The function signature for toHaveBeenCalledWith unfortunately breaks if a generic function that consists of overloads is passed. TypeScript is not able to infer the proper overload for functions through generics. Only a single overload signature is considered for parameter inferring. For example:

function hello(idx: number): void;
function hello(item: object): void;
function hello(arg: any): void { /* impl */}

// This won't work because `MatchableArgs` only infers `object` as parameter type.
expect(hello).toHaveBeenCalledWith(1);

This is a known limitation in TypeScript, but it feels inconvenient that workarounds are needed for function overloads. Overloads are not a rare concept seen in TypeScript projects. I'm wondering if it would make sense to go back to the non-inferred parameter types. i.e. simply using any[].

Authors: @zvirja @djungowski @kolodny