Make interactive visualization example optional-dependency-safe for examples verification

examples/visualization/example_interactive_multilayer.py

@@ -33,7 +33,8 @@
     print(" Plotly is available")
 except ImportError:
     print(" Plotly not found. Install with: pip install plotly")
-    exit(1)
+    print(" Skipping interactive visualization example")
+    exit(0)
 
 # Create a multilayer network
 print("\nStep 1: Creating multilayer network...")

tests/test_example_interactive_multilayer.py

@@ -0,0 +1,27 @@
+import os
+import subprocess
+import sys
+from pathlib import Path
+
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+EXAMPLE_FILE = REPO_ROOT / "examples" / "visualization" / "example_interactive_multilayer.py"
+
+
+def test_interactive_multilayer_example_handles_missing_plotly():
+    """Example should not fail the suite when optional plotly dependency is absent."""
+    result = subprocess.run(
+        [sys.executable, str(EXAMPLE_FILE)],
+        cwd=REPO_ROOT,
+        capture_output=True,
+        text=True,
+        timeout=60,
+        env={
+            **os.environ,
+            "PYTHONPATH": str(REPO_ROOT),
+            "FAST_EXAMPLES": "1",
+            "TQDM_DISABLE": "1",
+            "PYTHONWARNINGS": "ignore",
+        },
+    )
+    assert result.returncode == 0, result.stderr or result.stdout