Fix test_m2o_fluctuating_lossless

tests/common/snappi_tests/common_helpers.py

@@ -1486,6 +1486,85 @@ def get_pfcQueueGroupSize(default=8):
     return default
 
 
+def get_queue_scheduler_weight_dict(host_ans, asic_value=None, port=None,
+                                    qos_map_profile=None):
+    """
+    Build a per-queue scheduler/weight map for an interface by joining the
+    ``QUEUE`` and ``SCHEDULER`` config-DB tables, and optionally annotating
+    each queue with one of its DSCP values via ``DSCP_TO_TC_MAP`` and
+    ``TC_TO_QUEUE_MAP``.
+
+    Args:
+        host_ans: Ansible host instance of the device.
+        asic_value: asic namespace; pass ``None`` (default) or the string
+            ``"None"`` for single-asic devices.
+        port (str, optional): interface name to read ``QUEUE`` for. Defaults
+            to the first interface present in ``QUEUE``.
+        qos_map_profile (str, optional): name of the profile inside
+            ``DSCP_TO_TC_MAP`` / ``TC_TO_QUEUE_MAP`` to use for the ``dscp``
+            field. Defaults to the first profile (typically ``"AZURE"``).
+            If the maps are missing, ``dscp`` is set to ``None``.
+
+    Returns:
+        dict[int, dict]: ``{queue: {"scheduler": <name>, "type": <DWRR/...>,
+        "weight": <int>, "dscp": <int|None>}}``. The result always covers
+        queues 0-7; any queue not present in the per-port ``QUEUE`` config
+        (or whose scheduler is missing from ``SCHEDULER``) falls back to a
+        default entry with equal DWRR weight 15.
+    """
+    if asic_value in (None, "None"):
+        config_facts = host_ans.config_facts(host=host_ans.hostname,
+                                             source="running")["ansible_facts"]
+    else:
+        config_facts = host_ans.config_facts(host=host_ans.hostname,
+                                             source="running",
+                                             namespace=asic_value)["ansible_facts"]
+
+    queue_cfg_all = config_facts.get("QUEUE") or {}
+    scheduler_cfg = config_facts.get("SCHEDULER") or {}
+
+    dscp_to_tc = config_facts.get("DSCP_TO_TC_MAP") or {}
+    tc_to_queue = config_facts.get("TC_TO_QUEUE_MAP") or {}
+    if qos_map_profile is None and dscp_to_tc:
+        qos_map_profile = next(iter(dscp_to_tc))
+    dscp_to_tc_map = dscp_to_tc.get(qos_map_profile, {}) if qos_map_profile else {}
+    tc_to_queue_map = tc_to_queue.get(qos_map_profile, {}) if qos_map_profile else {}
+
+    queue_to_dscp = {}
+    for dscp, tc in dscp_to_tc_map.items():
+        q = tc_to_queue_map.get(str(tc))
+        if q is not None:
+            queue_to_dscp.setdefault(int(q), int(dscp))
+
+    # default entry with equal DWRR weight 15
+    result = {
+        q: {"scheduler": None, "type": "DWRR", "weight": 15,
+            "dscp": queue_to_dscp.get(q)}
+        for q in range(8)
+    }
+
+    if not queue_cfg_all:
+        return result
+
+    if port is None:
+        port = next(iter(queue_cfg_all))
+    if port not in queue_cfg_all:
+        raise KeyError("Port {} not found in QUEUE config (available: {})".format(port, sorted(queue_cfg_all)))
+
+    for q, value in queue_cfg_all[port].items():
+        scheduler = value.get("scheduler")
+        if scheduler is None or scheduler not in scheduler_cfg:
+            continue
+        sched = scheduler_cfg[scheduler]
+        result[int(q)] = {
+            "scheduler": scheduler,
+            "type": sched.get("type"),
+            "weight": int(sched["weight"]),
+            "dscp": queue_to_dscp.get(int(q)),
+        }
+    return result
+
+
 @lru_cache
 def get_testbed_from_args():
     parser = ArgumentParser()

tests/common/unit_tests/snappi_tests/README.md

@@ -0,0 +1,48 @@
+# Unit Tests for `tests/common/snappi_tests/`
+
+This directory contains unit tests for modules under
+`tests/common/snappi_tests/`.
+
+## Running Unit Tests
+
+### Run all unit tests in this directory
+```bash
+# From repository root
+python3 -m pytest --noconftest tests/common/unit_tests/snappi_tests/ -v
+```
+
+### Run a specific test file
+```bash
+python3 -m pytest --noconftest \
+  tests/common/unit_tests/snappi_tests/unit_test_common_helpers.py -v
+```
+
+### Run a specific test case
+```bash
+python3 -m pytest --noconftest \
+  tests/common/unit_tests/snappi_tests/unit_test_common_helpers.py::test_get_queue_scheduler_weight_dict \
+  -v
+```
+
+## Why `--noconftest`
+
+`tests/conftest.py` pulls in integration-test dependencies (for example,
+`paramiko`) that are not needed for these isolated unit tests. Using
+`--noconftest` keeps the run lightweight and avoids unrelated import
+failures.
+
+The target module `tests/common/snappi_tests/common_helpers.py` itself
+imports heavy dependencies (`tests.conftest`, `ipaddr`, mellanox helpers,
+etc.) at import time. To stay dependency-free, the unit tests load only the
+function under test by parsing the source with `ast` and `exec`-ing the
+single function definition in an isolated namespace. No real DUT, Ansible
+inventory, or Snappi environment is required.
+
+If your environment has the full sonic-mgmt test dependencies installed and
+you intentionally want global fixtures, you can remove `--noconftest`.
+
+## Requirements
+
+- Python 3
+- `pytest`
+- `unittest.mock` (built into Python standard library)

