Vitest template literal support for it.each

Readme.md

Used to convert jest's Tagged Template literals to object arrays as required by vitest. Example: Jest code

it.each`
str       | expected
${'1d'}   | ${moment.duration(1, 'd')}
${'2w'}   | ${moment.duration(2, 'w')}
`('should parse $str to $expected duration', ({ str, expected }) => {
   expect(yourFunction(str)).toEqual(expected);
 });

Vitest code

it.each(convert`
str       | expected
${'1d'}   | ${moment.duration(1, 'd')}
${'2w'}   | ${moment.duration(2, 'w')}
`)('should parse $str to $expected duration', ({ str, expected }) => {
   expect(yourFunction(str)).toEqual(expected);
 });

Warning

This is just a simple hack to support easy migration of jest to vitest. This was tested only on tests in Mermaid repo.

Template literal support has been avoided intentionally in Vitest, this is only meant as a stop-gap.

• vitest-dev/vitest#1521 (comment)
• vitest-dev/vitest#640 (comment)

util.ts

/*
Used to convert jest's Tagged Template literals to object arrays as required by vitest.

Example:

Jest code
```ts
it.each`
str       | expected
${'1d'}   | ${moment.duration(1, 'd')}
${'2w'}   | ${moment.duration(2, 'w')}
`('should parse $str to $expected duration', ({ str, expected }) => {
   expect(yourFunction(str)).toEqual(expected);
 });
```

Vitest code
```ts
it.each(convert`
str       | expected
${'1d'}   | ${moment.duration(1, 'd')}
${'2w'}   | ${moment.duration(2, 'w')}
`)('should parse $str to $expected duration', ({ str, expected }) => {
   expect(yourFunction(str)).toEqual(expected);
 });
```
*/

export const convert = (template: TemplateStringsArray, ...params: any[]) => {
  const header = template[0]
    .trim()
    .split('|')
    .map((s) => s.trim());
  if (header.length === 0 || params.length % header.length !== 0) {
    throw new Error('Table column count mismatch');
  }
  const chunkSize = header.length;
  const out = [];
  for (let i = 0; i < params.length; i += chunkSize) {
    const chunk = params.slice(i, i + chunkSize);
    out.push(Object.fromEntries(chunk.map((v, i) => [header[i], v])));
  }
  return out;
};