made test_decap to check both DSCP/TTL modes for SONiC 202012 and lat…

…er (#3887)

Description of PR
Summary: made test_decap to check both DSCP/TTL modes for SONiC 202012 and later
Fix #3355

uniform mode for ttl and dscp became available for IPinIP tunnel configuration starting from 202012 so made the test to run with ttl/dscp uniform mode for OS ver 202012 and later.

Approach
What is the motivation for this PR?
Adapt the test to covered feature improvements

How did you do it?
Parametrized the test to run with uniform ttl/dscp mode if supported for a given OS ver

How did you verify/test it?
py.test --inventory=../ansible/lab,../ansible/veos --testbed_file=../ansible/testbed.csv --module-path=../ansible/library -v -rA --topology=any decap/test_decap.py

tests/decap/conftest.py

@@ -27,3 +27,49 @@ def pytest_addoption(parser):
         default=True,
         help="Specify whether inner layer IPv6 testing will be covered",
     )
+
+    decap_group.addoption(
+        "--ttl_uniform",
+        action="store_true", 
+        default=False,
+        help="indicates TTL uniform is supported"
+    )
+    decap_group.addoption(
+        "--dscp_uniform",
+        action="store_true",
+        default=True,
+        help="indicates DSCP uniform is supported"
+    )
+    decap_group.addoption(
+        "--no_ttl_uniform",
+        dest='ttl_uniform',
+        action="store_false",
+        help="indicates TTL uniform is not supported"
+    )
+    decap_group.addoption(
+        "--no_dscp_uniform",
+        dest='dscp_uniform',
+        action="store_false",
+        help="indicates DSCP uniform is not supported"
+    )
+
+
+def build_ttl_dscp_params(uniform_support_info):
+    ttl_uni = {'ttl': 'uniform', 'dscp': 'pipe'}
+    dscp_uni = {'ttl': 'pipe', 'dscp': 'uniform'}
+    both_pipe = {'ttl': 'pipe', 'dscp': 'pipe'}
+    params = []
+    if uniform_support_info['ttl']:
+        params.append(ttl_uni)
+    if uniform_support_info['dscp']:
+        params.append(dscp_uni)
+    if len(params) < 2:
+        params.append(both_pipe)
+    return params
+
+def pytest_generate_tests(metafunc):
+  ttl = metafunc.config.getoption("ttl_uniform")
+  dscp = metafunc.config.getoption("dscp_uniform")
+  if "supported_ttl_dscp_params" in metafunc.fixturenames:
+      params = build_ttl_dscp_params({'ttl': ttl, 'dscp': dscp})
+      metafunc.parametrize("supported_ttl_dscp_params", params, ids=lambda p: "ttl=%s, dscp=%s" % (p['ttl'], p['dscp']))

tests/decap/test_decap.py

@@ -28,27 +28,29 @@
 ]
 
 
+@pytest.fixture(scope='module')
+def ttl_dscp_params(duthost, supported_ttl_dscp_params):
+    if "uniform" in supported_ttl_dscp_params.values() and ("201811" in duthost.os_version or "201911" in duthost.os_version):
+        pytest.skip('uniform ttl/dscp mode is available from 202012. Current version is %s' % duthost.os_version)
+
+    return supported_ttl_dscp_params
+
+
 @pytest.fixture(scope="module")
-def setup_teardown(request, duthosts, fib_info_files, duts_running_config_facts):
+def setup_teardown(request, duthosts, fib_info_files, duts_running_config_facts, ttl_dscp_params):
 
     is_multi_asic = duthosts[0].sonichost.is_multi_asic
 
-    # Initialize parameters
-    if "201811" in duthosts[0].os_version or "201911" in duthosts[0].os_version:
-        dscp_mode = "pipe"
-    else:
-        dscp_mode = "uniform"
-
     ecn_mode = "copy_from_outer"
-    ttl_mode = "pipe"
+    dscp_mode = ttl_dscp_params['dscp']
+    ttl_mode = ttl_dscp_params['ttl']
 
     # The hostvars dict has definitions defined in ansible/group_vars/sonic/variables
     hostvars = duthosts[0].host.options["variable_manager"]._hostvars[duthosts[0].hostname]
     sonic_hwsku = duthosts[0].sonichost.facts["hwsku"]
     mellanox_hwskus = hostvars.get("mellanox_hwskus", [])
 
     if sonic_hwsku in mellanox_hwskus:
-        dscp_mode = "uniform"
         ecn_mode = "standard"
 
     setup_info = {
@@ -133,7 +135,7 @@ def set_mux_random(tbinfo, mux_server_url):
     return set_mux_side(tbinfo, mux_server_url, 'random')
 
 
-def test_decap(tbinfo, duthosts, mux_server_url, setup_teardown, ptfhost, set_mux_random):
+def test_decap(tbinfo, duthosts, mux_server_url, setup_teardown, ptfhost, set_mux_random, ttl_dscp_params):
 
     setup_info = setup_teardown