tesseract.js/tests/recognize.test.js

const { TesseractWorker } = Tesseract;

const isBrowser = typeof window !== 'undefined' && typeof window.document !== 'undefined';
const IMAGE_PATH = 'http://localhost:3000/tests/assets/images';
const SIMPLE_TEXT = 'Tesseract.js\n';
const COMSIC_TEXT = 'HellO World\nfrom beyond\nthe Cosmic Void\n';
const TESTOCR_TEXT = 'This is a lot of 12 point text to test the\nocr code and see if it works on all types\nof file format.\n\nThe quick brown dog jumped over the\nlazy fox. The quick brown dog jumped\nover the lazy fox. The quick brown dog\njumped over the lazy fox. The quick\nbrown dog jumped over the lazy fox.\n';
const CHINESE_TEXT = '繁 體 中 文 測 試\n';
const FORMATS = ['png', 'jpg', 'bmp', 'pbm'];

const loadLangOptions = {
  langPath: 'http://localhost:3000/tests/assets/traineddata',
  cachePath: './tests/assets/traineddata',
};

const getWorker = options => (
  new TesseractWorker({
    cacheMethod: 'readOnly',
    ...(isBrowser ? { workerPath: 'http://localhost:3000/dist/worker.dev.js' } : {}),
    ...loadLangOptions,
    ...options,
  })
);

describe('recognize()', () => {
  describe('should recognize different langs', () => {
    [
      { name: 'chinese.png', lang: 'chi_tra', ans: CHINESE_TEXT },
    ].forEach(({ name, lang, ans }) => (
      it(`recongize ${lang}`, (done) => {
        const worker = getWorker();
        worker
          .recognize(`${IMAGE_PATH}/${name}`, lang)
          .then(({ text }) => {
            expect(text).to.be(ans);
            worker.terminate();
            done();
          });
      }).timeout(30000)
    ));
  });

  describe('should read bmp, jpg, png and pbm format images', () => {
    FORMATS.forEach(format => (
      it(`support ${format} format`, (done) => {
        const worker = getWorker();
        worker
          .recognize(`${IMAGE_PATH}/simple.${format}`)
          .then(({ text }) => {
            expect(text).to.be(SIMPLE_TEXT);
            worker.terminate();
            done();
          });
      }).timeout(10000)
    ));
  });

  describe('should be able to recognize multiple images with 1 worker', () => {
    [3, 10, 20].forEach(num => (
      it(`recognize ${num} images with 1 worker`, (done) => {
        const worker = getWorker();
        Promise.all(
          Array(num).fill(0).map(() => worker.recognize(`${IMAGE_PATH}/simple.png`)),
        ).then((results) => {
          results.forEach(({ text }) => {
            expect(text).to.be(SIMPLE_TEXT);
          });
          worker.terminate();
          done();
        });
      }).timeout(60000)
    ));
  });

  describe('should recognize multiple images in order', () => {
    [1, 2].forEach((num) => {
      it(`recognize ${num * 2} images with 1 worker in order`, (done) => {
        const worker = getWorker();
        const cases = Array(num).fill(0)
          .reduce(acc => (
            acc.concat([
              { name: 'simple.png', ans: SIMPLE_TEXT },
              { name: 'cosmic.png', ans: COMSIC_TEXT },
            ])
          ),
          []);
        Promise.all(
          cases.map(({ name }) => worker.recognize(`${IMAGE_PATH}/${name}`)),
        ).then((results) => {
          results.forEach(({ text }, idx) => {
            expect(text).to.be(cases[idx].ans);
          });
          worker.terminate();
          done();
        });
      }).timeout(30000);
    });
  });

  describe('supports different complexity', () => {
    [
      { name: 'simple.png', desc: 'simple', ans: SIMPLE_TEXT },
      { name: 'cosmic.png', desc: 'normal', ans: COMSIC_TEXT },
      { name: 'testocr.png', desc: 'complex', ans: TESTOCR_TEXT },
    ].forEach(({ name, desc, ans }) => (
      it(`recongize ${desc} image`, (done) => {
        const worker = getWorker();
        worker
          .recognize(`${IMAGE_PATH}/${name}`)
          .then(({ text }) => {
            expect(text).to.be(ans);
            worker.terminate();
            done();
          });
      }).timeout(60000)
    ));
  });

  (isBrowser ? describe : describe.skip)('should read image from img DOM element (browser only)', () => {
    FORMATS.forEach(format => (
      it(`support ${format} format`, (done) => {
        const imageDOM = document.createElement('img');
        imageDOM.setAttribute('src', `${IMAGE_PATH}/simple.${format}`);
        const worker = getWorker();
        worker
          .recognize(imageDOM)
          .then(({ text }) => {
            expect(text).to.be(SIMPLE_TEXT);
            worker.terminate();
            imageDOM.remove();
            done();
          });
      }).timeout(10000)
    ));
  });
  
  (isBrowser ? describe : describe.skip)('should read image from video DOM element (browser only)', () => {
    FORMATS.forEach(format => (
      it(`support ${format} format`, (done) => {
        const videoDOM = document.createElement('video');
        videoDOM.setAttribute('poster', `${IMAGE_PATH}/simple.${format}`);
        const worker = getWorker();
        worker
          .recognize(videoDOM)
          .then(({ text }) => {
            expect(text).to.be(SIMPLE_TEXT);
            worker.terminate();
            videoDOM.remove();
            done();
          });
      }).timeout(10000)
    ));
  });

  (isBrowser ? describe : describe.skip)('should read video from canvas DOM element (browser only)', () => {
    /*
     * img tag is unable to render pbm, so let's skip it.
     */
    const formats = FORMATS.filter(f => f !== 'pbm');
    let canvasDOM = null;
    let imageDOM = null;
    let idx = 0;
    beforeEach((done) => {
      canvasDOM = document.createElement('canvas');
      imageDOM = document.createElement('img');
      imageDOM.setAttribute('crossOrigin', 'Anonymous');
      imageDOM.onload = () => {
        canvasDOM.getContext('2d').drawImage(imageDOM, 0, 0);
        done();
      };
      imageDOM.setAttribute('src', `${IMAGE_PATH}/simple.${formats[idx]}`);
      idx += 1;
    });

    afterEach(() => {
      canvasDOM.remove();
      imageDOM.remove();
    });

    formats.forEach(format => (
      it(`support ${format} format`, (done) => {
        const worker = getWorker();
        worker
          .recognize(canvasDOM)
          .then(({ text }) => {
            expect(text).to.be(SIMPLE_TEXT);
            worker.terminate();
            done();
          });
      }).timeout(10000)
    ));
  });
});