Use assertions for compiler option preconditions

Treat the compiler options snapshot as an internal contract: the only producer normalizes null define symbols before construction. Use the project's assertion convention for that programmer error and keep the remaining tests focused on snapshot behavior.

Author: hatayama

Assets/Tests/Editor/DynamicCodeToolTests/RoslynCompilerOptionsTests.cs

@@ -47,15 +47,5 @@ public void Constructor_WithEmptyDefineSymbols_CapturesEmptySnapshot()
             Assert.That(options.AllowUnsafeCode, Is.False);
         }
 
-        /// <summary>
-        /// Verifies a null define-symbol collection fails fast at the snapshot boundary.
-        /// </summary>
-        [Test]
-        public void Constructor_WithNullDefineSymbols_ThrowsArgumentNullException()
-        {
-            Assert.That(
-                () => new RoslynCompilerOptions(null, false),
-                Throws.ArgumentNullException);
-        }
     }
 }

Packages/src/Editor/FirstPartyTools/ExecuteDynamicCode/DynamicCompilation/RoslynCompilerOptions.cs

@@ -1,5 +1,5 @@
-using System;
 using System.Collections.Generic;
+using UnityEngine;
 
 namespace io.github.hatayama.UnityCliLoop.FirstPartyTools
 {
@@ -19,10 +19,7 @@ public RoslynCompilerOptions(
             IReadOnlyCollection<string> defineSymbols,
             bool allowUnsafeCode)
         {
-            if (defineSymbols == null)
-            {
-                throw new ArgumentNullException(nameof(defineSymbols));
-            }
+            Debug.Assert(defineSymbols != null, "defineSymbols must not be null");
 
             List<string> filteredDefineSymbols = new(defineSymbols.Count);
             foreach (string defineSymbol in defineSymbols)