spec/query-range-spec.js

import QueryRange from '../lib/query-range';

describe("QueryRange", function QueryRangeSpecs() {
  describe("@infinite", () =>
    it("should return a query range with a null limit and offset", () => {
      const infinite = QueryRange.infinite();
      expect(infinite.limit).toBe(null);
      expect(infinite.offset).toBe(null);
    })

  );

  describe("@rangesBySubtracting", () => {
    it("should throw an exception if either range is infinite", () => {
      const infinite = QueryRange.infinite();

      expect(() =>
        QueryRange.rangesBySubtracting(infinite, new QueryRange({offset: 0, limit: 10}))
      ).toThrow();

      expect(() =>
        QueryRange.rangesBySubtracting(new QueryRange({offset: 0, limit: 10}), infinite)
      ).toThrow();
    });

    it("should return one or more ranges created by punching the provided range", () => {
      const test = ({a, b, result}) => expect(QueryRange.rangesBySubtracting(a, b)).toEqual(result);
      test({
        a: new QueryRange({offset: 0, limit: 10}),
        b: new QueryRange({offset: 3, limit: 3}),
        result: [new QueryRange({offset: 0, limit: 3}), new QueryRange({offset: 6, limit: 4})]});

      test({
        a: new QueryRange({offset: 0, limit: 10}),
        b: new QueryRange({offset: 3, limit: 10}),
        result: [new QueryRange({offset: 0, limit: 3})]});

      test({
        a: new QueryRange({offset: 0, limit: 10}),
        b: new QueryRange({offset: 0, limit: 10}),
        result: []});

      test({
        a: new QueryRange({offset: 5, limit: 10}),
        b: new QueryRange({offset: 0, limit: 4}),
        result: [new QueryRange({offset: 5, limit: 10})]});

      test({
        a: new QueryRange({offset: 5, limit: 10}),
        b: new QueryRange({offset: 0, limit: 8}),
        result: [new QueryRange({offset: 8, limit: 7})]});
    });
  });

  describe("isInfinite", () =>
    it("should return true for an infinite range, false otherwise", () => {
      const infinite = QueryRange.infinite();
      expect(infinite.isInfinite()).toBe(true);
      expect(new QueryRange({offset: 0, limit: 4}).isInfinite()).toBe(false);
    })
  );

  describe("start", () =>
    it("should be an alias for offset", () =>
      expect((new QueryRange({offset: 3, limit: 4})).start).toBe(3)
    )
  );

  describe("end", () =>
    it("should be offset + limit", () =>
      expect((new QueryRange({offset: 3, limit: 4})).end).toBe(7)
    )
  );

  describe("isContiguousWith", () => {
    it("should return true if either range is infinite", () => {
      const a = new QueryRange({offset: 3, limit: 4});
      expect(a.isContiguousWith(QueryRange.infinite())).toBe(true);
      expect(QueryRange.infinite().isContiguousWith(a)).toBe(true);
    });

    it("should return true if the ranges intersect or touch, false otherwise", () => {
      const a = new QueryRange({offset: 3, limit: 4});
      const b = new QueryRange({offset: 0, limit: 2});
      const c = new QueryRange({offset: 0, limit: 3});
      const d = new QueryRange({offset: 7, limit: 10});
      const e = new QueryRange({offset: 8, limit: 10});

      // True

      expect(a.isContiguousWith(d)).toBe(true);
      expect(d.isContiguousWith(a)).toBe(true);

      expect(a.isContiguousWith(c)).toBe(true);
      expect(c.isContiguousWith(a)).toBe(true);

      // False

      expect(a.isContiguousWith(b)).toBe(false);
      expect(b.isContiguousWith(a)).toBe(false);

      expect(a.isContiguousWith(e)).toBe(false);
      expect(e.isContiguousWith(a)).toBe(false);

      expect(b.isContiguousWith(e)).toBe(false);
      expect(e.isContiguousWith(b)).toBe(false);
    });
  });
});