Unable to format ignored decorator in class

[USSRLivesOn]

Operating system: MacOS 10.14.3
Python version: 3.6.6
Black version: 18.9b0
Does also happen on master: Yes

Input:

class MyClass:

    # fmt: off
    @mydecorator
    # fmt: on
    def test_decorated(self):
        pass

foo = 'foo'

Result:
INTERNAL ERROR: Black produced code that is not equivalent to the source. Please report a bug on https://github.com/ambv/black/issues. This diff might be helpful: /var/folders/d6/wn1mqq2j05n50jjvrtk94scr0000gn/T/blk_xq234z_q.log

This is the minimal reproducing case I could reduce it to. Not exactly sure where the issue is, but I figured it would be helpful to file. Thanks for working on Black!

[zsol]

Looks like the indentation is messed up after # fmt: on in this case.

input:

class X:
  # fmt: off
  @lol
  # fmt: on
  def f():
    pass
f = 'f'

output:

class X:
    # fmt: off
  @lol
  # fmt: on
  def f():
    pass
    f = "f"

[pawelad]

Just encountered the same problem when trying to tell black not to format Click decorators but do format the rest of the file:

# fmt: off
@click.command()
@click.option(
    "--interactive", "-i",
    is_flag=True, default=False, show_default=True,
    help="Open the browser.",
)
# fmt: on
def foo(interactive):
	# Some ugly code here

[pawelad]

Actually, mine seems to be a duplicate of #560 - not sure if they're the same / related. Sorry for posting in the wrong thread if they're not.

[zsol]

Yep.
Duplicate of #560