import { assertEquals } from "https://deno.land/std/testing/asserts.ts";
import { always, and, never, not, or } from "./predicates.ts";

Deno.test("always", () => {
  assertEquals(always(), true);
  assertEquals(always(true), true);
  assertEquals(always(false), true);
});

Deno.test("never", () => {
  assertEquals(never(), false);
  assertEquals(never(true), false);
  assertEquals(never(false), false);
});

Deno.test("not", () => {
  const iseven = (x: number) => x % 2 == 0;
  const isodd = not(iseven);
  assertEquals(iseven(0), true);
  assertEquals(isodd(0), false);
  assertEquals(iseven(1), false);
  assertEquals(isodd(1), true);
  assertEquals(iseven(2), true);
  assertEquals(isodd(2), false);
});

Deno.test("and", () => {
  const f = and((x: number) => x % 2 == 0, (x: number) => x > 5);
  assertEquals(f(0), false);
  assertEquals(f(2), false);
  assertEquals(f(8), true);
  assertEquals(f(9), false);
  assertEquals(f(10), true);
});

Deno.test("or", () => {
  const f = or((x: number) => x % 2 == 0, (x: number) => x > 5);
  assertEquals(f(0), true);
  assertEquals(f(1), false);
  assertEquals(f(2), true);
  assertEquals(f(8), true);
  assertEquals(f(9), true);
});