analyzer_utilities: change analysisOptionsContent.include to be a list.

Change-Id: I664a1133ab873e88a1034111b83eb70ac429c9b3
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/426985
Commit-Queue: Samuel Rawlins <srawlins@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
diff --git a/pkg/analysis_server/test/domain_analysis_test.dart b/pkg/analysis_server/test/domain_analysis_test.dart
index 746c44a..bd24263 100644
--- a/pkg/analysis_server/test/domain_analysis_test.dart
+++ b/pkg/analysis_server/test/domain_analysis_test.dart
@@ -2263,7 +2263,7 @@
     // `analysis_options.yaml`.
     newAnalysisOptionsYamlFile(
       join(workspaceRootPath, 'package1', 'nestedFolder1'),
-      analysisOptionsContent(include: '../analysis_options.yaml'),
+      analysisOptionsContent(includes: ['../analysis_options.yaml']),
     );
 
     // Write the single package config at the root that can resolve both
diff --git a/pkg/analyzer_utilities/lib/testing/test_support.dart b/pkg/analyzer_utilities/lib/testing/test_support.dart
index b556674..0e62cb7 100644
--- a/pkg/analyzer_utilities/lib/testing/test_support.dart
+++ b/pkg/analyzer_utilities/lib/testing/test_support.dart
@@ -5,8 +5,7 @@
 /// Returns the content for an analysis options file, specified appropriately
 /// with the given parameter values.
 String analysisOptionsContent({
-  // TODO(srawlins): Change this maybe to a List<String>.
-  String? include,
+  List<String> includes = const [],
   List<String> experiments = const [],
   List<String> legacyPlugins = const [],
   List<String> rules = const [],
@@ -17,8 +16,11 @@
 }) {
   var buffer = StringBuffer();
 
-  if (include != null) {
-    buffer.writeln('include: $include');
+  if (includes.isNotEmpty) {
+    buffer.writeln('include:');
+    for (var include in includes) {
+      buffer.writeln('  - $include');
+    }
   }
 
   buffer.writeln('analyzer:');