Is there a test equivalent to a bachelor's degree?
No, there is not.

A bachelor's degree isn't a generic thing like a high school diploma.  For example, it makes a big difference what institution it's from and what your major was.  Unlike high school, in the US there aren't government-specified standards for what should be taught or tested for a college degree; each institution makes its own rules (usually under the oversight of accrediting organizations).  So there's no way that a standard test could substitute for a bachelor's degree in general.

There are some reputable colleges and universities that offer online degrees, but it involves a lot more than a single test.  You'd do roughly the same coursework as if you were physically attending the university, and you should expect it to take multiple years.

There are some disreputable "colleges" which will offer a degree based on a single exam, or your life experiences.  These are scams and their degrees are worthless.