Add route flow counter related test cases

[Junchao-Mellanox]

Description of PR

Summary:
Added test cases for route flow counter feature. HLD: sonic-net/SONiC#908

Type of change

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

Back port request

• 201911

Approach

What is the motivation for this PR?

Add route flow counter related test cases

How did you do it?

1. Add new test case file test_route_flow_counter.py to covers basic function of this feature
2. Add check in test_vnet_vxlan.py to cover VNET route
3. Add check in test_bgp_speaker.py to cover BGP route
4. Add check in test_static_route.py to cover static route

How did you verify/test it?

Run the test cases

Any platform specific information?

N/A

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

N/A

Documentation

[Junchao-Mellanox]

Hi @keboliu and @roysr-nv , could you please sign-off as there is no change compare to previous approved one?

[lgtm-com]

This pull request introduces 2 alerts when merging 8e31615 into a923c95 - view on LGTM.com

new alerts:

• 2 for Unused import

[lgtm-com]

This pull request introduces 2 alerts when merging a9803fb into 6798d2b - view on LGTM.com

new alerts:

• 2 for Unused import

[Junchao-Mellanox]

/azpw run Azure.sonic-mgmt

[mssonicbld]

/AzurePipelines run Azure.sonic-mgmt

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[lgtm-com]

This pull request introduces 2 alerts when merging 589528d into 9932069 - view on LGTM.com

new alerts:

• 2 for Unused import

[lgtm-com]

This pull request introduces 3 alerts when merging 9daf6d1 into 0b86347 - view on LGTM.com

new alerts:

• 3 for Unused import

[Junchao-Mellanox]

Hi @liat-grozovik , could you please help merge this ?

[zhangyanzhao]

@Junchao-Mellanox can you please add this code PR into sonic-net/SONiC#908 for tracking? Thanks.

[Junchao-Mellanox]

@Junchao-Mellanox can you please add this code PR into sonic-net/SONiC#908 for tracking? Thanks.

Done

[ZhaohuiS]

@Junchao-Mellanox Does the script test_route_flow_counter support T1? Is the pytestmark same with test_static_router.py? Or it only supports mellanox?
Whatever same or not, could you please add pytestmark for this script? Otherwise it will skipped in our nightly test.
testcase route/test_route_flow_counter.py::TestRouteCounter::test_max_match_count is skipped when no topology marker is given

pytestmark = [
    pytest.mark.topology('t0'),
    pytest.mark.device_type('vs')
]