source: trip-planner-front/node_modules/hdr-histogram-js/src/PackedHistogram.spec.ts

import Histogram from "./PackedHistogram";

describe("Packed histogram", () => {
  it("should compute median value in first bucket", () => {
    // given
    const histogram = new Histogram(1, Number.MAX_SAFE_INTEGER, 3);
    histogram.recordValue(123456);
    histogram.recordValue(127);
    histogram.recordValue(42);
    // when
    const medianValue = histogram.getValueAtPercentile(50);
    // then
    expect(medianValue).toBe(127);
  });

  it("should compute same values when new or reseted", () => {
    // given
    const histogram = new Histogram(1, 2, 3);
    const histogram2 = new Histogram(1, 2, 3);
    histogram.autoResize = true;
    histogram2.autoResize = true;

    [1, 49026].forEach((v) => histogram.recordValue(v));

    // when
    histogram.reset();
    [7, 67, 42357, 805017].forEach((v) => {
      histogram.recordValue(v);
      histogram2.recordValue(v);
    });
    // then
    expect(histogram.getValueAtPercentile(5)).toBe(
      histogram2.getValueAtPercentile(5)
    );
  });

  it("should compute value outside first bucket with an error less than 1000", () => {
    // given
    const histogram = new Histogram(1, 123456, 2);
    histogram.recordValue(5234);
    histogram.recordValue(127);
    histogram.recordValue(42);
    // when
    const percentileValue = histogram.getValueAtPercentile(90);
    // then
    expect(Math.abs(percentileValue - 5234)).toBeLessThan(100);
  });

  it("should resize underlying packed array when recording an out of bound value", () => {
    // given
    const histogram = new Histogram(1, 2, 3);
    histogram.autoResize = true;
    // when
    histogram.recordValue(123456);
    // then
    expect(histogram.totalCount).toBe(1);
  });
});

describe("Histogram clearing support", () => {
  it("should reset data in order to reuse histogram", () => {
    // given
    const histogram = new Histogram(1, Number.MAX_SAFE_INTEGER, 2);
    const histogram2 = new Histogram(1, Number.MAX_SAFE_INTEGER, 2);
    histogram.startTimeStampMsec = 42;
    histogram.endTimeStampMsec = 56;
    histogram.tag = "blabla";
    histogram.recordValue(10);
    histogram.recordValue(1000);
    histogram.recordValue(10000000);
    // when
    histogram.reset();
    // then
    expect(histogram.totalCount).toBe(0);
    expect(histogram.startTimeStampMsec).toBe(0);
    expect(histogram.endTimeStampMsec).toBe(0);
    //expect(histogram.tag).toBe(NO_TAG);
    expect(histogram.maxValue).toBe(0);
    expect(histogram.minNonZeroValue).toBe(Number.MAX_SAFE_INTEGER);
    expect(histogram.getValueAtPercentile(99.999)).toBe(0);
  });
});