Chart.js/test/specs/helpers.curve.tests.js

describe('Curve helper tests', function() {
  let helpers;

  beforeAll(function() {
    helpers = window.Chart.helpers;
  });

  it('should spline curves', function() {
    expect(helpers.splineCurve({
      x: 0,
      y: 0
    }, {
      x: 1,
      y: 1
    }, {
      x: 2,
      y: 0
    }, 0)).toEqual({
      previous: {
        x: 1,
        y: 1,
      },
      next: {
        x: 1,
        y: 1,
      }
    });

    expect(helpers.splineCurve({
      x: 0,
      y: 0
    }, {
      x: 1,
      y: 1
    }, {
      x: 2,
      y: 0
    }, 1)).toEqual({
      previous: {
        x: 0,
        y: 1,
      },
      next: {
        x: 2,
        y: 1,
      }
    });
  });

  it('should spline curves with monotone cubic interpolation', function() {
    var dataPoints = [
      {x: 0, y: 0, skip: false},
      {x: 3, y: 6, skip: false},
      {x: 9, y: 6, skip: false},
      {x: 12, y: 60, skip: false},
      {x: 15, y: 60, skip: false},
      {x: 18, y: 120, skip: false},
      {x: null, y: null, skip: true},
      {x: 21, y: 180, skip: false},
      {x: 24, y: 120, skip: false},
      {x: 27, y: 125, skip: false},
      {x: 30, y: 105, skip: false},
      {x: 33, y: 110, skip: false},
      {x: 33, y: 110, skip: false},
      {x: 36, y: 170, skip: false}
    ];
    helpers.splineCurveMonotone(dataPoints);
    expect(dataPoints).toEqual([{
      x: 0,
      y: 0,
      skip: false,
      controlPointNextX: 1,
      controlPointNextY: 2
    },
    {
      x: 3,
      y: 6,
      skip: false,
      controlPointPreviousX: 2,
      controlPointPreviousY: 6,
      controlPointNextX: 5,
      controlPointNextY: 6
    },
    {
      x: 9,
      y: 6,
      skip: false,
      controlPointPreviousX: 7,
      controlPointPreviousY: 6,
      controlPointNextX: 10,
      controlPointNextY: 6
    },
    {
      x: 12,
      y: 60,
      skip: false,
      controlPointPreviousX: 11,
      controlPointPreviousY: 60,
      controlPointNextX: 13,
      controlPointNextY: 60
    },
    {
      x: 15,
      y: 60,
      skip: false,
      controlPointPreviousX: 14,
      controlPointPreviousY: 60,
      controlPointNextX: 16,
      controlPointNextY: 60
    },
    {
      x: 18,
      y: 120,
      skip: false,
      controlPointPreviousX: 17,
      controlPointPreviousY: 100
    },
    {
      x: null,
      y: null,
      skip: true
    },
    {
      x: 21,
      y: 180,
      skip: false,
      controlPointNextX: 22,
      controlPointNextY: 160
    },
    {
      x: 24,
      y: 120,
      skip: false,
      controlPointPreviousX: 23,
      controlPointPreviousY: 120,
      controlPointNextX: 25,
      controlPointNextY: 120
    },
    {
      x: 27,
      y: 125,
      skip: false,
      controlPointPreviousX: 26,
      controlPointPreviousY: 125,
      controlPointNextX: 28,
      controlPointNextY: 125
    },
    {
      x: 30,
      y: 105,
      skip: false,
      controlPointPreviousX: 29,
      controlPointPreviousY: 105,
      controlPointNextX: 31,
      controlPointNextY: 105
    },
    {
      x: 33,
      y: 110,
      skip: false,
      controlPointPreviousX: 32,
      controlPointPreviousY: 110,
      controlPointNextX: 33,
      controlPointNextY: 110
    },
    {
      x: 33,
      y: 110,
      skip: false,
      controlPointPreviousX: 33,
      controlPointPreviousY: 110,
      controlPointNextX: 34,
      controlPointNextY: 110
    },
    {
      x: 36,
      y: 170,
      skip: false,
      controlPointPreviousX: 35,
      controlPointPreviousY: 150
    }]);
  });
});