Update pcieutil error message on loading common pcie module

[cytsao1]

Currently, pcieutil will print the following message to console every time it is called if loading the common module:
root@sonic:/home/cisco# pcieutil show
Failed to load platform Pcie module. Error : No module named 'sonic_platform.pcie', fallback to load Pcie common utility.
==============================Display PCIe Device===============================

What I did

Update the error message to only be logged in syslog, rather than print to console.

How to verify it

Run any pcieutil command

Previous command output (if the output of a command-line utility has changed)

root@sonic:/home/cisco# pcieutil show
Failed to load platform Pcie module. Error : No module named 'sonic_platform.pcie', fallback to load Pcie common utility.
==============================Display PCIe Device===============================
......

New command output (if the output of a command-line utility has changed)

root@sonic:/home/cisco# pcieutil show
==============================Display PCIe Device===============================
.....

[cytsao1]

@abdosi Can this be reviewed?

[prgeor]

@cytsao1 please add code coverage for your changes

[cytsao1]

please add code coverage for your changes

@prgeor Do you mean to update this test file? https://github.com/sonic-net/sonic-utilities/blob/master/tests/pcieutil_test.py
or something else? This code should be invoked by any pcieutil command.

[prgeor]

please add code coverage for your changes

@prgeor Do you mean to update this test file? https://github.com/sonic-net/sonic-utilities/blob/master/tests/pcieutil_test.py or something else? This code should be invoked by any pcieutil command.

@cytsao1 yes

[cytsao1]

@prgeor Can this be reviewed now? Added test.

[prgeor]

@cytsao1 what does this ASSERT confirm? There could be platform which may not see this import Error and in which case this ASSERT may fail?

[cytsao1]

This test is to confirm that the import warning message will not be in the console output, whether the Import error is raised or not.

[prgeor]

@cytsao1 result value is empty string at the start, so when the test run at line 209, result is not updated at all and at line 213 ofcourse pcieutil_load_module_warning_msg won't match result value, so i don't understand why even run pcieutil.load_platform_pcieutils() at line 209?

[cytsao1]

sys.stdout is updated to be same IO stream as result, so running load_platform_pcieutil output will be captured in result instead of output to console stdout.
After, the stdout is set back to the sys.stdout stream.

[cytsao1]

Example of how it would look without this PR

>>> import sys
>>> from io import StringIO
>>> import pcieutil.main as pcieutil
>>> stdout = sys.stdout
>>> sys.stdout = result = StringIO()
>>> pcieutil.load_platform_pcieutil()
>>> sys.stdout = stdout
>>> result.getvalue()
"Failed to load platform Pcie module. Error : No module named 'sonic_platform.pcie', fallback to load Pcie common utility.\n"

[prgeor]

@cytsao1 thanks for clarifying....did not realize that stdout was captured in a string output...

[cytsao1]

Can someone with permissions merge this?

[bmridul]

@abdosi @prgeor
Pls help merge this.

[abdosi]

@prgeor can we merge this ?

[abdosi]

@prgeor can we merge this ?

@prgeor you comment is addressed above. Do we need more clarification ?