Format on save with black isn't working

When saving a file, [coc.nvim] Formatted with black is printed, but the file isn’t changed. Running call CocAction('format') also prints the message, but the file is then updated. The output from :CocCommand workspace.showOutput is as follows:

########## active formattor: black
execPath:   black
moduleName: black
args:       --diff,--quiet,/home/devneal/github/manim/manim/mobject/mobject.py.2c210016803c1db7200eb6ec681835ba.py

########## black output:
--- /home/devneal/github/manim/manim/mobject/mobject.py.2c210016803c1db7200eb6ec681835ba.py	2020-12-30 05:10:36.386043 +0000
+++ /home/devneal/github/manim/manim/mobject/mobject.py.2c210016803c1db7200eb6ec681835ba.py	2020-12-30 05:10:37.032054 +0000
@@ -1317,8 +1317,10 @@
 
         self.method = getattr(self.mobject.generate_target(), method_name)
 
         def build(*method_args, **method_kwargs):
             self.method(*method_args, **method_kwargs)
-            return _MethodAnimation(self.mobject, self.method, method_args,                method_kwargs)
+            return _MethodAnimation(
+                self.mobject, self.method, method_args, method_kwargs
+            )
 
         return build

It seems like a temp file may be being formatted instead of the actual file, but I don’t know if this is expected.

[fannheyward]

The latest coc has added coc.preferences.willSaveHandlerTimeout, you can increase this time limitation.

[swizzard]

aug python
  au!
  au BufWrite *.py call CocAction('format')
aug END

in my .nvimrc file worked for me