How to use the @rxweb/reactive-form-validators.RxwebValidators.minDate function in @rxweb/reactive-form-validators

() => {
          let formBuilder = new FormBuilder();
          let formGroup = formBuilder.group({
            'enrollmentDate': '08/31/2018',
            'lastRegistrationDate': '08/31/2018'
          });
          expect(RxwebValidators.minDate({ fieldName:'enrollmentDate' })(formGroup.controls.lastRegistrationDate)).toBeNull(); 
        });

ngOnInit() {
        this.userFormGroup = this.formBuilder.group({
            userName:['',], 
            admissionDate:['', RxwebValidators.minDate({value:new Date(2018,7,30)  ,conditionalExpression:'x => x.userName == "Bharat"' })], 
            birthDate:['', RxwebValidators.minDate({value:new Date(2018,7,30)  ,conditionalExpression:(x,y) => x.userName == "Bharat"  })], 
        });
    }
}

ngOnInit() {
        this.userFormGroup = this.formBuilder.group({
            userName:['',], 
            admissionDate:['', RxwebValidators.minDate({value:new Date(2018,7,30)  ,conditionalExpression:'x => x.userName == "Bharat"' })], 
            birthDate:['', RxwebValidators.minDate({value:new Date(2018,7,30)  ,conditionalExpression:(x,y) => x.userName == "Bharat"  })], 
        });
    }
}

ngOnInit() {
        this.userFormGroup = this.formBuilder.group({
            registrationDate:['', RxwebValidators.minDate({value:new Date(2018,7,30) })], 
        });
    }
}

ngOnInit() {
        this.userFormGroup = this.formBuilder.group({
            confirmationDate:['', RxwebValidators.minDate({value:'07/30/2018'  ,operator:'>' })], 
        });
    }
}

ngOnInit() {
        this.userFormGroup = this.formBuilder.group({
            userName:['',], 
            birthDate:['', RxwebValidators.minDate({value:new Date(2018,7,30)  ,conditionalExpression:(x,y) => x.userName == "Bharat"  })], 
            admissionDate:['', RxwebValidators.minDate({value:new Date(2018,7,30)  ,conditionalExpression:'x => x.userName == "Bharat"' })], 
            registrationDate:['', RxwebValidators.minDate({value:new Date(2018,7,30)  ,message:'{{0}} exceeds the Minimum Date Limit' })], 
        });
    }
}

ngOnInit() {
        this.userFormGroup = this.formBuilder.group({
            userName:['',], 
            admissionDate:['', RxwebValidators.minDate({value:new Date(2018,7,30)  ,conditionalExpression:'x => x.userName == "Bharat"' })], 
            birthDate:['', RxwebValidators.minDate({value:new Date(2018,7,30)  ,conditionalExpression:(x,y) => x.userName == "Bharat"  })], 
        });
    }
}

ngOnInit() {
        this.userFormGroup = this.formBuilder.group({
            enrollmentDate:['',], 
            lastRegistrationDate:['', RxwebValidators.minDate({fieldName:'enrollmentDate' })], 
        });
    }
}

ngOnInit() {
        this.userFormGroup = this.formBuilder.group({
            userName:['',], 
            admissionDate:['', RxwebValidators.minDate({value:new Date(2018,7,30)  ,conditionalExpression:'x => x.userName == "Bharat"' })], 
            birthDate:['', RxwebValidators.minDate({value:new Date(2018,7,30)  ,conditionalExpression:(x,y) => x.userName == "Bharat"  })], 
        });
    }
}

ngOnInit() {
        this.userFormGroup = this.formBuilder.group({
            registrationDate:['', RxwebValidators.minDate({value:new Date(2018,7,30)  ,message:'{{0}} exceeds the Minimum Date Limit' })], 
        });
    }
}