Rule 602 (Don’t compare to empty string) find an error in shell script

[kazh000]

Summary

Linter finds an error of the rule 602 in shell code

Issue Type

• Bug Report

Ansible and Ansible Lint details

ansible 2.10.4
config file = None
configured module search path = ['/root/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
ansible python module location = /usr/local/lib/python3.6/site-packages/ansible
executable location = /usr/local/bin/ansible
python version = 3.6.12 (default, Dec 18 2020, 06:04:50) [GCC 8.3.0]

ansible-lint 5.0.0a1.dev8

• ansible installation method: pip
• ansible-lint installation method: pip

OS / ENVIRONMENT

Run in docker. Dockerfile:

FROM python:3.6

WORKDIR /usr/src/app

RUN pip install git+https://github.com/ansible-community/ansible-lint "ansible"

RUN ansible  --version

RUN ansible-lint --version

RUN echo "---\n- hosts: localhost\n  gather_facts: no\n  tasks:\n\
  - name: Reproduce the bug in the rule 602\n    shell: |\n\
      var=\$(pwd)\n      if [[ \"\$var\" == \"\" ]]; then echo test; fi\n    changed_when

RUN cat test.yml

RUN ansible-lint --force-color --show-relpath test.yml

STEPS TO REPRODUCE

docker build --rm -f Dockerfile .

Desired Behaviour

No error message

Actual Behaviour

Please give some details of what is actually happening.
Include a minimum complete verifiable example with:

• playbook
• output of running ansible-lint
• if you're getting a stack trace, output of
  ansible-playbook --syntax-check playbook

Step 1/9 : FROM python:3.6
 ---> bd4a91d81d7e
Step 2/9 : WORKDIR /usr/src/app
 ---> Using cache
 ---> 6b223c53a8f1
Step 3/9 : RUN pip install git+https://github.com/ansible-community/ansible-lint "ansible"
 ---> Using cache
 ---> 6af3b1194721
Step 4/9 : RUN ansible  --version
 ---> Running in c2b07e26d819
ansible 2.10.4
  config file = None
  configured module search path = ['/root/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/local/lib/python3.6/site-packages/ansible
  executable location = /usr/local/bin/ansible
  python version = 3.6.12 (default, Dec 18 2020, 06:04:50) [GCC 8.3.0]
Removing intermediate container c2b07e26d819
 ---> e319230a42c3
Step 5/9 : RUN ansible-lint --version
 ---> Running in 6130591acb07
ansible-lint 5.0.0a1.dev8
Removing intermediate container 6130591acb07
 ---> 5b4fde26df0d
Step 6/9 : RUN echo "---\n- hosts: localhost\n  gather_facts: no\n  tasks:\n  - name: Reproduce the bug in the rule 602\n    shell: |\n      var=\$(pwd)\n      if [[ \"\$var\" == \"\" ]]; then echo test; fi\n    changed_when: False" > test.yml
 ---> Running in 3d5ba620c413
Removing intermediate container 3d5ba620c413
 ---> 59509ff20919
Step 7/9 : RUN cat test.yml
 ---> Running in 736962797dc1
---
- hosts: localhost
  gather_facts: no
  tasks:
  - name: Reproduce the bug in the rule 602
    shell: |
      var=$(pwd)
      if [[ "$var" == "" ]]; then echo test; fi
    changed_when: False
Removing intermediate container 736962797dc1
 ---> af9ed683e9e1
Step 8/9 : RUN ansible-lint --force-color --show-relpath test.yml
 ---> Running in 62d37ee100d5
WARNING  Listing 1 violation(s) that are fatal
602: Don't compare to empty string
test.yml:8       if [[ "$var" == "" ]]; then echo test; fi
You can skip specific rules or tags by adding them to your configuration file:
# .ansible-lint
warn_list:  # or 'skip_list' to silence them completely
  - '602'  # Don't compare to empty string
Finished with 1 failure(s), 0 warning(s) on 1 files.
The command '/bin/sh -c ansible-lint --force-color --show-relpath test.yml' returned a non-zero code: 2