improved pytest logic and code coherence

Author: GioeleB00

documentation/backend_documentation/input_structure_for_the_simulation.md

@@ -6,7 +6,7 @@ This contract brings together three distinct but interconnected layers of config
 
 1.  **`rqs_input` (`RqsGeneratorInput`)**: Defines the **workload profile**—how many users are active and how frequently they generate requests.
 2.  **`topology_graph` (`TopologyGraph`)**: Describes the **system's architecture**—its components, resources, and the network connections between them.
-3.  **`settings` (`SimulationSettings`)**: Configures **global simulation parameters**, such as total runtime and which metrics to collect.
+3.  **`sim_settings` (`SimulationSettings`)**: Configures **global simulation parameters**, such as total runtime and which metrics to collect.
 
 This layered design decouples the *what* (the system topology) from the *how* (the traffic pattern and simulation control), allowing for modular and reusable configurations. Adherence to our validation-first philosophy means every payload is rigorously parsed against this schema. By using a controlled vocabulary of `Enums` and the power of Pydantic, we guarantee that any malformed or logically inconsistent input is rejected upfront with clear, actionable errors, ensuring the simulation engine operates only on perfectly valid data.
 
@@ -170,8 +170,20 @@ This final component configures the simulation's execution parameters and, criti
 class SimulationSettings(BaseModel):
     """Global parameters that apply to the whole run."""
     total_simulation_time: int = Field(...)
-    enabled_sample_metrics: set[SampledMetricName]
-    enabled_event_metrics: set[EventMetricName]
+    enabled_sample_metrics: set[SampledMetricName] = Field(
+        default_factory=lambda: {
+            SampledMetricName.READY_QUEUE_LEN,
+            SampledMetricName.CORE_BUSY,
+            SampledMetricName.RAM_IN_USE,
+        },
+        description="Which time‑series KPIs to collect by default.",
+    )
+    enabled_event_metrics: set[EventMetricName] = Field(
+        default_factory=lambda: {
+            EventMetricName.RQS_LATENCY,
+        },
+        description="Which per‑event KPIs to collect by default.",
+    )
 ```
 
 | Field | Type | Purpose & Validation |
@@ -180,6 +192,7 @@ class SimulationSettings(BaseModel):
 | `enabled_sample_metrics` | `set[SampledMetricName]` | A set of metrics to be sampled at fixed intervals, creating a time-series (e.g., `"ready_queue_len"`, `"ram_in_use"`). |
 | `enabled_event_metrics` | `set[EventMetricName]` | A set of metrics recorded only when specific events occur, with no time-series (e.g., `"rqs_latency"`, `"llm_cost"`). |
 
+We add standard default value for the metrics in case they will be omitted
 ---
 
 #### **Design Rationale: Pre-validated, On-Demand Metrics for Robust and Efficient Collection**

src/app/core/event_samplers/gaussian_poisson.py

@@ -22,7 +22,7 @@
 
 def gaussian_poisson_sampling(
     input_data: RqsGeneratorInput,
-    settings: SimulationSettings,
+    sim_settings: SimulationSettings,
     *,
     rng: np.random.Generator | None = None,
 ) -> Generator[float, None, None]:
@@ -41,7 +41,7 @@ def gaussian_poisson_sampling(
     """
     rng = rng or np.random.default_rng()
 
-    simulation_time = settings.total_simulation_time
+    simulation_time = sim_settings.total_simulation_time
     user_sampling_window = input_data.user_sampling_window
 
     # λ_u : mean concurrent users per window

src/app/core/event_samplers/poisson_poisson.py

@@ -19,7 +19,7 @@
 
 def poisson_poisson_sampling(
     input_data: RqsGeneratorInput,
-    settings: SimulationSettings,
+    sim_settings: SimulationSettings,
     *,
     rng: np.random.Generator | None = None,
 ) ->  Generator[float, None, None]:
@@ -38,7 +38,7 @@ def poisson_poisson_sampling(
     """
     rng = rng or np.random.default_rng()
 
-    simulation_time = settings.total_simulation_time
+    simulation_time = sim_settings.total_simulation_time
