Index match problem: Problem solving with Jest & Javascript

My solution to a “Daily Coding Problem” that I received in my mail today.

A fixed point in an array is an element whose value is equal to its index. Given a sorted array of distinct elements, return a fixed point, if one exists. Otherwise, return False.

For example, given [-6, 0, 2, 40], you should return 2. Given [1, 5, 7, 8], you should return False.

Problem solving with Jest & Javascript

function indexMatch(arr) {
    if(arr == null || arr == undefined) {
        return false;
    }
    for(var i=0; i < arr.length; i++) {
        if( i == arr[i]) {
            return i;
        }
    }
    return false;
}

module.exports = {
    indexMatch: indexMatch
};

And here’s the corresponding tests for it using JEST

const indexMatchModule = require('./indexMatch');

describe("indexMatch function", () => {
    test("Testing to see if we get 2 from [-6, 0, 2, 40]", () => {
        let harness1 = [-6, 0, 2, 40];
        expect(indexMatchModule.indexMatch(harness1)).toBe(2);
    });
    test("We don't expect to find anything from [1, 5, 7, 8]", () => {
        let harness2 = [1, 5, 7, 8];
        expect(indexMatchModule.indexMatch(harness2)).toBe(false);
    });
    test("Doing a null test", () => {
        expect(indexMatchModule.indexMatch(null)).toBe(false);
    });
    test("Doing a undefined test", () => {
        expect(indexMatchModule.indexMatch(undefined)).toBe(false);
    });
});

You can find the source code for all this along with the node project on Github.

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