fix: respect prototypes when mocking

[npdev453]

If trying to mock class instance (object with prototype) nothing working.

1. overrides totaly ignored (fixed by hasOwnProperty)
2. result object miss his proto after "cloning"

class InjectableClass {
    fn1() {
        return 'a';
    }
    fn2() {
        return 'b';
    }
}

void t.test('Encoder', (t) => {
    const mockedInjectableInstance = t.createMock(new InjectableClass(), {
        fn1() {
            return '123457';
        },
    });
})

mockedInjectableInstance will:

 {}

Instead:

 {
    fn1: () => '123457';
    __proto__: InjectableClass
}

[isaacs]

Hm, I can see how this would make t.createMock() more generally useful. I've been using it just to override imports, like:

import * as FS from 'node:fs'
await t.mockImport('../src/some-file.js', {
  fs: t.createMock(FS, {
    symlinkSync: mockSymlinkSync,
  }
})

But the name does imply that you can use it for mocking any random object, so that makes sense.

Needs some tests added to src/mock/test/index.ts to show the changed functionality. (Something that fails without the patch, passes with the patch, and brings coverage to 100%.)

[leonardoadame]

793c1c0