     user_sampling_window = input_data.user_sampling_window
 
     # λ_u : mean concurrent users per window

src/app/core/simulation/requests_generator.py

@@ -22,7 +22,7 @@
 
 def requests_generator(
     input_data: RqsGeneratorInput,
-    settings: SimulationSettings,
+    sim_settings: SimulationSettings,
     *,
     rng: np.random.Generator | None = None,
 ) -> Generator[float, None, None]:
@@ -43,14 +43,14 @@ def requests_generator(
         #Gaussian-Poisson model
         return gaussian_poisson_sampling(
             input_data=input_data,
-            settings=settings,
+            sim_settings=sim_settings,
             rng=rng,
 
         )
 
     # Poisson + Poisson
     return poisson_poisson_sampling(
         input_data=input_data,
-        settings=settings,
+        sim_settings=sim_settings,
         rng=rng,
     )

src/app/core/simulation/simulation_run.py

@@ -27,24 +27,19 @@ def run_simulation(
     rng: np.random.Generator,
 ) -> SimulationOutput:
     """Simulation executor in Simpy"""
-    settings = input_data.settings
-    simulation_time = settings.total_simulation_time
-    # pydantic in the validation assign a value and mypy is not
-    # complaining because a None cannot be compared in the loop
-    # to a float
-    assert simulation_time is not None
+    sim_settings = input_data.sim_settings
 
     requests_generator_input = input_data.rqs_input
 
     gaps: Generator[float, None, None] = requests_generator(
         requests_generator_input,
-        settings,
+        sim_settings,
         rng=rng)
     env = simpy.Environment()
 
 
     total_request_per_time_period = {
-        "simulation_time": simulation_time,
+        "simulation_time": sim_settings.total_simulation_time,
         "total_requests": 0,
         }
 
@@ -56,7 +51,7 @@ def arrival_process(
             total_request_per_time_period["total_requests"] += 1
 
     env.process(arrival_process(env))
-    env.run(until=simulation_time)
+    env.run(until=sim_settings.total_simulation_time)
 
     return SimulationOutput(
         total_requests=total_request_per_time_period,

src/app/schemas/full_simulation_input.py

@@ -12,4 +12,4 @@ class SimulationPayload(BaseModel):
 
     rqs_input: RqsGeneratorInput
     topology_graph: TopologyGraph
-    settings: SimulationSettings
+    sim_settings: SimulationSettings

src/app/schemas/simulation_settings_input.py

@@ -2,7 +2,7 @@
 
 from pydantic import BaseModel, Field
 
-from app.config.constants import TimeDefaults
+from app.config.constants import EventMetricName, SampledMetricName, TimeDefaults
 
 
 class SimulationSettings(BaseModel):
@@ -13,3 +13,19 @@ class SimulationSettings(BaseModel):
         ge=TimeDefaults.MIN_SIMULATION_TIME,
         description="Simulation horizon in seconds.",
     )
+
+    enabled_sample_metrics: set[SampledMetricName] = Field(
+        default_factory=lambda: {
+            SampledMetricName.READY_QUEUE_LEN,
+            SampledMetricName.CORE_BUSY,
+            SampledMetricName.RAM_IN_USE,
+        },
+        description="Which time-series KPIs to collect by default.",
+    )
+    enabled_event_metrics: set[EventMetricName] = Field(
+        default_factory=lambda: {
+            EventMetricName.RQS_LATENCY,
+        },
+        description="Which per-event KPIs to collect by default.",
+    )
+

tests/conftest.py

@@ -10,6 +10,8 @@
 from alembic.config import Config
 from dotenv import load_dotenv
 from fastapi.testclient import TestClient
+from numpy.random import Generator as NpGenerator
+from numpy.random import default_rng
 from sqlalchemy.ext.asyncio import (
     AsyncEngine,
     AsyncSession,
@@ -18,9 +20,23 @@
 )
 from sqlalchemy_utils import create_database, database_exists, drop_database
 
+from app.config.constants import (
+    EventMetricName,
+    SampledMetricName,
+    TimeDefaults,
+)
 from app.config.settings import settings
 from app.db.session import get_db
 from app.main import app
+from app.schemas.full_simulation_input import SimulationPayload
