The --syntax-check option can not test dynamically included files.

[letompouce]

$ figlet 'py.test' >> roles/mongodb/task/mongodb_armv7l.yml
$ py.test
======================================================================================================= test session starts =======================================================================================================
platform linux2 -- Python 2.7.9, pytest-3.0.3, py-1.4.31, pluggy-0.4.0
rootdir: /home/tom/dev/ansiblecube, inifile: 
collected 61 items 

tests/test_ansible.py ....................
tests/test_syntax.py .........................................

==================================================================================================== 61 passed in 5.24 seconds ====================================================================================================

[letompouce]

A file has an include statement, which depends on some variable:

$ head -n 3 roles/mongodb/tasks/main.yml
---
- include: mongodb_{{ ansible_architecture }}.yml

This file is not included when running ansible-playbook --syntax-check:

$ ansible-playbook main.yml --syntax-check
statically included: /home/tom/dev/ansiblecube/roles/system/tasks/ralink.yml
statically included: /home/tom/dev/ansiblecube/roles/system/tasks/realtek.yml
statically included: /home/tom/dev/ansiblecube/roles/system/tasks/lime2.yml
statically included: /home/tom/dev/ansiblecube/roles/ideascube/tasks/branding.yml
statically included: /home/tom/dev/ansiblecube/roles/ideascube/tasks/ideascube.yml
statically included: /home/tom/dev/ansiblecube/roles/ideascube/tasks/ext_hdd.yml
statically included: /home/tom/dev/ansiblecube/roles/ideascube/tasks/../../../post_install.yml
statically included: /home/tom/dev/ansiblecube/roles/kiwix/tasks/kiwix.yml
statically included: /home/tom/dev/ansiblecube/roles/kiwix/tasks/dust-removal.yml
statically included: /home/tom/dev/ansiblecube/roles/kiwix/tasks/update_catalog.yml
statically included: /home/tom/dev/ansiblecube/roles/kiwix/tasks/../../../post_install.yml
statically included: /home/tom/dev/ansiblecube/roles/mongodb/tasks/../../../post_install.yml
statically included: /home/tom/dev/ansiblecube/roles/mook/tasks/back_end.yml
statically included: /home/tom/dev/ansiblecube/roles/mook/tasks/front_end.yml
statically included: /home/tom/dev/ansiblecube/roles/mook/tasks/system.yml
statically included: /home/tom/dev/ansiblecube/roles/mook/tasks/../../../post_install.yml
statically included: /home/tom/dev/ansiblecube/roles/mook/tasks/back_end.yml
statically included: /home/tom/dev/ansiblecube/roles/mook/tasks/front_end.yml
statically included: /home/tom/dev/ansiblecube/roles/mook/tasks/system.yml
statically included: /home/tom/dev/ansiblecube/roles/mook/tasks/../../../post_install.yml
statically included: /home/tom/dev/ansiblecube/roles/appinventor/tasks/appinventor.yml
statically included: /home/tom/dev/ansiblecube/roles/appinventor/tasks/../../../post_install.yml
statically included: /home/tom/dev/ansiblecube/roles/kalite/tasks/kalite.yml
statically included: /home/tom/dev/ansiblecube/roles/kalite/tasks/ext_hdd.yml
statically included: /home/tom/dev/ansiblecube/roles/kalite/tasks/import_videos.yml
statically included: /home/tom/dev/ansiblecube/roles/kalite/tasks/../../../post_install.yml

playbook: main.yml

So many tasks files are not tested.

[letompouce]

One of the lead devs makes it clear,

It cannot check syntax of dynamically included files, this would also affect include and include_roles. Since those would need actually executing the tasks.