FAQ ​

Mocking Dates and Timers with Vitest ​

Vue's scheduler depends on the system time. Make sure to mount components after calling vi.setSystemTime, since Vue depends on its side effects. Mounting components before calling vi.setSystemTime may cause breaks in reactivity.

See vuejs/test-utils#2074.

Vue warn: Failed setting prop ​

[Vue warn]: Failed setting prop "prefix" on <component-stub>: value foo is invalid.
TypeError: Cannot set property prefix of #<Element> which has only a getter

[Vue warn]: Failed setting prop "prefix" on <component-stub>: value foo is invalid.
TypeError: Cannot set property prefix of #<Element> which has only a getter

This warning is shown in case you are using shallowMount or stubs with a property name that is shared with Element.

Common property names that are shared with Element:

• attributes
• children
• prefix

See: https://developer.mozilla.org/en-US/docs/Web/API/Element

Possible solutions

1. Use mount instead of shallowMount to render without stubs
2. Ignore the warning by mocking console.warn
3. Rename the prop to not clash with Element properties