Does the iPad mini warranty cover the charger?
Short Answer
Apple warrants all hardware for one year in general. Depending on where you purchased the hardware, your warranty coverage and service options may vary. If an Apple Store is convenient, make a genius bar appointment and bring your iPad, cable and charger in case the cause isn't just the adapter. If not, you can find warranty service options online: https://locate.apple.com
Explanation(Proof)
From Apple's Legal Support Page:

This Warranty does not apply: (a) to consumable parts, such as
batteries or protective coatings that are designed to diminish over
time, unless failure has occurred due to a defect in materials or
workmanship; (b) to cosmetic damage, including but not limited to
scratches, dents and broken plastic on ports; (c) to damage caused by
use with another product; (d) to damage caused by accident, abuse,
misuse, liquid contact, fire, earthquake or other external cause; (e)
to damage caused by operating the Apple Product outside Apple’s
published guidelines; (f) to damage caused by service (including
upgrades and expansions) performed by anyone who is not a
representative of Apple or an Apple Authorized Service Provider
(“AASP”); (g) to an Apple Product that has been modified to alter
functionality or capability without the written permission of Apple;
(h) to defects caused by normal wear and tear or otherwise due to the
normal aging of the Apple Product, or (i) if any serial number has
been removed or defaced from the Apple Product.

As you probably read, the quote above never mentions Apple branded accessories.


Apple Inc. of One Infinite Loop, Cupertino, California, U.S.A. 95014
(“Apple”) warrants the Apple-branded iPhone, iPad or iPod hardware
product and accessories contained in the original packaging (“Apple
Product”) against defects in materials and workmanship when used
normally in accordance with Apple's published guidelines for a period
of ONE (1) YEAR from the date of original retail purchase by the
end-user purchaser (&quot;Warranty Period&quot;). Apple’s published guidelines
include but are not limited to information contained in technical
specifications, user manuals and service communications.

Links
Legal Warranty