test: add scenario CLI smoke and NS-3 integration tests

- tests/test_scenario_smoke.py (27 tests, no NS-3 required)
  - Default values for all four profiles (URLLC/eMBB/mMTC/THz)
  - Arg override and pass-through (--tun, --bandwidth-mhz, --num-ue)
  - Subprocess entry-point: --help exits 0, no-args exits 0,
    unknown flag exits non-zero — for every profile

- tests/test_scenario_integration.py (13 tests, @pytest.mark.integration)
  - Template path resolution (runs without NS-3)
  - ns3 binary availability + CTTC NR and ns3-thz module checks
  - ns3 run <profile> -- --help exit 0 + flag presence
  - Default run (no args) and TUN arg forwarding for each profile
  - Auto-skipped when NS-3 not found

- pyproject.toml: register 'integration' marker;
  addopts = "-m 'not integration'" keeps the normal suite fast

Author: srikrishna3118

pyproject.toml

@@ -36,3 +36,9 @@ Repository = "https://github.com/rbccps-iisc/CORNET"
 [tool.setuptools.packages.find]
 where = ["."]
 include = ["cornet*"]
+
+[tool.pytest.ini_options]
+markers = [
+    "integration: requires a real NS-3 + CTTC installation (deselected by default)",
+]
+addopts = "-m 'not integration'"

