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How can I test JavaScript code without using an additional framework such as Mocha? Is it possible to create a unit test case, write test functions manually, test the code, etc.?
I've tried to write a test case, but even though they were in the same folder, I couldn't link them.
Let's say this is a function in the main.js file
function calculate(a, b) {
return a + b;
}
And this is a test case in the testMain.js file
function testCalculate(){
if(calculate(1, 1) == 2)
console.log('It Works!');
else
console.log('Test failed');
}
testCalculate();
When I try to run testMain.js in the IntelliJ IDEA IDE I get an error similar to
"ReferenceError: calculate is not defined"
It depends whether you are trying to test Node.js code or front end code. In both cases you have to "expose" the function under test to your test framework.
Node.js
// main.js
const obj = {};
obj.sum = (a, b) => {
return a+b;
};
module.exports = obj; // Export 'obj' so that it is visible from your test runner
// test.js
const main = require('main.js');
const assert = require('assert');
const it = (desc, fn) => {
try {
fn();
console.log('\x1b[32m%s\x1b[0m', `\u2714 ${desc}`);
} catch (error) {
console.log('\n');
console.log('\x1b[31m%s\x1b[0m', `\u2718 ${desc}`);
console.error(error);
}
};
it('should return the sum of two numbers', () => {
assert.strictEqual(main.sum(5, 10), 15);
});
When you run node test.js you should be able to see the test result.
Front End
// app.js
self.myapp = myapp; // All the methods in myapp will be exposed globally
myapp.sum = function(a, b) {
return a + b;
}
// test.js
function it(desc, fn) {
try {
fn();
console.log('\x1b[32m%s\x1b[0m', '\u2714 ' + desc);
} catch (error) {
console.log('\n');
console.log('\x1b[31m%s\x1b[0m', '\u2718 ' + desc);
console.error(error);
}
}
function assert(condition) {
if (!condition) {
throw new Error();
}
}
it('should return a sum of two integers', function(){
assert(myapp.sum(5, 10) === 15);
});
// test.html - This is your test runner for the front end
<html>
...
<body>
...
<script src="app.js"></script>
<script src="test.js"></script>
</body>
</html>
Open test.html in a browser and open the browser console. You should be able to see the success message.
This way you can write test cases for Node.js and front end JavaScript code without using Mocha or any other framework.
200
answered May 02 '26 07:05
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