tests/common/unit_tests/snappi_tests/unit_test_common_helpers.py

@@ -0,0 +1,111 @@
+"""Unit test for ``get_queue_scheduler_weight_dict`` in
+``tests/common/snappi_tests/common_helpers.py``.
+
+The target module imports heavy sonic-mgmt deps at import time, so we
+extract the function under test via ``ast`` and exec it in an isolated
+namespace.
+
+Run with::
+
+    python3 -m pytest --noconftest \\
+        tests/common/unit_tests/snappi_tests/unit_test_common_helpers.py -v
+"""
+
+import ast
+from pathlib import Path
+from unittest.mock import MagicMock
+
+
+MODULE_PATH = (Path(__file__).resolve().parents[3] /
+               "common/snappi_tests/common_helpers.py")
+
+
+def _load(name):
+    tree = ast.parse(MODULE_PATH.read_text())
+    for node in tree.body:
+        if isinstance(node, ast.FunctionDef) and node.name == name:
+            ns = {}
+            exec(compile(ast.Module(body=[node], type_ignores=[]),
+                         str(MODULE_PATH), "exec"), ns)
+            return ns[name]
+    raise LookupError(name)
+
+
+# Minimal config_facts modeling the str-msn2700-22 (Mellanox-SN2700) DUT,
+# trimmed to the keys read by ``get_queue_scheduler_weight_dict``:
+#   scheduler.0 -> lossy queues, DWRR weight 14
+#   scheduler.1 -> lossless queues 3 & 4, DWRR weight 15
+CONFIG_FACTS = {
+    "QUEUE": {
+        "Ethernet100": {
+            "0": {"scheduler": "scheduler.0"},
+            "1": {"scheduler": "scheduler.0"},
+            "2": {"scheduler": "scheduler.0"},
+            "3": {"scheduler": "scheduler.1",
+                  "wred_profile": "AZURE_LOSSLESS"},
+            "4": {"scheduler": "scheduler.1",
+                  "wred_profile": "AZURE_LOSSLESS"},
+            "5": {"scheduler": "scheduler.0"},
+            "6": {"scheduler": "scheduler.0"},
+        },
+    },
+    "SCHEDULER": {
+        "scheduler.0": {"type": "DWRR", "weight": "14"},
+        "scheduler.1": {"type": "DWRR", "weight": "15"},
+    },
+    "DSCP_TO_TC_MAP": {
+        "AZURE": {
+            "0": "1", "1": "1", "10": "1", "11": "1", "12": "1", "13": "1",
+            "14": "1", "15": "1", "16": "1", "17": "1", "18": "1", "19": "1",
+            "2": "1", "20": "1", "21": "1", "22": "1", "23": "1", "24": "1",
+            "25": "1", "26": "1", "27": "1", "28": "1", "29": "1", "3": "3",
+            "30": "1", "31": "1", "32": "1", "33": "1", "34": "1", "35": "1",
+            "36": "1", "37": "1", "38": "1", "39": "1", "4": "4", "40": "1",
+            "41": "1", "42": "1", "43": "1", "44": "1", "45": "1", "46": "5",
+            "47": "1", "48": "6", "49": "1", "5": "2", "50": "1", "51": "1",
+            "52": "1", "53": "1", "54": "1", "55": "1", "56": "1", "57": "1",
+            "58": "1", "59": "1", "6": "1", "60": "1", "61": "1", "62": "1",
+            "63": "1", "7": "1", "8": "0", "9": "1",
+        },
+    },
+    "TC_TO_QUEUE_MAP": {
+        "AZURE": {str(i): str(i) for i in range(8)},
+    },
+}
+
+EXPECTED = {
+    0: {"scheduler": "scheduler.0", "type": "DWRR", "weight": 14, "dscp": 8},
+    1: {"scheduler": "scheduler.0", "type": "DWRR", "weight": 14, "dscp": 0},
+    2: {"scheduler": "scheduler.0", "type": "DWRR", "weight": 14, "dscp": 5},
+    3: {"scheduler": "scheduler.1", "type": "DWRR", "weight": 15, "dscp": 3},
+    4: {"scheduler": "scheduler.1", "type": "DWRR", "weight": 15, "dscp": 4},
+    5: {"scheduler": "scheduler.0", "type": "DWRR", "weight": 14, "dscp": 46},
+    6: {"scheduler": "scheduler.0", "type": "DWRR", "weight": 14, "dscp": 48},
+    # Queue 7 is not in the per-port QUEUE config; falls back to default.
+    7: {"scheduler": None, "type": "DWRR", "weight": 15, "dscp": None},
+}
+
+
+def test_get_queue_scheduler_weight_dict():
+    host = MagicMock()
+    host.hostname = "test_dut"
+    host.config_facts.return_value = {"ansible_facts": CONFIG_FACTS}
+
+    assert _load("get_queue_scheduler_weight_dict")(host) == EXPECTED
+
+
+def test_get_queue_scheduler_weight_dict_defaults_when_unconfigured():
+    """When QUEUE/SCHEDULER are absent, fall back to 8 queues w/ equal weights."""
+    host = MagicMock()
+    host.hostname = "test_dut"
+    facts = {k: v for k, v in CONFIG_FACTS.items()
+             if k not in ("QUEUE", "SCHEDULER")}
+    host.config_facts.return_value = {"ansible_facts": facts}
+
+    result = _load("get_queue_scheduler_weight_dict")(host)
+    assert set(result) == set(range(8))
+    assert {v["weight"] for v in result.values()} == {15}
+    assert {v["type"] for v in result.values()} == {"DWRR"}
+    # DSCP annotations from DSCP_TO_TC_MAP / TC_TO_QUEUE_MAP still apply.
+    assert result[0]["dscp"] == 8
+    assert result[3]["dscp"] == 3