0.0.3 • Published 6 years ago
type-safe-jest-spy v0.0.3
typeSafeJestSpy
A very thin layer that helps you write faster spies by automatically inferring the real implementation's type signature
Why would you use this?
- Have you ever made a spy for entirely the wrong function?
- Have you ever returned bad data from a spy by accident?
- i.e. you knew that the method you were replacing was supposed to return a string... but you accidentally returned a number?
Who would want false-positive unit tests? Accidental mistakes with spies are a thing of the past with typeSafeJestSpy! :)
How do you use this?
- Please see the unit tests in the test folder for usage examples
Simply send your Jest spy into a function of this library and then the following Jest spy functions will require you to return the correct type:
mockImplementation
mockImplementationOnce
mockResolvedValue
mockResolvedValueOnce
Caveats
Please see the version of Jest in my package.json to see what this micro-library thinks is the way that Jest behaves. If your version of Jest is wildly different, then
- you might get irregular behavior.
- you might find that Jest has introduced a type-safe version itself, in which case this library would no longer be required