Back to Repositories

Testing Type1 Font Parser Implementation in Mozilla PDF.js

This test suite validates the Type1Parser functionality in Mozilla’s PDF.js library, focusing on parsing Type 1 fonts and their components. The tests verify token handling, number parsing, and font program extraction capabilities.

Test Coverage Overview

The test suite provides comprehensive coverage of Type1Parser functionality, including:

Token splitting and handling
Number and boolean parsing
Array processing
Font program extraction
Font header parsing
Encoding table validation

Implementation Analysis

The testing approach employs Jasmine’s describe/it pattern for structured unit testing. Tests utilize StringStream for input simulation and verify parser outputs through expect assertions. The implementation focuses on granular validation of parser components.

Technical Details

Testing Framework: Jasmine
Key Dependencies: StringStream, Type1Parser
Test Environment: Node.js
Configuration: SEAC_ANALYSIS_ENABLED flag

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Isolated test cases for specific functionality
Comprehensive edge case coverage
Clear test descriptions
Consistent assertion patterns
Modular test organization

mozilla/pdfJs

test/unit/type1_parser_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 { SEAC_ANALYSIS_ENABLED } from "../../src/core/fonts_utils.js";
import { StringStream } from "../../src/core/stream.js";
import { Type1Parser } from "../../src/core/type1_parser.js";

describe("Type1Parser", function () {
  it("splits tokens", function () {
    const stream = new StringStream("/BlueValues[-17 0]noaccess def");
    const parser = new Type1Parser(stream, false, SEAC_ANALYSIS_ENABLED);
    expect(parser.getToken()).toEqual("/");
    expect(parser.getToken()).toEqual("BlueValues");
    expect(parser.getToken()).toEqual("[");
    expect(parser.getToken()).toEqual("-17");
    expect(parser.getToken()).toEqual("0");
    expect(parser.getToken()).toEqual("]");
    expect(parser.getToken()).toEqual("noaccess");
    expect(parser.getToken()).toEqual("def");
    expect(parser.getToken()).toEqual(null);
  });

  it("handles glued tokens", function () {
    const stream = new StringStream("dup/CharStrings");
    const parser = new Type1Parser(stream, false, SEAC_ANALYSIS_ENABLED);
    expect(parser.getToken()).toEqual("dup");
    expect(parser.getToken()).toEqual("/");
    expect(parser.getToken()).toEqual("CharStrings");
  });

  it("ignores whitespace", function () {
    const stream = new StringStream("\nab   c\t");
    const parser = new Type1Parser(stream, false, SEAC_ANALYSIS_ENABLED);
    expect(parser.getToken()).toEqual("ab");
    expect(parser.getToken()).toEqual("c");
  });

  it("parses numbers", function () {
    const stream = new StringStream("123");
    const parser = new Type1Parser(stream, false, SEAC_ANALYSIS_ENABLED);
    expect(parser.readNumber()).toEqual(123);
  });

  it("parses booleans", function () {
    const stream = new StringStream("true false");
    const parser = new Type1Parser(stream, false, SEAC_ANALYSIS_ENABLED);
    expect(parser.readBoolean()).toEqual(1);
    expect(parser.readBoolean()).toEqual(0);
  });

  it("parses number arrays", function () {
    let stream = new StringStream("[1 2]");
    let parser = new Type1Parser(stream, false, SEAC_ANALYSIS_ENABLED);
    expect(parser.readNumberArray()).toEqual([1, 2]);
    // Variation on spacing.
    stream = new StringStream("[ 1 2 ]");
    parser = new Type1Parser(stream, false, SEAC_ANALYSIS_ENABLED);
    expect(parser.readNumberArray()).toEqual([1, 2]);
  });

  it("skips comments", function () {
    const stream = new StringStream(
      "%!PS-AdobeFont-1.0: CMSY10 003.002\n" +
        "%%Title: CMSY10\n" +
        "%Version: 003.002\n" +
        "FontDirectory"
    );
    const parser = new Type1Parser(stream, false, SEAC_ANALYSIS_ENABLED);
    expect(parser.getToken()).toEqual("FontDirectory");
  });

  it("parses font program", function () {
    const stream = new StringStream(
      "/ExpansionFactor  99\n" +
        "/Subrs 1 array\n" +
        "dup 0 1 RD x noaccess put\n" +
        "end\n" +
        "/CharStrings 46 dict dup begin\n" +
        "/.notdef 1 RD x ND\n" +
        "end"
    );
    const parser = new Type1Parser(stream, false, SEAC_ANALYSIS_ENABLED);
    const program = parser.extractFontProgram({});
    expect(program.charstrings.length).toEqual(1);
    expect(program.properties.privateData.ExpansionFactor).toEqual(99);
  });

  it("parses font header font matrix", function () {
    const stream = new StringStream(
      "/FontMatrix [0.001 0 0 0.001 0 0 ]readonly def\n"
    );
    const parser = new Type1Parser(stream, false, SEAC_ANALYSIS_ENABLED);
    const props = {};
    parser.extractFontHeader(props);
    expect(props.fontMatrix).toEqual([0.001, 0, 0, 0.001, 0, 0]);
  });

  it("parses font header encoding", function () {
    const stream = new StringStream(
      "/Encoding 256 array\n" +
        "0 1 255 {1 index exch /.notdef put} for\n" +
        "dup 33 /arrowright put\n" +
        "readonly def\n"
    );
    const parser = new Type1Parser(stream, false, SEAC_ANALYSIS_ENABLED);
    const props = { overridableEncoding: true };
    parser.extractFontHeader(props);
    expect(props.builtInEncoding[33]).toEqual("arrowright");
  });
});