Apple says a bug messed up Consumer Reports' MacBook Pro battery tests

Consumer Reports sparked controversy late last month when it put out a report saying it couldn't recommend Apple's new MacBook Pros on account of inconsistent battery life.

Naturally, Apple sprang into defense mode with Phil Schiller, the company's senior vice president of worldwide marketing, taking issue with the non-profit organization's testing methods. Schiller said Apple would work with Consumer Reports to understand their battery tests.

Well, it looks like Apple's figured out why Consumer Reports' MacBook Pro battery tests didn't match its own.

"We learned that when testing battery life on Mac notebooks, Consumer Reports uses a hidden Safari setting for developing websites which turns off the browser cache....," Apple said in a statement to Consumer Reports. "We have also fixed the bug uncovered in this test."

According to Consumer Reports, turning off the web browser's cache (a feature that stores website snippets on a computer's hard drive for quicker loading times later) is a standard part of its all of its laptop battery tests.

"We appreciate the opportunity to work with Consumer Reports over the holidays to understand their battery test results," Apple told Mashable. "This is not a setting used by customers and does not reflect real-world usage. [Consumer Reports’] use of this developer setting also triggered an obscure and intermittent bug reloading icons which created inconsistent results in their lab. After we asked Consumer Reports to run the same test using normal user settings, they told us their MacBook Pro systems consistently delivered the expected battery life.... This is the best pro notebook we’ve ever made, we respect Consumer Reports and we’re glad they decided to revisit their findings on the MacBook Pro."

Though the bug has been patched in the latest Beta Software Program release, Consumer Reports has not concluded new battery tests yet.

The non-profit says it'll run its tests again with the bug fix (and presumably with Safari's cache still turned off) and if the new battery results are "consistently high" it'll change its rating for the new MacBook Pros to "recommended."

"Consumer Reports is rerunning its battery life tests on the MacBook Pros with Safari's cache setting switched off, as per our normal protocol," a Consumer Reports rep told Mashable over email. "After downloading Apple's fix, we no longer expect this to cause wildly inconsistent battery life. If that's the case, the MacBook Pros will receive our recommendation. We'll have final results by the end of the week."

UPDATE: Jan. 10, 2017, 2:34 p.m. EST Added update from Consumer Reports on its testing methodology post-software update.