@Chimi_Chuang_Tzu

"How many test flights are they planning to do before sending people up in it?"

First, they will have to eventually successfully land both stages back at the launch site.

Then use that full reusability to match the partially reusable Falcon 9's launch/landing tempo (avg. every 3-4 days). Then exceed the Falcon 9's launch rate thanks to full reusability (daily launch, to multiple launches each day).

Then there will be enough data and mat'l history for a full crew version.