spec.js",
       "pdfjs-test/unit/scripting_spec.js",

test/unit/pdf_viewer.component_spec.js

@@ -0,0 +1,74 @@
+/* Copyright 2023 Mozilla Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import {
+  LinkTarget,
+  PDFLinkService,
+  SimpleLinkService,
+} from "../../web/pdf_link_service.js";
+import {
+  parseQueryString,
+  ProgressBar,
+  RenderingStates,
+  ScrollMode,
+  SpreadMode,
+} from "../../web/ui_utils.js";
+import { AnnotationLayerBuilder } from "../../web/annotation_layer_builder.js";
+import { DownloadManager } from "../../web/download_manager.js";
+import { EventBus } from "../../web/event_utils.js";
+import { GenericL10n } from "../../web/genericl10n.js";
+import { NullL10n } from "../../web/l10n_utils.js";
+import { PDFFindController } from "../../web/pdf_find_controller.js";
+import { PDFHistory } from "../../web/pdf_history.js";
+import { PDFPageView } from "../../web/pdf_page_view.js";
+import { PDFScriptingManager } from "../../web/pdf_scripting_manager.js";
+import { PDFSinglePageViewer } from "../../web/pdf_single_page_viewer.js";
+import { PDFViewer } from "../../web/pdf_viewer.js";
+import { StructTreeLayerBuilder } from "../../web/struct_tree_layer_builder.js";
+import { TextLayerBuilder } from "../../web/text_layer_builder.js";
+import { XfaLayerBuilder } from "../../web/xfa_layer_builder.js";
+
+describe("pdfviewer_api", function () {
+  it("checks that the *official* PDF.js-viewer API exposes the expected functionality", async function () {
+    const pdfviewerAPI = await import("../../web/pdf_viewer.component.js");
+
+    // The imported Object contains an (automatically) inserted Symbol,
+    // hence we copy the data to allow using a simple comparison below.
+    expect({ ...pdfviewerAPI }).toEqual({
+      AnnotationLayerBuilder,
+      DownloadManager,
+      EventBus,
+      GenericL10n,
+      LinkTarget,
+      NullL10n,
+      parseQueryString,
+      PDFFindController,
+      PDFHistory,
+      PDFLinkService,
+      PDFPageView,
+      PDFScriptingManager,
+      PDFSinglePageViewer,
+      PDFViewer,
+      ProgressBar,
+      RenderingStates,
+      ScrollMode,
+      SimpleLinkService,
+      SpreadMode,
+      StructTreeLayerBuilder,
+      TextLayerBuilder,
+      XfaLayerBuilder,
+    });
+  });
+});

web/pdf_viewer.component.js

@@ -40,10 +40,12 @@ import { StructTreeLayerBuilder } from "./struct_tree_layer_builder.js";
 import { TextLayerBuilder } from "./text_layer_builder.js";
 import { XfaLayerBuilder } from "./xfa_layer_builder.js";
 
-// eslint-disable-next-line no-unused-vars
+/* eslint-disable-next-line no-unused-vars */
-const pdfjsVersion = PDFJSDev.eval("BUNDLE_VERSION");
+const pdfjsVersion =
-// eslint-disable-next-line no-unused-vars
+  typeof PDFJSDev !== "undefined" ? PDFJSDev.eval("BUNDLE_VERSION") : void 0;
-const pdfjsBuild = PDFJSDev.eval("BUNDLE_BUILD");
+/* eslint-disable-next-line no-unused-vars */
+const pdfjsBuild =
+  typeof PDFJSDev !== "undefined" ? PDFJSDev.eval("BUNDLE_BUILD") : void 0;
 
 export {
   AnnotationLayerBuilder,