Trailing whitespace not working

[revolter]

I just installed pre-commit, added this .pre-commit-config.yaml file:

# See http://pre-commit.com for more information
# See http://pre-commit.com/hooks.html for more hooks
repos:
-   repo: https://github.com/pre-commit/pre-commit-hooks
    sha: v1.1.1
    hooks:
    -   id: trailing-whitespace

and added a trailing space to a line in a file in the project, staged it, and when I commit it, it commits with the space, instead of removing it.

[asottile]

Can you produce the full output of your git commit as well as git show of that commit?

[chriskuehl]

Also, did you actually install the pre-commit hook to your git repo (e.g. run pre-commit install) after installing pre-commit?

[revolter]

@asottile

git commit -m "test":

[feature/git-hooks d80bc2bb4] test
 1 file changed, 2 insertions(+), 2 deletions(-)

git show:

commit d80bc2bb4f58a7c6ec93c345bd6f5252537c6d5a
Author: Iulian Onofrei <iulian.onofrei@yahoo.com>
Date:   Mon Nov 27 20:16:42 2017 +0200

    test

diff --git a/Libraries/IOUtilities/NSString+IOUtilities.m b/Libraries/IOUtilities/NSString+IOUtilities.m
index 07192cc25..1d9d469ea 100644
--- a/Libraries/IOUtilities/NSString+IOUtilities.m
+++ b/Libraries/IOUtilities/NSString+IOUtilities.m
@@ -394,8 +394,8 @@
 						}
 					}
 
-					if ([nextChar hasSuffix:@" --"]) {
+					if ([nextChar hasSuffix:@" --"]) { (before this is a space)
 					}
 
 					if ([nextCharMutable isEmpty]) {

The exact string (before this is a space) was added by me.

@chriskuehl, Yes, ls -al .git/hooks:

total 8
drwxr-xr-x   3 revolt  staff    96 Nov 26 16:24 .
drwxr-xr-x@ 18 revolt  staff   576 Nov 27 20:17 ..
-rwxr-xr-x   1 revolt  staff  1585 Nov 26 23:32 pre-commit

[asottile]

@revolter perplexing! It seems that pre-commit isn't even being run (I'd expect at the very least some output before the commit message)

Can you try this while a file is staged

bash -x .git/hooks/pre-commit

[asottile]

also can you produce:

env | grep -i '^git'

[revolter]

bash -x .git/hooks/pre-commit:

++ dirname .git/hooks/pre-commit
+ pushd .git/hooks
++ pwd
+ HERE=/Users/revolt/Development/ProjectName/.git/hooks
+ popd
+ retv=0
+ args=
+ ENV_PYTHON=/usr/local/Cellar/pre-commit/1.4.1/libexec/bin/python3.6
+ SKIP_ON_MISSING_CONF=false
+ which pre-commit
+ exe=pre-commit
+ run_args=
+ '[' -x /Users/revolt/Development/ProjectName/.git/hooks/pre-commit.legacy ']'
++ git rev-parse --show-toplevel
+ CONF_FILE=/Users/revolt/Development/ProjectName/.pre-commit-config.yaml
+ '[' '!' -f /Users/revolt/Development/ProjectName/.pre-commit-config.yaml ']'
+ pre-commit run --config .pre-commit-config.yaml
Trim Trailing Whitespace.................................................Failed
hookid: trailing-whitespace

Files were modified by this hook. Additional output:

Fixing Libraries/IOUtilities/NSString+IOUtilities.m

+ retv=1
+ exit 1

and it removed the trailing space of that file in the working tree.

env | grep -i '^git' outputs nothing.

[asottile]

ok so the script works as expected, now to figure out why git isn't committing as expected :S

Maybe it's something in gitconfig? cat ~/.gitconfig + cat .git/config (make sure to strip anything sensitive!)

Also might be useful:

GIT_TRACE=1 git commit -m "test"

[revolter]

Found the culprit, I previously (some months ago) changed the git hooksPath config trying to create my own hooks, so it was looking for hooks in another folder, thank you a lot for the help!

[revolter]

Also, the desired behaviour is for it to change the working tree, and after manually reviewing the changes that pre-commit did, stage them and commit again?

[asottile]

Yep, this approach was taken as hooks can sometimes be wrong and it allows the human some chance to double check the machine.

[revolter]

Maybe this could be added to a FAQ?

[asottile]

fwiw, I think we're going to handle core.hooksPath better, I've opened an issue for it: pre-commit/pre-commit#636

As for the modification faq bit I'd love to add something more to the documentation about this. The current docs briefly mention that modification is considered a failure, but don't really go in depth on the rationale: http://pre-commit.com/#new-hooks

If you'd like to contribute something in that direction, the docs are hosted via github pages: https://github.com/pre-commit/pre-commit.github.io

[asottile]

Also, big thanks for this issue, definitely something I hadn't even considered before 👏

[revolter]

Neither did I 😂 We go lucky I found it by mistake and fixed it easily, so others wouldn't suffer.