Output filename extension can take precedence over format

[ubaltaci]

Hi, I don't know it is an expected behaviour or not, but I could not found similar issue or docs about it.

while Sharp("test_image.png").jpeg().toFile("test.jpeg") converts png to jpeg correctly,
if I change output file extension something different than jpeg, it keeps png formatSharp("test_image.png").jpeg().toFile("test.tmp")

sharp 0.12.2
vips 8.2.1
node v4.2.6
OS X 10.11

[lovell]

Hello, good spot on this. You're quite right that the output filename extension takes precedence over any output format, and if it can't be parsed will revert to the input format. Thanks for reporting!

[lovell]

Commit 677b2b9 adds a fix and test case for this scenario.

[lovell]

v0.13.0 now available with this fix, thanks for the original report.