+from app.schemas.random_variables_config import RVConfig
+from app.schemas.requests_generator_input import RqsGeneratorInput
+from app.schemas.simulation_settings_input import SimulationSettings
+from app.schemas.system_topology_schema.full_system_topology_schema import (
+    Client,
+    TopologyGraph,
+    TopologyNodes,
+)
 
 # Load test environment variables from .env.test
 ENV_PATH = Path(__file__).resolve().parents[1] / "docker_fs" / ".env.test"
@@ -121,3 +137,102 @@ async def db_session(async_engine: AsyncEngine) -> AsyncGenerator[AsyncSession,
         await transaction.rollback()
         # Close the connection
         await connection.close()
+
+# ============================================================================
+# STANDARD CONFIGURATION FOR INPUT VARIABLES
+# ============================================================================
+
+# ---------------------------------------------------------------------------
+# RNG
+# ---------------------------------------------------------------------------
+
+
+@pytest.fixture(scope="session")
+def rng() -> NpGenerator:
+    """Deterministic NumPy RNG shared across tests (seed=0)."""
+    return default_rng(0)
+
+
+# ---------------------------------------------------------------------------
+# Metrics sets
+# ---------------------------------------------------------------------------
+
+
+@pytest.fixture(scope="session")
+def enabled_sample_metrics() -> set[SampledMetricName]:
+    """Default sample-level KPIs tracked in most tests."""
+    return {
+        SampledMetricName.READY_QUEUE_LEN,
+        SampledMetricName.RAM_IN_USE,
+    }
+
+
+@pytest.fixture(scope="session")
+def enabled_event_metrics() -> set[EventMetricName]:
+    """Default event-level KPIs tracked in most tests."""
+    return {EventMetricName.RQS_LATENCY}
+
+
+# ---------------------------------------------------------------------------
+# Global simulation settings
+# ---------------------------------------------------------------------------
+
+
+@pytest.fixture
+def sim_settings(
+    enabled_sample_metrics: set[SampledMetricName],
+    enabled_event_metrics: set[EventMetricName],
+) -> SimulationSettings:
+    """A minimal `SimulationSettings` instance for unit tests."""
+    return SimulationSettings(
+        total_simulation_time=TimeDefaults.MIN_SIMULATION_TIME,
+        enabled_sample_metrics=enabled_sample_metrics,
+        enabled_event_metrics=enabled_event_metrics,
+    )
+
+
+# ---------------------------------------------------------------------------
+# Traffic profile
+# ---------------------------------------------------------------------------
+
+
+@pytest.fixture
+def rqs_input() -> RqsGeneratorInput:
+    """`RqsGeneratorInput` with 1 user and 2 req/min for quick tests."""
+    return RqsGeneratorInput(
+        avg_active_users=RVConfig(mean=1.0),
+        avg_request_per_minute_per_user=RVConfig(mean=2.0),
+        user_sampling_window=TimeDefaults.USER_SAMPLING_WINDOW,
+    )
+
+
+# ---------------------------------------------------------------------------
+# Minimal topology (one client, no servers, no edges)
+# ---------------------------------------------------------------------------
+
+
+@pytest.fixture
+def topology_minimal() -> TopologyGraph:
+    """Valid topology with a single client and zero servers/edges."""
+    client = Client(id="client-1")
+    nodes = TopologyNodes(servers=[], client=client)
+    return TopologyGraph(nodes=nodes, edges=[])
+
+
+# ---------------------------------------------------------------------------
+# Full simulation payload
+# ---------------------------------------------------------------------------
+
+
+@pytest.fixture
+def payload_base(
+    rqs_input: RqsGeneratorInput,
+    sim_settings: SimulationSettings,
+    topology_minimal: TopologyGraph,
+) -> SimulationPayload:
+    """End-to-end payload used by high-level simulation tests."""
+    return SimulationPayload(
+        rqs_input=rqs_input,
+        topology_graph=topology_minimal,
+        sim_settings=sim_settings,
+    )