Front-end Testing 101: Integration and End-to-end Testing/

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What is a Test?

What is a Test?

Learn what a test is and how it works in jest.

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Test

A test is a code that throws an error when the actual result of something does not match the expected output.

Example

Javascript (babel-node)
const sum = (a, b) => a + b;
const subtract = (a, b) => a - b;
let result, expected;
result = sum(3, 7);
expected = 10;
if (result !== expected) {
 throw new Error(`${result} is not equal to ${expected}`);
}
result = subtract(7, 3);
expected = 4;
if (result !== expected) {
  throw new Error(`${result} is not equal to ${expected}`);
}

The result !== expected part is called an assertion. You can change the variable expected to see how the assertion fails.

Jest

Jest ...