Back to Repositories

Validating PDF.js Viewer Component API Surface in Mozilla PDF.js

This test suite validates the PDF.js viewer API component, ensuring all expected functionality and modules are properly exposed. The tests verify the integrity of the public API interface and its core components for PDF rendering and interaction.

Test Coverage Overview

The test suite provides comprehensive coverage of the PDF.js viewer API surface.

Key areas tested include:

Core viewer components (PDFViewer, PDFSinglePageViewer)
Document interaction services (PDFLinkService, PDFFindController)
Layer builders (AnnotationLayer, TextLayer, XfaLayer)
Utility modules (EventBus, DownloadManager, ProgressBar)

Implementation Analysis

The testing approach uses Jest’s describe/it pattern for API surface validation. The implementation employs module imports and object comparison to verify the complete public API interface.

The test specifically checks that all expected components are properly exported and accessible through the main pdf_viewer.component.js entry point.

Technical Details

Testing tools and configuration:

Jest testing framework
ES6 module import/export syntax
Object destructuring for comparison
Symbol-aware property comparison
Async/await for module loading

Best Practices Demonstrated

The test demonstrates several quality testing practices:

Explicit API surface verification
Clean separation of concerns in test structure
Proper handling of module symbols and properties
Comprehensive component coverage
Clear test intention and documentation

mozilla/pdfJs

test/unit/pdf_viewer.component_spec.js

            
/* 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 { FindState, PDFFindController } from "../../web/pdf_find_controller.js";
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 { PDFHistory } from "../../web/pdf_history.js";
import { PDFPageView } from "../../web/pdf_page_view.js";
import { PDFScriptingManager } from "../../web/pdf_scripting_manager.component.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,
      FindState,
      GenericL10n,
      LinkTarget,
      parseQueryString,
      PDFFindController,
      PDFHistory,
      PDFLinkService,
      PDFPageView,
      PDFScriptingManager,
      PDFSinglePageViewer,
      PDFViewer,
      ProgressBar,
      RenderingStates,
      ScrollMode,
      SimpleLinkService,
      SpreadMode,
      StructTreeLayerBuilder,
      TextLayerBuilder,
      XfaLayerBuilder,
    });
  });
});