Getting a "Future Warning" when importing for Yahoo with Pandas-Datareader
Cause: The cause of this warning is that, basically, the pandas_datareader is importing a module from the pandas library that will be deprecated. Specifically, it is importing pandas.util.testing whereas the new preferred module will be pandas.testing.
Solution: First off this is a warning, and not an outright error, so it won't necessarily break your program. So depending on your exact use case, you may be able to ignore it for now.
That being said, there are a few options you can consider:

Option 1: Change the code yourself -- Go into the pandas_datareader module and modify the line of code in compat_init.py that currently says from pandas.util.testing import assert_frame_equal simply to from pandas.testing import assert_frame_equal. This will import the same function from the correct module.
Option 2: Wait for pandas-datareader to update --You can also wait for the library to be upgraded to import correctly and then run pip3 install --upgrade pandas-datareader. You can go to the Github repo for pandas-datareader and raise an issue.
Option 3: Ignore it -- Just ignore the warning for now since it doesn't break your program.
I am currently , successfully, importing stock information from Yahoo using pandas-datareader. However, before the extracted data, I always get the following message: 

FutureWarning: pandas.util.testing is deprecated. Use the functions in the public API at pandas.testing instead.

Would anyone have an idea of what it means and how to fix it?