fix(mac): propagate AltTester define symbols into Unity 6 Build Profile

Unity 6 Build Profiles can override scripting define symbols.
On macOS Unity 6 this caused AltTester runtime scripts to be excluded,
leaving missing-script errors on AltTesterPrefab and no server listening.

For AltTester builds, mirror the current Standalone define symbols into the
BuildProfile's scripting defines before building, then restore afterwards.

Author: rodrigo-fournier-immutable

sample/Assets/Editor/MacBuilderUnity6.cs

@@ -7,6 +7,7 @@
 using AltTester.AltTesterUnitySDK.Editor;
 using System;
 using System.Linq;
+using System.Collections.Generic;
 using AltTester.AltTesterUnitySDK.Commands;
 using AltTester.AltTesterSDK.Driver;
 using TMPro;
@@ -60,6 +61,30 @@ private static void BuildPlayer(string defaultBuildPath, bool setupForAltTester
 
             Debug.Log($"Using Build Profile: {buildProfile.name}");
 
+            // Unity 6 Build Profiles can override scripting defines. If we only mutate
+            // PlayerSettings, AltTester runtime scripts may be excluded from the build
+            // (leading to missing-script errors and no AltTester server listening).
+            // For AltTester builds, temporarily mirror the current Standalone define
+            // symbols onto the BuildProfile's scripting defines.
+            string[] originalProfileDefines = Array.Empty<string>();
+            if (setupForAltTester)
+            {
+                originalProfileDefines = GetBuildProfileDefines(buildProfile);
+
+                // Capture the current Standalone define symbols after SetupAltTester()
+                // has added AltTester + IMMUTABLE_E2E_TESTING.
+                string defineSymbols = PlayerSettings.GetScriptingDefineSymbolsForGroup(BuildTargetGroup.Standalone);
+                var desired = defineSymbols
+                    .Split(';')
+                    .Select(s => s.Trim())
+                    .Where(s => !string.IsNullOrEmpty(s))
+                    .Distinct()
+                    .ToArray();
+
+                SetBuildProfileDefines(buildProfile, MergeDefines(originalProfileDefines, desired));
+                Debug.Log($"Applied {desired.Length} define symbols to BuildProfile for AltTester build.");
+            }
+
             BuildPlayerWithProfileOptions options = new BuildPlayerWithProfileOptions
             {
                 buildProfile = buildProfile,
@@ -82,6 +107,11 @@ private static void BuildPlayer(string defaultBuildPath, bool setupForAltTester
                 EditorApplication.Exit(1);
             }
 
+            if (setupForAltTester)
+            {
+                // Restore original profile defines to avoid dirtying the repo locally.
+                SetBuildProfileDefines(buildProfile, originalProfileDefines);
+            }
 
             if (setupForAltTester)
             {
@@ -171,6 +201,59 @@ private static void SetupAltTester(string[] scenes)
         AltBuilder.InsertAltInScene(scenes[0], instrumentationSettings);
     }
 
+    private static string[] GetBuildProfileDefines(BuildProfile buildProfile)
+    {
+        var so = new SerializedObject(buildProfile);
+        var prop = so.FindProperty("m_ScriptingDefines");
+        if (prop == null || !prop.isArray) return Array.Empty<string>();
+        var list = new List<string>(prop.arraySize);
+        for (int i = 0; i < prop.arraySize; i++)
+        {
+            var el = prop.GetArrayElementAtIndex(i);
+            if (el != null && !string.IsNullOrEmpty(el.stringValue))
+            {
+                list.Add(el.stringValue);
+            }
+        }
+        return list.ToArray();
+    }
+
+    private static string[] MergeDefines(IEnumerable<string> a, IEnumerable<string> b)
+    {
+        var set = new HashSet<string>(StringComparer.Ordinal);
+        foreach (var s in a ?? Array.Empty<string>()) if (!string.IsNullOrEmpty(s)) set.Add(s);
+        foreach (var s in b ?? Array.Empty<string>()) if (!string.IsNullOrEmpty(s)) set.Add(s);
+        return set.ToArray();
+    }
+
+    private static void SetBuildProfileDefines(BuildProfile buildProfile, IEnumerable<string> defines)
+    {
+        var so = new SerializedObject(buildProfile);
+        var prop = so.FindProperty("m_ScriptingDefines");
+        if (prop == null || !prop.isArray)
+        {
+            Debug.LogWarning("BuildProfile does not expose m_ScriptingDefines; cannot apply defines.");
+            return;
+        }
+
+        prop.ClearArray();
+        int idx = 0;
+        if (defines != null)
+        {
+            foreach (var d in defines)
+            {
+                if (string.IsNullOrEmpty(d)) continue;
+                prop.InsertArrayElementAtIndex(idx);
+                prop.GetArrayElementAtIndex(idx).stringValue = d;
+                idx++;
+            }
+        }
+
+        so.ApplyModifiedPropertiesWithoutUndo();
+        EditorUtility.SetDirty(buildProfile);
+        AssetDatabase.SaveAssets();
+    }
+
     public static void RemoveAltFromScene(string scene)
     {
         Debug.Log("Removing AltTesterPrefab from the [" + scene + "] scene.");