https://www.lesswrong.com/posts/nTGEeRSZrfPiJwkEc/the-onion-test-for-personal-and-institutional-honesty

[co-written by Chana Messinger and Andrew Critch, Andrew is the originator of the idea]

You (or your organization or your mission or your family or etc.) pass the “onion test” for honesty if each layer hides but does not mislead about the information hidden within.

When people get to know you better, or rise higher in your organization, they may find out new things, but should not be shocked by the types of information that were hidden. If they are, you messed up in creating the outer layers to describe appropriately the kind-of-thing that might be inside. 

Examples

Positive Example: 

Outer layer says "I usually treat my health information as private."

Next layer in says: "Here are the specific health problems I have: Gout, diabetes."
 

Negative example:

Outer layer says: "I usually treat my health info as private."

Next layer in: "I operate a cocaine dealership.  Sorry I didn't warn you that I was also private about my illegal activities."