helpers.math.tests.js

const math = Chart.helpers;

describe('Chart.helpers.math', function() {
  var factorize = math._factorize;
  var decimalPlaces = math._decimalPlaces;

  it('should factorize', function() {
    expect(factorize(1000)).toEqual([1, 2, 4, 5, 8, 10, 20, 25, 40, 50, 100, 125, 200, 250, 500]);
    expect(factorize(60)).toEqual([1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30]);
    expect(factorize(30)).toEqual([1, 2, 3, 5, 6, 10, 15]);
    expect(factorize(24)).toEqual([1, 2, 3, 4, 6, 8, 12]);
    expect(factorize(12)).toEqual([1, 2, 3, 4, 6]);
    expect(factorize(4)).toEqual([1, 2]);
    expect(factorize(-1)).toEqual([]);
    expect(factorize(2.76)).toEqual([]);
  });

  it('should do a log10 operation', function() {
    expect(math.log10(0)).toBe(-Infinity);

    // Check all allowed powers of 10, which should return integer values
    var maxPowerOf10 = Math.floor(math.log10(Number.MAX_VALUE));
    for (var i = 0; i < maxPowerOf10; i += 1) {
      expect(math.log10(Math.pow(10, i))).toBe(i);
    }
  });

  it('should get the correct number of decimal places', function() {
    expect(decimalPlaces(100)).toBe(0);
    expect(decimalPlaces(1)).toBe(0);
    expect(decimalPlaces(0)).toBe(0);
    expect(decimalPlaces(0.01)).toBe(2);
    expect(decimalPlaces(-0.01)).toBe(2);
    expect(decimalPlaces('1')).toBe(undefined);
    expect(decimalPlaces('')).toBe(undefined);
    expect(decimalPlaces(undefined)).toBe(undefined);
    expect(decimalPlaces(12345678.1234)).toBe(4);
    expect(decimalPlaces(1234567890.1234567)).toBe(7);
  });

  it('should get an angle from a point', function() {
    var center = {
      x: 0,
      y: 0
    };

    expect(math.getAngleFromPoint(center, {
      x: 0,
      y: 10
    })).toEqual({
      angle: Math.PI / 2,
      distance: 10,
    });

    expect(math.getAngleFromPoint(center, {
      x: Math.sqrt(2),
      y: Math.sqrt(2)
    })).toEqual({
      angle: Math.PI / 4,
      distance: 2
    });

    expect(math.getAngleFromPoint(center, {
      x: -1.0 * Math.sqrt(2),
      y: -1.0 * Math.sqrt(2)
    })).toEqual({
      angle: Math.PI * 1.25,
      distance: 2
    });
  });

  it('should convert between radians and degrees', function() {
    expect(math.toRadians(180)).toBe(Math.PI);
    expect(math.toRadians(90)).toBe(0.5 * Math.PI);
    expect(math.toDegrees(Math.PI)).toBe(180);
    expect(math.toDegrees(Math.PI * 3 / 2)).toBe(270);
  });

  it('should correctly determine if two numbers are essentially equal', function() {
    expect(math.almostEquals(0, Number.EPSILON, 2 * Number.EPSILON)).toBe(true);
    expect(math.almostEquals(1, 1.1, 0.0001)).toBe(false);
    expect(math.almostEquals(1e30, 1e30 + Number.EPSILON, 0)).toBe(false);
    expect(math.almostEquals(1e30, 1e30 + Number.EPSILON, 2 * Number.EPSILON)).toBe(true);
  });

  it('should get the correct sign', function() {
    expect(math.sign(0)).toBe(0);
    expect(math.sign(10)).toBe(1);
    expect(math.sign(-5)).toBe(-1);
  });

  it('should correctly determine if a numbers are essentially whole', function() {
    expect(math.almostWhole(0.99999, 0.0001)).toBe(true);
    expect(math.almostWhole(0.9, 0.0001)).toBe(false);
    expect(math.almostWhole(1234567890123, 0.0001)).toBe(true);
    expect(math.almostWhole(1234567890123.001, 0.0001)).toBe(false);
  });

  it('should detect a number', function() {
    expect(math.isNumber(123)).toBe(true);
    expect(math.isNumber('123')).toBe(true);
    expect(math.isNumber(null)).toBe(false);
    expect(math.isNumber(NaN)).toBe(false);
    expect(math.isNumber(undefined)).toBe(false);
    expect(math.isNumber('cbc')).toBe(false);
  });

  it('should compute shortest distance between angles', function() {
    expect(math._angleDiff(1, 2)).toEqual(-1);
    expect(math._angleDiff(2, 1)).toEqual(1);
    expect(math._angleDiff(0, 3.15)).toBeCloseTo(3.13, 2);
    expect(math._angleDiff(0, 3.13)).toEqual(-3.13);
    expect(math._angleDiff(6.2, 0)).toBeCloseTo(-0.08, 2);
    expect(math._angleDiff(6.3, 0)).toBeCloseTo(0.02, 2);
    expect(math._angleDiff(4 * Math.PI, -4 * Math.PI)).toBeCloseTo(0, 4);
    expect(math._angleDiff(4 * Math.PI, -3 * Math.PI)).toBeCloseTo(-3.14, 2);
    expect(math._angleDiff(6.28, 3.1)).toBeCloseTo(-3.1, 2);
    expect(math._angleDiff(6.28, 3.2)).toBeCloseTo(3.08, 2);
  });

  it('should normalize angles correctly', function() {
    expect(math._normalizeAngle(-Math.PI)).toEqual(Math.PI);
    expect(math._normalizeAngle(Math.PI)).toEqual(Math.PI);
    expect(math._normalizeAngle(2)).toEqual(2);
    expect(math._normalizeAngle(5 * Math.PI)).toEqual(Math.PI);
    expect(math._normalizeAngle(-50 * Math.PI)).toBeCloseTo(6.28, 2);
  });

  it('should determine if angle is between boundaries', function() {
    expect(math._angleBetween(2, 1, 3)).toBeTrue();
    expect(math._angleBetween(2, 3, 1)).toBeFalse();
    expect(math._angleBetween(-3.14, 2, 4)).toBeTrue();
    expect(math._angleBetween(-3.14, 4, 2)).toBeFalse();
    expect(math._angleBetween(0, -1, 1)).toBeTrue();
    expect(math._angleBetween(-1, 0, 1)).toBeFalse();
    expect(math._angleBetween(-15 * Math.PI, 3.1, 3.2)).toBeTrue();
    expect(math._angleBetween(15 * Math.PI, -3.2, -3.1)).toBeTrue();
  });
});