Support the CLI option by which dynamic buffer model can be enabled

Signed-off-by: Stephen Sun <stephens@nvidia.com>

tests/conftest.py

@@ -22,6 +22,8 @@
 from dvslib import dvs_mirror
 from dvslib import dvs_policer
 
+from buffer_model import enable_dynamic_buffer
+
 # FIXME: For the sake of stabilizing the PR pipeline we currently assume there are 32 front-panel
 # ports in the system (much like the rest of the test suite). This should be adjusted to accomodate
 # a dynamic number of ports. GitHub Issue: Azure/sonic-swss#1384.
@@ -71,6 +73,11 @@ def pytest_addoption(parser):
                      default=None,
                      help="Topology file for the Virtual Chassis Topology")
 
+    parser.addoption("--buffer_model",
+                     action="store",
+                     default="traditional",
+                     help="Buffer model")
+
 
 def random_string(size=4, chars=string.ascii_uppercase + string.digits):
     return "".join(random.choice(chars) for x in range(size))
@@ -221,7 +228,8 @@ def __init__(
         forcedvs: bool = None,
         vct: str = None,
         newctnname: str = None,
-        ctnmounts: Dict[str, str] = None
+        ctnmounts: Dict[str, str] = None,
+        buffer_model: str = None,
     ):
         self.basicd = ["redis-server", "rsyslogd"]
         self.swssd = [
@@ -366,6 +374,10 @@ def __init__(
         # Make sure everything is up and running before turning over control to the caller
         self.check_ready_status_and_init_db()
 
+        # Switch buffer model to dynamic if necessary
+        if buffer_model == 'dynamic':
+            enable_dynamic_buffer(self.get_config_db(), self.runcmd)
+
     def destroy(self) -> None:
         if self.appldb:
             del self.appldb
@@ -1477,10 +1489,11 @@ def dvs(request) -> DockerVirtualSwitch:
     keeptb = request.config.getoption("--keeptb")
     imgname = request.config.getoption("--imgname")
     max_cpu = request.config.getoption("--max_cpu")
+    buffer_model = request.config.getoption("--buffer_model")
     fakeplatform = getattr(request.module, "DVS_FAKE_PLATFORM", None)
     log_path = name if name else request.module.__name__
 
-    dvs = DockerVirtualSwitch(name, imgname, keeptb, fakeplatform, log_path, max_cpu, forcedvs)
+    dvs = DockerVirtualSwitch(name, imgname, keeptb, fakeplatform, log_path, max_cpu, forcedvs, buffer_model = buffer_model)
 
     yield dvs