What is the good test to tell whether the fruit or vegetable is not poisonous of the Swiss family robinsin?

In "The Swiss Family Robinson," a practical test to determine if a fruit or vegetable is not poisonous is to observe animals. If local wildlife, such as birds or other creatures, consume the fruit without adverse effects, it is likely safe for humans. Additionally, the family often employs a cautious approach by trying a small amount first and waiting to see if there are any negative reactions. This method emphasizes careful observation and gradual testing to ensure safety.