excalidraw/packages/math/tests/range.test.ts

import { rangeInclusive, rangeIntersection, rangesOverlap } from "../src/range";

describe("range overlap", () => {
  const range1_4 = rangeInclusive(1, 4);

  it("should overlap when range a contains range b", () => {
    expect(rangesOverlap(range1_4, rangeInclusive(2, 3))).toBe(true);
    expect(rangesOverlap(range1_4, range1_4)).toBe(true);
    expect(rangesOverlap(range1_4, rangeInclusive(1, 3))).toBe(true);
    expect(rangesOverlap(range1_4, rangeInclusive(2, 4))).toBe(true);
  });

  it("should overlap when range b contains range a", () => {
    expect(rangesOverlap(rangeInclusive(2, 3), range1_4)).toBe(true);
    expect(rangesOverlap(rangeInclusive(1, 3), range1_4)).toBe(true);
    expect(rangesOverlap(rangeInclusive(2, 4), range1_4)).toBe(true);
  });

  it("should overlap when range a and b intersect", () => {
    expect(rangesOverlap(range1_4, rangeInclusive(2, 5))).toBe(true);
  });
});

describe("range intersection", () => {
  const range1_4 = rangeInclusive(1, 4);

  it("should intersect completely with itself", () => {
    expect(rangeIntersection(range1_4, range1_4)).toEqual(range1_4);
  });

  it("should intersect irrespective of order", () => {
    expect(rangeIntersection(range1_4, rangeInclusive(2, 3))).toEqual([2, 3]);
    expect(rangeIntersection(rangeInclusive(2, 3), range1_4)).toEqual([2, 3]);
    expect(rangeIntersection(range1_4, rangeInclusive(3, 5))).toEqual(
      rangeInclusive(3, 4),
    );
    expect(rangeIntersection(rangeInclusive(3, 5), range1_4)).toEqual(
      rangeInclusive(3, 4),
    );
  });

  it("should intersect at the edge", () => {
    expect(rangeIntersection(range1_4, rangeInclusive(4, 5))).toEqual(
      rangeInclusive(4, 4),
    );
  });

  it("should not intersect", () => {
    expect(rangeIntersection(range1_4, rangeInclusive(5, 7))).toEqual(null);
  });
});