javascript

Vitest spy on undefined or already spied

vitest.*cannot spy.*already.*spied|vi\.spyOn.*target.*undefined

Fixes

1.Reset spies with vi.restoreAllMocks()
2.Verify object/method exists before spy
3.Use vi.clearAllMocks() in beforeEach

vitestspymock

Related Errors

javascript3 fixes

Cannot read property of undefined

Cannot read propert(y|ies) of undefined

•Add optional chaining (?.)
•Check if object exists before accessing

javascript3 fixes

Cannot read property of null

Cannot read propert(y|ies) of null

•Add null check before access
•Use optional chaining (?.)

javascript3 fixes

TypeError: X is not a function

is not a function

•Check spelling of method name
•Verify import is correct