What is your issue?

contributing.rst contains a link to "the testing page of the wiki" that goes instead to the main github page for xarray. The broken link is: https://github.com/pydata/xarray/wiki/Testing

Because of this, new contributors are unable to find information about "If your test requires working with files or network connectivity..."