47 lines
1.3 KiB
TypeScript
47 lines
1.3 KiB
TypeScript
import { expect, it } from "./deps.testing.ts";
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import { at, first, fmap, last, second, third } from "./iterables.ts";
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it("at", () => {
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const second = at(1);
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expect(second([1, 4, 8])).toBe(4);
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expect(second([1])).toBeUndefined();
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const second_from_end = at(-2);
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expect(second_from_end([1, 4, 6, 8])).toBe(6);
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expect(second_from_end([1])).toBeUndefined();
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});
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it("first", () => {
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expect(first([1, 4, 8])).toBe(1);
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expect(first([1])).toBe(1);
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expect(first([])).toBeUndefined();
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});
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it("second", () => {
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expect(second([1, 4, 8])).toBe(4);
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expect(second([1])).toBeUndefined();
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expect(second([])).toBeUndefined();
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});
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it("third", () => {
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expect(third([1, 4, 8])).toBe(8);
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expect(third([1, 4])).toBeUndefined();
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expect(third([])).toBeUndefined();
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});
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it("last", () => {
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expect(last([1, 4, 8])).toBe(8);
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expect(last([1])).toBe(1);
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expect(last([])).toBeUndefined();
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});
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it("fmap", () => {
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expect(fmap()([1, 2, 3])).toEqual([1, 2, 3]);
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expect(fmap((x: number) => x * 2)([1, 2, 3])).toEqual([2, 4, 6]);
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expect(fmap(undefined, (x: number) => x % 2 == 0)([1, 2, 3])).toEqual([2]);
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expect(fmap((x: number) => x * 2)([1, 2, 3])).toEqual([2, 4, 6]);
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expect(fmap((x: number) => x * 2, (x: number) => x < 5)([1, 2, 3])).toEqual(
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[2, 4],
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);
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});
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