Issue 23027. Try to make priority files analyzable.

pkg/analysis_server/test/domain_analysis_test.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library test.domain.analysis;
 
 import 'dart:async';
 
 import 'package:analysis_server/src/analysis_server.dart';
 import 'package:analysis_server/src/constants.dart';
@@ skipping 303 matching lines @@
     });
   }
 
   test_setRoots_packages() {
     // prepare package
     String pkgFile = '/packages/pkgA/libA.dart';
     resourceProvider.newFile(pkgFile, '''
 library lib_a;
 class A {}
 ''');
-    packageMapProvider.packageMap['pkgA'] = [
-      resourceProvider.getResource('/packages/pkgA')
-    ];
+    packageMapProvider.packageMap['pkgA'] =
+        [resourceProvider.getResource('/packages/pkgA')];
     addTestFile('''
 import 'package:pkgA/libA.dart';
 main(A a) {
 }
 ''');
     // create project and wait for analysis
     createProject();
     return waitForTasksFinished().then((_) {
       // if 'package:pkgA/libA.dart' was resolved, then there are no errors
       expect(filesErrors[testFile], isEmpty);
@@ skipping 303 matching lines @@
     // wait for analysis, no results initially
     await waitForTasksFinished();
     expect(filesHighlights[pkgFileA], isNull);
     // subscribe
     addAnalysisSubscription(AnalysisService.HIGHLIGHTS, pkgFileA);
     await server.onAnalysisComplete;
     // there are results
     expect(filesHighlights[pkgFileA], isNotEmpty);
   }
 
+  test_afterAnalysis_packageFile_notUsed() async {
+    String pkgFile = '/packages/pkgA/lib/libA.dart';
+    resourceProvider.newFile(pkgFile, '''
+library lib_a;
+class A {}
+''');
+    packageMapProvider.packageMap = {
+      'pkgA': [(resourceProvider.newFolder('/packages/pkgA/lib'))]
+    };
+    //
+    addTestFile('// no "pkgA" reference');
+    createProject();
+    // wait for analysis, no results initially
+    await waitForTasksFinished();
+    expect(filesHighlights[pkgFile], isNull);
+    // make it a priority file, so make analyzable
+    server.setPriorityFiles('0', [pkgFile]);
+    // subscribe
+    addAnalysisSubscription(AnalysisService.HIGHLIGHTS, pkgFile);
+    await server.onAnalysisComplete;
+    // there are results
+    expect(filesHighlights[pkgFile], isNotEmpty);
+  }
+
   test_afterAnalysis_sdkFile() async {
     String file = '/lib/core/core.dart';
     addTestFile('// no matter');
     createProject();
     // wait for analysis, no results initially
     await waitForTasksFinished();
     expect(filesHighlights[file], isNull);
     // subscribe
     addAnalysisSubscription(AnalysisService.HIGHLIGHTS, file);
     await server.onAnalysisComplete;
     // there are results
     expect(filesHighlights[file], isNotEmpty);
   }
 
   test_beforeAnalysis() async {
     addTestFile('int V = 42;');
     createProject();
     // subscribe
     addAnalysisSubscription(AnalysisService.HIGHLIGHTS, testFile);
     // wait for analysis
     await waitForTasksFinished();
     expect(filesHighlights[testFile], isNotEmpty);
   }
 }