fix: address flutter_tools test failures

- build_test.dart: GenSnapshot now requires a `fileSystem` parameter (added by
  this branch for the analyze_snapshot probe path); pass `MemoryFileSystem.test()`
  to the test constructor.
- macos_test.dart: the DD pass is gated on SHOREBIRD_DD_MAX_BYTES, which isn't
  set in the test environment, so neither arm64 nor x86_64 has an extra async
  hop before gen_snapshot. With concurrent Future.wait the archs now reach
  gen_snapshot in iteration order (arm64 first, x86_64 second). Update the
  expected command sequence and the explanatory comment to match.

Author: bdero

packages/flutter_tools/test/general.shard/base/build_test.dart

@@ -63,6 +63,7 @@ void main() {
         artifacts: artifacts,
         logger: logger,
         processManager: processManager,
+        fileSystem: MemoryFileSystem.test(),
       );
     });
 

packages/flutter_tools/test/general.shard/build_system/targets/macos_test.dart

@@ -889,64 +889,66 @@ flavors:
           .createSync(recursive: true);
 
       final build = environment.buildDir.path;
-      // Because arm64 goes through an async _computeDDTable() check (even
-      // though it returns immediately when analyze_snapshot is absent), x86_64
-      // reaches gen_snapshot first when both run concurrently via Future.wait.
-      // After that first yield, the two builds interleave at each await point.
+      // Both archs go through the same code path now (the DD-pass is gated on
+      // SHOREBIRD_DD_MAX_BYTES which isn't set in this test), so neither
+      // architecture has an extra async hop. With concurrent Future.wait, the
+      // archs reach gen_snapshot in iteration order: arm64 first
+      // (`kDarwinArchs = 'arm64 x86_64'`), x86_64 second. They then
+      // interleave at each subsequent await point in the same order.
       processManager.addCommands(<FakeCommand>[
-        // x86_64 gen_snapshot runs first (arm64 is still in _computeDDTable).
+        // arm64 gen_snapshot runs first (iteration order).
         FakeCommand(
           command: <String>[
-            'Artifact.genSnapshotX64.TargetPlatform.darwin.release',
+            'Artifact.genSnapshotArm64.TargetPlatform.darwin.release',
             '--deterministic',
             ...linkInfoArgsFor(build),
             '--snapshot_kind=app-aot-assembly',
-            '--assembly=${environment.buildDir.childFile('x86_64/snapshot_assembly.S').path}',
+            '--assembly=${environment.buildDir.childFile('arm64/snapshot_assembly.S').path}',
             environment.buildDir.childFile('app.dill').path,
           ],
         ),
-        // arm64 gen_snapshot runs next.
+        // x86_64 gen_snapshot runs next.
         FakeCommand(
           command: <String>[
-            'Artifact.genSnapshotArm64.TargetPlatform.darwin.release',
+            'Artifact.genSnapshotX64.TargetPlatform.darwin.release',
             '--deterministic',
             ...linkInfoArgsFor(build),
             '--snapshot_kind=app-aot-assembly',
-            '--assembly=${environment.buildDir.childFile('arm64/snapshot_assembly.S').path}',
+            '--assembly=${environment.buildDir.childFile('x86_64/snapshot_assembly.S').path}',
             environment.buildDir.childFile('app.dill').path,
           ],
         ),
-        // From here on the two builds interleave: x86_64 then arm64 at each step.
+        // From here on the two builds interleave: arm64 then x86_64 at each step.
         FakeCommand(
           command: <String>[
             'xcrun',
             'cc',
             '-arch',
-            'x86_64',
+            'arm64',
             '-c',
-            environment.buildDir.childFile('x86_64/snapshot_assembly.S').path,
+            environment.buildDir.childFile('arm64/snapshot_assembly.S').path,
             '-o',
-            environment.buildDir.childFile('x86_64/snapshot_assembly.o').path,
+            environment.buildDir.childFile('arm64/snapshot_assembly.o').path,
           ],
         ),
         FakeCommand(
           command: <String>[
             'xcrun',
             'cc',
             '-arch',
-            'arm64',
+            'x86_64',
             '-c',
-            environment.buildDir.childFile('arm64/snapshot_assembly.S').path,
+            environment.buildDir.childFile('x86_64/snapshot_assembly.S').path,
             '-o',
-            environment.buildDir.childFile('arm64/snapshot_assembly.o').path,
+            environment.buildDir.childFile('x86_64/snapshot_assembly.o').path,
           ],
         ),
         FakeCommand(
           command: <String>[
             'xcrun',
             'clang',
             '-arch',
-            'x86_64',
+            'arm64',
             '-dynamiclib',
             '-Xlinker',
             '-rpath',
@@ -960,16 +962,16 @@ flavors:
             '-install_name',
             '@rpath/App.framework/App',
             '-o',
-            environment.buildDir.childFile('x86_64/App.framework/App').path,
-            environment.buildDir.childFile('x86_64/snapshot_assembly.o').path,
+            environment.buildDir.childFile('arm64/App.framework/App').path,
+            environment.buildDir.childFile('arm64/snapshot_assembly.o').path,
           ],
         ),
         FakeCommand(
           command: <String>[
             'xcrun',
             'clang',
             '-arch',
-            'arm64',
+            'x86_64',
             '-dynamiclib',
             '-Xlinker',
             '-rpath',
@@ -983,46 +985,46 @@ flavors:
             '-install_name',
             '@rpath/App.framework/App',
             '-o',
-            environment.buildDir.childFile('arm64/App.framework/App').path,
-            environment.buildDir.childFile('arm64/snapshot_assembly.o').path,
+            environment.buildDir.childFile('x86_64/App.framework/App').path,
+            environment.buildDir.childFile('x86_64/snapshot_assembly.o').path,
           ],
         ),
         FakeCommand(
           command: <String>[
             'xcrun',
             'dsymutil',
             '-o',
-            environment.buildDir.childFile('x86_64/App.framework.dSYM').path,
-            environment.buildDir.childFile('x86_64/App.framework/App').path,
+            environment.buildDir.childFile('arm64/App.framework.dSYM').path,
+            environment.buildDir.childFile('arm64/App.framework/App').path,
           ],
         ),
         FakeCommand(
           command: <String>[
             'xcrun',
             'dsymutil',
             '-o',
-            environment.buildDir.childFile('arm64/App.framework.dSYM').path,
-            environment.buildDir.childFile('arm64/App.framework/App').path,
+            environment.buildDir.childFile('x86_64/App.framework.dSYM').path,
+            environment.buildDir.childFile('x86_64/App.framework/App').path,
           ],
         ),
         FakeCommand(
           command: <String>[
             'xcrun',
             'strip',
             '-x',
-            environment.buildDir.childFile('x86_64/App.framework/App').path,
+            environment.buildDir.childFile('arm64/App.framework/App').path,
             '-o',
-            environment.buildDir.childFile('x86_64/App.framework/App').path,
+            environment.buildDir.childFile('arm64/App.framework/App').path,
           ],
         ),
         FakeCommand(
           command: <String>[
             'xcrun',
             'strip',
             '-x',
-            environment.buildDir.childFile('arm64/App.framework/App').path,
+            environment.buildDir.childFile('x86_64/App.framework/App').path,
             '-o',
-            environment.buildDir.childFile('arm64/App.framework/App').path,
+            environment.buildDir.childFile('x86_64/App.framework/App').path,
           ],
         ),
         FakeCommand(