This patch fixes the bug where TypeError is thrown in mockReset/mockClear when the mock has properties with null or undefined values.
I encounter this bug when using jest-mock-extended along with jest-when (https://github.com/timkindberg/jest-when/blob/master/src/when.js#L204).
jest-when internally uses __whenMock__ property to store the mock setup, and assign undefined to this once the mock is reset. Calling mockClear or mockReset after that would throw TypeError exception.
This patch fixes the bug where TypeError is thrown in
mockReset/mockClearwhen the mock has properties withnullorundefinedvalues.I encounter this bug when using
jest-mock-extendedalong withjest-when(https://github.com/timkindberg/jest-when/blob/master/src/when.js#L204).jest-wheninternally uses__whenMock__property to store the mock setup, and assignundefinedto this once the mock is reset. CallingmockClearormockResetafter that would throw TypeError exception.