fix: Pre-commit-terraform terraform_validate hook

[nshenry03]

Put an x into the box if that apply:

• This PR introduces breaking change.
• This PR fixes a bug.
• This PR adds new functionality.
• This PR enhances existing functionality.

Description of your changes

This PR simple redirects stdout and stderror to /dev/null for the cd command.

Fixes hooks/terraform_validate.sh

The terraform_validate hook was failing for me because the script was getting No such file or directory error:

hnicholas@hnicholas-a01:~/Repositories/terraform/modules/aws/kms$ pre-commit run -a
Terraform fmt............................................................Passed
Terraform validate.......................................................Failed
- hook id: terraform_validate
- exit code: 1

/Users/hnicholas/.cache/pre-commit/repo7ebw704n/hooks/terraform_validate.sh: line 114: pushd: $'/Users/hnicholas/Repositories/terraform/modules/aws/kms/examples/backend_account\n/Users/hnicholas/Repositories/terraform/modules/aws/kms/examples/backend_account': No such file or directory

Terraform docs...........................................................Passed
Terraform validate with tflint...........................................Passed
Terraform validate with tfsec............................................Passed
check for added large files..............................................Passed
check for merge conflicts................................................Passed
don't commit to branch...................................................Passed

Digging deeper, it seems that cd was outputting the name of the directory, but we don't want that, we only want output from pwd -P.

How can we test changes

I changed this locally and it fixed the issue.

[yermulnik]

@nshenry03 cd by default shouldn't output dirname it changed directory to.
Can you please share the output of type cd command?

[nshenry03]

Thanks @yermulnik, here is the output from type cd:

$ type cd
cd is a shell builtin

It seems to for me

$ cd Repositories/terraform/modules/aws/kms/
/Users/hnicholas/Repositories/terraform/modules/aws/kms
$

System Info

$ system_profiler SPSoftwareDataType
Software:

    System Software Overview:

      System Version: macOS 11.6.7 (20G630)
      Kernel Version: Darwin 20.6.0
      Boot Volume: Macintosh HD
      Boot Mode: Normal
      Computer Name: hnicholas-a01
      User Name: Nicholas Henry (hnicholas)
      Secure Virtual Memory: Enabled
      System Integrity Protection: Enabled
      Time since boot: 10 days 21:01

$ echo $SHELL
/usr/local/bin/bash

$ ll /usr/local/bin/bash
lrwxr-xr-x  1 hnicholas  admin  30 Jan 14 09:16 /usr/local/bin/bash@ -> ../Cellar/bash/5.1.16/bin/bash

$ brew info bash
bash: stable 5.1.16 (bottled), HEAD
Bourne-Again SHell, a UNIX command interpreter
https://www.gnu.org/software/bash/
/usr/local/Cellar/bash/5.1.16 (157 files, 10.9MB) *
  Poured from bottle on 2022-01-14 at 09:16:49
From: https://github.com/Homebrew/homebrew-core/blob/HEAD/Formula/bash.rb
License: GPL-3.0-or-later
==> Options
--HEAD
        Install HEAD version
==> Analytics
install: 21,000 (30 days), 64,439 (90 days), 311,670 (365 days)
install-on-request: 16,991 (30 days), 52,064 (90 days), 256,604 (365 days)
build-error: 33 (30 days)

[yermulnik]

On the other hand shell scripts shouldn't be taking into account aliases and functions 🤔 What's your OS and Bash versions?

[yermulnik]

Aha, that's because of CDPATH var:

 If a non-empty directory name from CDPATH is used, or if - is the first argument, and the directory change is successful, the absolute pathname of the new working directory is written to the standard output.

So we only need to suppress stdout. I'll leave a commit suggestion in a sec.

[yermulnik]

LGTM

[yermulnik]

Once @MaxymVlasov and/or @antonbabenko make it to this PR to do the review, it will be merged.

@nshenry03 Thanks for contribution.

[antonbabenko]

This PR is included in version 1.72.2 🎉

[MaxymVlasov]

Heh, you found code written in Paleolithic.

Let's try reuse logic that used in common functions here:

https://github.com/antonbabenko/pre-commit-terraform/blob/master/hooks/_common.sh#L178

Absolutely have no idea why it was written in so complex way