CODEWITHSUNDEEP
javascripttypescriptconsoledeno
Ikechukwu Eze
Ikechukwu Eze

Reputation: 3151

Read value logged to the console in Deno

How can I read a value logged to the console in Deno? I'm trying to write a test that checks if a function logs the right value to console.

I've already tried this, but it can only read values manually typed into stdin. Getting values from Deno stdin

Upvotes: 2

Views: 793

Answers (2)

Matt McClure
Matt McClure

Reputation: 2156

This is a really old question, but I stumbled across it trying to solve something similar. I ended up using Deno's built in mocking to set up a spy in a test and checking to make sure console.log was called with the expected value.

import {
  assertSpyCall,
  spy,
} from "https://deno.land/[email protected]/testing/mock.ts";

function veryImportantLogger(val: string) {
  console.log(val)
}

Deno.test("Checks to make sure the right value is logged", () => {
  const logSpy = spy(console, "log");
  const logValue = "well hello there";
  veryImportantLogger(logValue);

  assertSpyCall(logSpy, 0, {
    args: [logValue]
  });
});

Upvotes: 4

Ikechukwu Eze
Ikechukwu Eze

Reputation: 3151

This is more of a hack but works in my case

class BinarySearchTree<T> {
// ...
inOrderPrint() {
    if (this.left) {
      this.left.inOrderPrint();
    }
    console.log(this.value);
    if (this.right) {
      this.right.inOrderPrint();
    }
  }
// ...
}


test("BST: should print elements in order", () => {
  let a = [];
  const log = console.log;
  console.log = x => {
    a.push(x);
  };
  const bst = new BinarySearchTree<number>(1);
  bst.insert(8);
  bst.insert(5);
  bst.insert(7);
  bst.insert(6);
  bst.insert(3);
  bst.insert(4);
  bst.insert(2);
  bst.inOrderPrint();
  console.log = log;
  assertEquals(a.join(""), "12345678");
});

Upvotes: 1

Related Questions