In all versions after 0.5.0 if somewhere in the code the RegExp.test is used on mocked object property then tests fails.
This can be simply reproduced using bellow test snipped, by e.g. putting it in packages/testing/ts-jest/src/mocks.spec.ts.
it('should work with RegExp', () => {
type SimpleType = {
field: string;
};
const mock = createMock<SimpleType>();
expect(/test/.test(mock.field));
});