tridactyl/src/mod.test.ts

/** Some real tests for mod and also an example of how to unit test. */

import {euclid_mod, knuth_mod, my_mod} from './number.mod'

expect.extend({
    /** Expect equal to all values in array */
    toBeAll(received, values:Array<any>) {
        for (let val of values) {
            if (received !== val) {
                return {
                    message: () => `expected ${received} === for each v in ${values}`,
                    pass: false
                }
            }
        }
        return {
            message: () => `expected ${received} !== for some v in ${values}`,
            pass: true
        }
    }
})

/** Manually written tests */
const testcases = [
    [-3, 3, 0],
    [-2, 3, 1],
    [-1, 3, 2],
    [0, 3, 0],
    [1, 3, 1],
    [2, 3, 2],
    [3, 3, 0],
    [4, 3, 1],
    [5, 3, 2],
    [6, 3, 0],
]

for (let [a, b, ans] of testcases) {
    test(`${a} (mod ${b}) -- .mod`, ()=>expect(a.mod(b)).toEqual(ans))
    test(`${a} (mod ${b}) -- euclid`, ()=>expect(euclid_mod(a, b)).toEqual(ans))
    test(`${a} (mod ${b}) -- knuth`, ()=>expect(knuth_mod(a, b)).toEqual(ans))
    test(`${a} (mod ${b}) -- my`, ()=>expect(my_mod(a, b)).toEqual(ans))
}


/** Test with mixed dividend, positive divisor */
for (let i=0; i<1000; i++) {
    let a = (Math.random()-0.5) * 10000|0
    let b = Math.random() * 10000|0
    b = b === 0 ? 17 : b // Don't be 0.
    test(`${a} (mod ${b}) -- equivalence check`, () => expect(a.mod(b)).toBeAll([
        my_mod(a,b),
        euclid_mod(a,b),
        knuth_mod(a,b),
    ]))
}

/** Test with a mix of +ve and -ve */
for (let i=0; i<1000; i++) {
    let a = (Math.random()-0.5) * 10000|0
    let b = (Math.random()-0.5) * 10000|0
    b = b === 0 ? 17 : b // Don't be 0.
    test(`${a} (mod ${b}) -- equivalence check`, () => expect(a.mod(b)).toBeAll([
        my_mod(a,b),
        knuth_mod(a,b),
    ]))
}