[Platform API] Add test cases for new API methods

[Junchao-Mellanox]

Description of PR

Summary:
During SONiC physical entity MIB feature development, a few new platform APIs were added and they need regression test cases to verify them.

Depends on sonic-net/sonic-platform-common#134

Type of change

• Bug fix
• Testbed and Framework(new/improvement)
• Test case(new/improvement)

Approach

What is the motivation for this PR?

Add test cases and test support for all newly added platform API introduced by SONiC physical entity MIB feature

How did you do it?

Add new API test support for chassis, fan, fan drawer, psu, sfp and add new test cases for them.

How did you verify/test it?

Manually run the regression

Any platform specific information?

N/A

Supported testbed topology if it's a new test case?

N/A

Documentation

[lgtm-com]

This pull request introduces 2 alerts and fixes 2 when merging 601477b into 7d140d5 - view on LGTM.com

new alerts:

• 2 for Except block handles 'BaseException'

fixed alerts:

• 2 for Unused import

[lgtm-com]

This pull request fixes 2 alerts when merging 8c84817 into 18a1540 - view on LGTM.com

fixed alerts:

• 2 for Unused import

[lgtm-com]

This pull request fixes 2 alerts when merging d4734bd into 18a1540 - view on LGTM.com

fixed alerts:

• 2 for Unused import

[lgtm-com]

This pull request fixes 2 alerts when merging 798f6c5 into 18a1540 - view on LGTM.com

fixed alerts:

• 2 for Unused import

[lgtm-com]

This pull request fixes 2 alerts when merging b02b4d3 into 4b3fa1c - view on LGTM.com

fixed alerts:

• 2 for Unused import

[jleveque]

@Junchao-Mellanox: Since these methods are inherited from DeviceBase, there are other classes which inherit these methods. Even though they may not be used by the MIB, we should test that the APIs are implemented for completeness. Do you agree? If so, can you please add similar API tests to the following files and their respective helpers?

• test_component.py
• test_fan_drawer_fans.py
• test_module.py
• test_psu_fans.py

[Junchao-Mellanox]

@Junchao-Mellanox: Since these methods are inherited from DeviceBase, there are other classes which inherit these methods. Even though they may not be used by the MIB, we should test that the APIs are implemented for completeness. Do you agree? If so, can you please add similar API tests to the following files and their respective helpers?

• test_component.py
• test_fan_drawer_fans.py
• test_module.py
• test_psu_fans.py

Agree, will do it.