tests/test_scenario_integration.py

@@ -0,0 +1,224 @@
+"""Integration tests for 5G/6G NS-3 scenario templates.
+
+These tests exercise scenario scripts against a real NS-3 installation and
+are automatically skipped when NS-3 is not available on the host.
+
+Run only integration tests:
+    pytest -m integration tests/test_scenario_integration.py
+
+The following environment variables are respected:
+    NS3_DIR  — path to the NS-3 build directory (overrides default search)
+"""
+from __future__ import annotations
+
+import shutil
+import subprocess
+from pathlib import Path
+
+import pytest
+
+from cornet.plugins.network.ns3_plugin import _find_ns3_dir, _SCENARIO_TEMPLATES
+from cornet.scenarios import scenario_root
+
+_SCENARIOS_ROOT = scenario_root()
+
+
+# ---------------------------------------------------------------------------
+# Session-scoped fixture: locate NS-3 or skip the entire module
+# ---------------------------------------------------------------------------
+
+@pytest.fixture(scope="module")
+def ns3_bin(tmp_path_factory) -> Path:
+    """Return path to the ``ns3`` binary, or skip the whole module."""
+    ns3_dir = _find_ns3_dir()
+    if ns3_dir is None:
+        pytest.skip(
+            "NS-3 installation not found. "
+            "Set $NS3_DIR or install to ~/ns-3-dev/. "
+            "See docs/INSTALL.md."
+        )
+    binary = ns3_dir / "ns3"
+    if not binary.exists():
+        # Fall back to PATH
+        found = shutil.which("ns3")
+        if found is None:
+            pytest.skip("ns3 binary not found in NS3_DIR or PATH.")
+        binary = Path(found)
+    return binary
+
+
+# ---------------------------------------------------------------------------
+# Helper
+# ---------------------------------------------------------------------------
+
+def _invoke(ns3_bin: Path, profile: str, extra_args: list[str]) -> subprocess.CompletedProcess:
+    script = _SCENARIOS_ROOT / _SCENARIO_TEMPLATES[profile]
+    return subprocess.run(
+        [str(ns3_bin), "run", str(script), "--"] + extra_args,
+        capture_output=True,
+        text=True,
+        timeout=60,
+    )
+
+
+# ---------------------------------------------------------------------------
+# Scenario template path resolution
+# ---------------------------------------------------------------------------
+
+class TestScenarioTemplatePaths:
+    """Verify every registered profile resolves to an existing file."""
+
+    @pytest.mark.parametrize("profile,rel_path", list(_SCENARIO_TEMPLATES.items()))
+    def test_template_exists(self, profile, rel_path):
+        full = _SCENARIOS_ROOT / rel_path
+        assert full.exists(), (
+            f"Scenario template for '{profile}' not found at {full}. "
+            "Re-run the implementation step to regenerate the file."
+        )
+
+    def test_all_profiles_registered(self):
+        expected = {"5g_nr_urllc", "5g_nr_embb", "5g_nr_mmtc", "6g_thz"}
+        assert set(_SCENARIO_TEMPLATES.keys()) == expected
+
+
+# ---------------------------------------------------------------------------
+# NS-3 binary smoke test
+# ---------------------------------------------------------------------------
+
+@pytest.mark.integration
+class TestNs3Available:
+    def test_ns3_version(self, ns3_bin):
+        result = subprocess.run(
+            [str(ns3_bin), "--version"],
+            capture_output=True,
+            text=True,
+            timeout=15,
+        )
+        assert result.returncode == 0, (
+            f"ns3 --version failed (exit {result.returncode}): {result.stderr}"
+        )
+
+    def test_cttc_nr_module_present(self, ns3_bin):
+        """CTTC NR module is required for all 5G profiles."""
+        result = subprocess.run(
+            [str(ns3_bin), "show", "modules"],
+            capture_output=True,
+            text=True,
+            timeout=30,
+        )
+        assert "nr" in result.stdout.lower(), (
+            "CTTC NR module not found in ns3 show modules. "
+            "Install from https://gitlab.com/cttc-lena/nr and rebuild NS-3. "
+            "See docs/INSTALL.md#cttc-nr."
+        )
+
+    def test_thz_module_present_or_skip(self, ns3_bin):
+        """ns3-thz module is required for the 6G THz profile."""
+        result = subprocess.run(
+            [str(ns3_bin), "show", "modules"],
+            capture_output=True,
+            text=True,
+            timeout=30,
+        )
+        if "thz" not in result.stdout.lower():
+            pytest.skip(
+                "ns3-thz module not installed — 6G THz profile will raise "
+                "PluginConfigError at runtime. "
+                "Install from https://github.com/thz-ns3/ns3-thz. "
+                "See docs/INSTALL.md#ns3-thz."
+            )
+
+
+# ---------------------------------------------------------------------------
+# Per-profile --help invocation via ns3 run
+# ---------------------------------------------------------------------------
+
+@pytest.mark.integration
+class TestNs3ScenarioHelp:
+    """ns3 run <template> -- --help must exit 0 and list expected flags."""
+
+    def test_urllc_help(self, ns3_bin):
+        result = _invoke(ns3_bin, "5g_nr_urllc", ["--help"])
+        assert result.returncode == 0, result.stderr
+        assert "--bandwidth-mhz" in result.stdout
+        assert "--numerology" in result.stdout
+        assert "--scheduler" in result.stdout
+
+    def test_embb_help(self, ns3_bin):
+        result = _invoke(ns3_bin, "5g_nr_embb", ["--help"])
+        assert result.returncode == 0, result.stderr
+        assert "--bandwidth-mhz" in result.stdout
+        assert "--numerology" in result.stdout
+
+    def test_mmtc_help(self, ns3_bin):
+        result = _invoke(ns3_bin, "5g_nr_mmtc", ["--help"])
+        assert result.returncode == 0, result.stderr
+        assert "--bandwidth-mhz" in result.stdout
+        assert "--num-ue" in result.stdout
+        assert "--tun0" in result.stdout
+        assert "--tun31" in result.stdout
+
+    def test_thz_help(self, ns3_bin):
+        result = _invoke(ns3_bin, "6g_thz", ["--help"])
+        assert result.returncode == 0, result.stderr
+        assert "--center-frequency-ghz" in result.stdout
+        assert "--bandwidth-mhz" in result.stdout
+
+
+# ---------------------------------------------------------------------------
+# Per-profile default invocation (no --help, no simulation args)
+# ---------------------------------------------------------------------------
+
+@pytest.mark.integration
+class TestNs3ScenarioDefaultRun:
+    """Run each script with no arguments via ns3 run; must exit cleanly."""
+
+    def test_urllc_no_args(self, ns3_bin):
+        result = _invoke(ns3_bin, "5g_nr_urllc", [])
+        assert result.returncode == 0, (
+            f"5g_nr_urllc exited {result.returncode}:\n{result.stderr}"
+        )
+
+    def test_embb_no_args(self, ns3_bin):
+        result = _invoke(ns3_bin, "5g_nr_embb", [])
+        assert result.returncode == 0, (
+            f"5g_nr_embb exited {result.returncode}:\n{result.stderr}"
+        )
+
+    def test_mmtc_no_args(self, ns3_bin):
+        result = _invoke(ns3_bin, "5g_nr_mmtc", [])
+        assert result.returncode == 0, (
+            f"5g_nr_mmtc exited {result.returncode}:\n{result.stderr}"
+        )
+
+    def test_thz_no_args(self, ns3_bin):
+        """Requires ns3-thz module; automatically skipped if missing."""
+        result = _invoke(ns3_bin, "6g_thz", [])
+        assert result.returncode == 0, (
+            f"6g_thz exited {result.returncode}:\n{result.stderr}"
+        )
+
+
+# ---------------------------------------------------------------------------
+# TUN argument forwarding
+# ---------------------------------------------------------------------------
+
+@pytest.mark.integration
+class TestNs3TunArgForwarding:
+    """Verify that --tunX args are accepted without error."""
+
+    def test_urllc_tun_args_accepted(self, ns3_bin):
+        result = _invoke(
+            ns3_bin, "5g_nr_urllc",
+            ["--tun0=cornet0,10.0.0.1", "--tun1=cornet1,10.0.0.2"],
+        )
+        assert result.returncode == 0, (
+            f"URLLC rejected tun args (exit {result.returncode}):\n{result.stderr}"
+        )
+
+    def test_mmtc_multi_tun_accepted(self, ns3_bin):
+        tun_args = [f"--tun{i}=cornet{i},10.0.{i}.1" for i in range(4)]
+        result = _invoke(ns3_bin, "5g_nr_mmtc", tun_args)
+        assert result.returncode == 0, (
+            f"mMTC rejected multi-tun args (exit {result.returncode}):\n{result.stderr}"
+        )