pdfkit/tests/unit/line_wrapper.spec.js

import PDFDocument from "../../lib/document";
import LineWrapper from '../../lib/line_wrapper';

describe("LineWrapper", () => {
  let document;

  beforeEach(() => {
    document = new PDFDocument({
      compress: false,
      margin: 0,
    });
  });

  test("ellipsis is present only on last line of multiline text", () => {
    // There is a weird edge case where ellipsis occurs on lines
    // in the middle of text due to number rounding errors
    //
    // There is probably a simpler combination of values but this is one I found in the wild
    document.y = 402.1999999999999;
    document.fontSize(7.26643598615917)
    const wrapper = new LineWrapper(document, {width: 300, height: 50.399999999999864, ellipsis: true})
    let wrapperOutput = "";
    wrapper.on("line", (buffer) => {
      wrapperOutput += buffer;
      document.y += document.currentLineHeight(true)
    })
    wrapper.wrap("- A\n- B\n- C\n- D\n- E\n- F", {})
    expect(wrapperOutput).toBe("- A\n- B\n- C\n- D\n- E\n- F");
  })

  test("line break is handled correctly when at weird heights", () => {
    // There is probably a simpler combination of values but this is one I found in the wild
    document.y = 1/3;
    document.fontSize(Math.fround(42.3/3));
    let lineHeight = document.currentLineHeight(true);
    const wrapper = new LineWrapper(document, {width: 300, height:lineHeight*3})
    let wrapperOutput = "";
    wrapper.on("line", (buffer) => {
      wrapperOutput += buffer;
      document.y += lineHeight
    })
    // Limit to 3/4 lines
    wrapper.wrap("A\nB\nC\nD", {})
    expect(wrapperOutput).toBe("A\nB\nC\n");
  });

  test("line break is handled correctly with ellipsis", () => {
    // There is probably a simpler combination of values but this is one I found in the wild
    document.y = 1/3;
    document.fontSize(Math.fround(42.3/3));
    let lineHeight = document.currentLineHeight(true);
    const wrapper = new LineWrapper(document, {width: 300, height:lineHeight*3, ellipsis: true})
    let wrapperOutput = "";
    wrapper.on("line", (buffer) => {
      wrapperOutput += buffer;
      document.y += lineHeight
    })
    // Limit to 3/4 lines
    wrapper.wrap("A\nB\nC\nD", {})
    expect(wrapperOutput).toBe("A\nB\nC…");
  });
});