Analysis request `getReachableSources` (#24893).

pkg/analysis_server/test/integration/protocol_matchers.dart

Index: pkg/analysis_server/test/integration/protocol_matchers.dart
diff --git a/pkg/analysis_server/test/integration/protocol_matchers.dart b/pkg/analysis_server/test/integration/protocol_matchers.dart
index fed0c036d9ff6af410dd26b0e288d3d41289d4dc..a7443ba23adc49f324ba45bb4f436dfd1a3ebc9d 100644
--- a/pkg/analysis_server/test/integration/protocol_matchers.dart
+++ b/pkg/analysis_server/test/integration/protocol_matchers.dart
@@ -153,6 +153,30 @@ final Matcher isAnalysisGetHoverResult = new LazyMatcher(() => new MatchesJsonOb
   }));
 
 /**
+ * analysis.getReachableSources params
+ *
+ * {
+ *   "file": FilePath
+ * }
+ */
+final Matcher isAnalysisGetReachableSourcesParams = new LazyMatcher(() => new MatchesJsonObject(
+  "analysis.getReachableSources params", {
+    "file": isFilePath
+  }));
+
+/**
+ * analysis.getReachableSources result
+ *
+ * {
+ *   "sources": Map<String, List<String>>
+ * }
+ */
+final Matcher isAnalysisGetReachableSourcesResult = new LazyMatcher(() => new MatchesJsonObject(
+  "analysis.getReachableSources result", {
+    "sources": isMapOf(isString, isListOf(isString))
+  }));
+
+/**
  * analysis.getLibraryDependencies params
  */
 final Matcher isAnalysisGetLibraryDependenciesParams = isNull;