scale-image.function.spec.ts

import * as path from "path";
import { ImageProcessor } from "./image-processor.class";
import { ImageReader } from "./image-reader.class";
import { scaleImage } from "./scale-image.function";

describe("scaleImage", () => {
  it.each([[0.5], [1.5]])("should scale an image correctly by factor %f", async (scaleFactor) => {
    // GIVEN
    const imageLoader = new ImageReader();
    const pathToinput = path.resolve(__dirname, "./__mocks__/mouse.png");
    const inputImage = await imageLoader.load(pathToinput);
    const inputMat = await ImageProcessor.fromImageWithoutAlphaChannel(inputImage);
    const expectedWidth = Math.floor(inputMat.cols * scaleFactor);
    const expectedHeight = Math.floor(inputMat.rows * scaleFactor);

    // WHEN
    const result = await scaleImage(inputMat, scaleFactor);

    // THEN
    expect(result.rows).toBe(expectedHeight);
    expect(result.cols).toBe(expectedWidth);
  });

  it.each([[0], [-0.25]])("should keep scale if factor <= 0: Scale %f", async (scaleFactor) => {
    // GIVEN
    const imageLoader = new ImageReader();
    const pathToinput = path.resolve(__dirname, "./__mocks__/mouse.png");
    const inputImage = await imageLoader.load(pathToinput);
    const inputMat = await ImageProcessor.fromImageWithoutAlphaChannel(inputImage);
    const expectedWidth = inputMat.cols;
    const expectedHeight = inputMat.rows;

    // WHEN
    const result = await scaleImage(inputMat, scaleFactor);

    // THEN
    expect(result.rows).toBe(expectedHeight);
    expect(result.cols).toBe(expectedWidth);
  });
});