`when` and `test` stopped working together

[Sinled]

Describe the bug After migrating to yup v1.4 when and test stopped working together, worked fine in 0.32.11.

To Reproduce

Codesanbox removed ability to run tests, https://codesandbox.io/docs/learn/sandboxes/faq#where-can-i-find-the-tests-tab, so I am not sure where to add runnable test

But here simplified code and test example that worked in previous versions of yup:

Code here

```ts import { object, mixed, string } from 'yup'; import { it, expect } from 'vitest'; const schema = object().shape({ value: mixed() .label('Value') .required() .when('$model.isStringValueType', { is: true, then: () => string().required(), }) .test('is-unique-value', 'Value should be unique', function (newValue) { if (!newValue) { return true; } const values = this.parent.siblingValues.filter(({ otherValue }: { otherValue: string | number }) => { return otherValue === newValue; }); return values.length === 1; }), }); it('should be invalid if "when" is not entered', async () => { await expect( schema.isValid( { siblingValues: [{ otherValue: 'foo' }, { otherValue: 'foo' }], value: 'foo', }, { context: { model: { isStringValueType: false } } }, ), ).resolves.toBe(false); }); it('should be invalid if not a string', async () => { await expect( schema.isValid( { siblingValues: [{ otherValue: 'foo' }], value: 1, }, { context: { model: { isStringValueType: true } } }, ), ).resolves.toBe(false); }); it('should be invalid if "when" is entered and has similar siblings', async () => { await expect( schema.isValid( { siblingValues: [{ otherValue: 'foo' }, { otherValue: 'foo' }], value: 'foo', }, { context: { model: { isStringValueType: true } } }, ), ).resolves.toBe(false); }); ```

At the moment, 2nd and 3rd test fails.

Expected behavior tests should pass, both .when and .test branches should be checked

Platform (please complete the following information):

• Browser agnostic

Additional context This is recreation of https://github.com/jquense/yup/issues/2179

[jquense]

This is happening because your when is discarding the current schema and returning a fresh one without your custom test:

.when('$model.isStringValueType', {
    is: true,
-    then: () => string().required(),
+    then: schema => schema.required(),
})

[Sinled]

@jquense thanks for reply, but what should I do if I need to return different schemas? e.g. string or number depending on condition?

It worked fine before, it is not very clear what to do now.

[jquense]

Switching types isn't really supported, it didn't work fine before, it was very inconsistent and often produced broken schema which is why it was removed. You are welcome to return a brand new schema still, but it won't be automatically concated with the old one. You can approximate the old behavior by doing the concat yourself, schema=> schema.concat(string().whatever())