[everflow]: Make Policer test more robust

[nazariig]

Signed-off-by: Nazarii Hnydyn [email protected]

Description of PR

Fixed everflow Policer test: logic was made more robust

Type of change

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

Approach

How did you do it?

• Changed packet generator logic: send all packets at full rate
• Added CBS bucket refill calculation
• Default tolerance is 10%

How did you verify/test it?

1. Deploy t1-lag
2. Run test

root@93d22705bd72:~# ./run.sh
everflow_policer_test.EverflowPolicerTest ...
Recieved 500 original packets
Received 100 mirrored packets after rate limiting
ok

----------------------------------------------------------------------
Ran 1 test in 3.423s

OK

3. The test will print nice user friendly assert in case of failure

root@93d22705bd72:~# ./run.sh
everflow_policer_test.EverflowPolicerTest ...
Recieved 500 original packets
Received 88 mirrored packets after rate limiting
FAIL

======================================================================
FAIL: everflow_policer_test.EverflowPolicerTest
----------------------------------------------------------------------
Traceback (most recent call last):
  File "acstests/everflow_policer_test.py", line 212, in runTest
    assert count >= self.min_range and count <= self.max_range, assert_str
AssertionError: min(90) <= count(88) <= max(110)

----------------------------------------------------------------------
Ran 1 test in 2.911s

FAILED (failures=1)
No handlers could be found for logger "dataplane"

******************************************
ATTENTION: SOME TESTS DID NOT PASS!!!

The following tests failed:
EverflowPolicerTest

******************************************

Any platform specific information?

• N/A

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

• N/A

Documentation

• N/A

[qiluo-msft]

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