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Testing PDF Destination Comparison Utilities in Mozilla pdf.js

This test suite validates PDF destination hash and array comparison functionality in Mozilla’s pdf.js library. It focuses on testing utilities that compare PDF navigation destinations and ensure proper handling of various destination formats.

Test Coverage Overview

The test suite provides comprehensive coverage for two key utility functions: isDestHashesEqual and isDestArraysEqual.

Tests hash comparison with various formats including page numbers, named destinations, and zoom parameters
Validates array destination comparison with different page numbers, coordinates, and zoom levels
Covers edge cases including null values and malformed inputs
Tests integration with PDF navigation and linking features

Implementation Analysis

The implementation uses Jasmine’s BDD testing framework with nested describe blocks for organized test grouping.

The testing approach employs expect() assertions to validate equality comparisons, with separate test cases for positive and negative scenarios. Each function is tested independently with carefully constructed test data representing real-world PDF destination formats.

Technical Details

Testing Framework: Jasmine
Test Structure: BDD-style describe/it blocks
Assertion Method: expect().toEqual()
Test Data: Mixed format PDF destinations including hashes and arrays
Import Testing: Module import verification from pdf_history.js

Best Practices Demonstrated

The test suite exemplifies several testing best practices including clear test organization, comprehensive edge case coverage, and isolated function testing.

Separate positive and negative test cases
Descriptive test names that explain the test purpose
Consistent test data structure
Proper test isolation and setup

mozilla/pdfJs

test/unit/pdf_history_spec.js

            
/* Copyright 2017 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 { isDestArraysEqual, isDestHashesEqual } from "../../web/pdf_history.js";

describe("pdf_history", function () {
  describe("isDestHashesEqual", function () {
    it("should reject non-equal destination hashes", function () {
      expect(isDestHashesEqual(null, "page.157")).toEqual(false);
      expect(isDestHashesEqual("title.0", "page.157")).toEqual(false);
      expect(isDestHashesEqual("page=1&zoom=auto", "page.157")).toEqual(false);

      expect(isDestHashesEqual("nameddest-page.157", "page.157")).toEqual(
        false
      );
      expect(isDestHashesEqual("page.157", "nameddest=page.157")).toEqual(
        false
      );

      const destArrayString = JSON.stringify([
        { num: 3757, gen: 0 },
        { name: "XYZ" },
        92.918,
        748.972,
        null,
      ]);
      expect(isDestHashesEqual(destArrayString, "page.157")).toEqual(false);
      expect(isDestHashesEqual("page.157", destArrayString)).toEqual(false);
    });

    it("should accept equal destination hashes", function () {
      expect(isDestHashesEqual("page.157", "page.157")).toEqual(true);
      expect(isDestHashesEqual("nameddest=page.157", "page.157")).toEqual(true);

      expect(
        isDestHashesEqual("nameddest=page.157&zoom=100", "page.157")
      ).toEqual(true);
    });
  });

  describe("isDestArraysEqual", function () {
    const firstDest = [{ num: 1, gen: 0 }, { name: "XYZ" }, 0, 375, null];
    const secondDest = [{ num: 5, gen: 0 }, { name: "XYZ" }, 0, 375, null];
    const thirdDest = [{ num: 1, gen: 0 }, { name: "XYZ" }, 750, 0, null];
    const fourthDest = [{ num: 1, gen: 0 }, { name: "XYZ" }, 0, 375, 1.0];
    const fifthDest = [{ gen: 0, num: 1 }, { name: "XYZ" }, 0, 375, null];

    it("should reject non-equal destination arrays", function () {
      expect(isDestArraysEqual(firstDest, undefined)).toEqual(false);
      expect(isDestArraysEqual(firstDest, [1, 2, 3, 4, 5])).toEqual(false);

      expect(isDestArraysEqual(firstDest, secondDest)).toEqual(false);
      expect(isDestArraysEqual(firstDest, thirdDest)).toEqual(false);
      expect(isDestArraysEqual(firstDest, fourthDest)).toEqual(false);
    });

    it("should accept equal destination arrays", function () {
      expect(isDestArraysEqual(firstDest, firstDest)).toEqual(true);
      expect(isDestArraysEqual(firstDest, fifthDest)).toEqual(true);

      const firstDestCopy = firstDest.slice();
      expect(firstDest).not.toBe(firstDestCopy);

      expect(isDestArraysEqual(firstDest, firstDestCopy)).toEqual(true);
    });
  });
});