anchor.diff:              "${errors.map((e) => e.plainTextFormatted.first).toList()}");
         }
         Uri dillFileUri = toTestUri("${test.description.shortName}.dill");
  +      Uri dillFileNoNNBDUri =
  +          toTestUri("${test.description.shortName}.no.nnbd.dill");
         Uint8List dillData = await serializeComponent(component);
         context.fileSystem.entityForUri(dillFileUri).writeAsBytesSync(dillData);
         Set<Uri> beforeFuzzedLibraries = context.fuzzedLibraries.toSet();
  -      await compileExpression(
  -          test, sourceCompiler, sourceCompilerResult, context);
  +      IncrementalCompiler? sourceCompilerNoNNBD;
  +      if (context.fuzz) {
  +        sourceCompilerNoNNBD =
  +            new IncrementalCompiler(context.compilerContextNoNNBD);
  +        IncrementalCompilerResult sourceCompilerNoNNBDResult =
  +            await sourceCompilerNoNNBD
  +                .computeDelta(entryPoints: [test.entryPoint]);
  +        Component componentNoNNBD = sourceCompilerNoNNBDResult.component;
  +        Uint8List dillDataNoNNBD = await serializeComponent(componentNoNNBD);
  +        context.fileSystem
  +            .entityForUri(dillFileNoNNBDUri)
  +            .writeAsBytesSync(dillDataNoNNBD);
  +        context.takeErrors();
  +      }
  +      await compileExpression(test, sourceCompiler, sourceCompilerNoNNBD,
  +          sourceCompilerResult, context);
   
         IncrementalCompiler dillCompiler =
             new IncrementalCompiler(context.compilerContext, dillFileUri);
  
positive.code:     }
    }
  
    Future<void> fuzzTryCompile(IncrementalCompiler compiler, String expression,
        Uri libraryUri, String? className, bool isStatic, Context context) async {
      context.fuzzCompiles++;
      print("Fuzz compile #${context.fuzzCompiles} "
          "('$expression' in $libraryUri $className)");
      Procedure? compiledProcedure = await compiler.compileExpression(
        expression,
        {},
        [],
        "debugExpr",
        libraryUri,
        className: className,
        isStatic: isStatic,
      );
      context.takeErrors();
      if (compiledProcedure != null) {
        // Confirm we can serialize generated procedure.
        List<int> list = serializeProcedure(compiledProcedure);
        assert(list.length > 0);
      }
    }
  
  
negative.code:     if (className != null && !m.isInstanceMember) {
        await fuzzTryCompile(
            compiler,
            compilerNoNNBD,
            "() { var x = $className.$expression.toString(); x == '42'; }()",
            libraryUri,
            null,
  