I am trying to mock a class implementing @azure/functions.Logger for unit tests in my Typescript app. The interface definition is
export interface Logger {
/**
* Writes streaming function logs at the default trace level.
*/
(...args: any[]): void;
/**
* Writes to error level logging or lower.
*/
error(...args: any[]): void;
/**
* Writes to warning level logging or lower.
*/
warn(...args: any[]): void;
/**
* Writes to info level logging or lower.
*/
info(...args: any[]): void;
/**
* Writes to verbose level logging.
*/
verbose(...args: any[]): void;
}
I try
class SuperLogger implements Logger {
error(...args: any[]): void {
console.log('jdfnjskn');
}
warn(...args: any[]): void {
throw new Error('Method not implemented.');
}
info(...args: any[]): void {
throw new Error('Method not implemented.');
}
verbose(...args: any[]): void {
throw new Error('Method not implemented.');
}
}
But it gives
Type 'SuperLogger' provides no match for the signature '(...args: any[]): void'
How do I implement the nameless function? There are some other SO answers about extending the interface, but not seeing any on a class implementing the interface.
How do I implement the nameless function?
If you're referring to the (...args: any[]): void; part of the type, that means that Logger needs to be a function. So for example:
const example: Logger = (...args: any[]) => {};
example.error = /*...*/
example.warn = /*...*/
example.info = /*...*/
example.verbose = /*...*/