CODEWITHSUNDEEP
javascriptnode.jsunit-testingjestjs
enbermudas
enbermudas

Reputation: 1615

Expect throwError not getting coverage

There is a ValidationError (custom made) being thrown on my invert function if no string is provided:

const invert = (str) => {
  if (str === '') throw new ValidationError('String must no be empty.');
  return str;
};

This line of code is not getting full coverage by my assertion while using Jest:

expect(() => invert('')).toThrow(ValidationError);

Is there a way to get coverage for this line?

Upvotes: 1

Views: 478

Answers (1)

Lin Du
Lin Du

Reputation: 102257

You should have two test cases at least. One test throws an error, and one test is normal. E.g.

index.ts:

export class ValidationError extends Error {
  constructor(message) {
    super(message);
  }
}
export const invert = (str) => {
  if (str === '') throw new ValidationError('String must no be empty.');
  return str;
};

index.test.ts:

import { invert, ValidationError } from './';

describe('64271662', () => {
  it('should throw validation error if string is empty', () => {
    expect(() => invert('')).toThrow(ValidationError);
  });
  it('should return string', () => {
    expect(invert('teresa teng')).toBe('teresa teng');
  });
});

unit test result with 100% coverage:

 PASS  src/stackoverflow/64271662/index.test.ts (9.867s)
  64271662
    ✓ should throw validation error if string is empty (4ms)
    ✓ should return string (1ms)

----------|----------|----------|----------|----------|-------------------|
File      |  % Stmts | % Branch |  % Funcs |  % Lines | Uncovered Line #s |
----------|----------|----------|----------|----------|-------------------|
All files |      100 |      100 |      100 |      100 |                   |
 index.ts |      100 |      100 |      100 |      100 |                   |
----------|----------|----------|----------|----------|-------------------|
Test Suites: 1 passed, 1 total
Tests:       2 passed, 2 total
Snapshots:   0 total
Time:        11.042s

Upvotes: 1

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