fix(incarnation-sapere): validate chemotaxis argument explicitly (#5326)

Author: DanySK

alchemist-incarnation-sapere/src/main/java/it/unibo/alchemist/model/sapere/actions/SAPEREChemotaxis.java

@@ -54,10 +54,9 @@ public SAPEREChemotaxis(
             final int idPosition
     ) {
         super(environment, node, response);
-        /*
-         * Thanks Java, for not having unsigned primitives! -.-
-         */
-        assert idPosition >= 0 : "Argument number must be positive";
+        if (idPosition < 0) {
+            throw new IllegalArgumentException("idPosition must be non-negative, but was: " + idPosition);
+        }
         this.response = response;
         this.gradient = gradient;
         this.idPosition = idPosition;

alchemist-incarnation-sapere/src/test/kotlin/it/unibo/alchemist/model/sapere/TestSAPEREChemotaxis.kt

@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2010-2025, Danilo Pianini and contributors
+ * listed, for each module, in the respective subproject's build.gradle.kts file.
+ *
+ * This file is part of Alchemist, and is distributed under the terms of the
+ * GNU General Public License, with a linking exception,
+ * as described in the file LICENSE in the Alchemist distribution's top directory.
+ */
+package it.unibo.alchemist.model.sapere
+
+import io.kotest.assertions.throwables.shouldThrow
+import io.kotest.core.spec.style.StringSpec
+import io.kotest.matchers.string.shouldContain
+import it.unibo.alchemist.model.environments.Continuous2DEnvironment
+import it.unibo.alchemist.model.incarnations.SAPEREIncarnation
+import it.unibo.alchemist.model.positions.Euclidean2DPosition
+import it.unibo.alchemist.model.sapere.actions.SAPEREChemotaxis
+import it.unibo.alchemist.model.sapere.nodes.LsaNode
+
+class TestSAPEREChemotaxis :
+    StringSpec(
+        {
+            "SAPEREChemotaxis constructor should throw IllegalArgumentException for negative idPosition" {
+                val incarnation = SAPEREIncarnation<Euclidean2DPosition>()
+                val environment = Continuous2DEnvironment<List<ILsaMolecule>>(incarnation)
+                val node = LsaNode(environment)
+                val response = incarnation.createMolecule("response")
+                val gradient = incarnation.createMolecule("gradient, Dest")
+                val invalidPosition = -1
+                val exception = shouldThrow<IllegalArgumentException> {
+                    SAPEREChemotaxis(environment, node, response, gradient, invalidPosition)
+                }
+                exception.message shouldContain "idPosition"
+                exception.message shouldContain invalidPosition.toString()
+            }
+        },
+    )