Fix regression for import suggestions

Imports weren't being suggested for implicit source files,
for example files from other analysis roots.

BUG=
R=brianwilkerson@google.com, scheglov@google.com

Review URL: https://codereview.chromium.org/1759333002 .

pkg/analysis_server/lib/src/services/correction/fix_internal.dart

@@ -1528,7 +1528,7 @@ class FixProcessor {
         }
         // prepare LibraryElement
         LibraryElement libraryElement =
-            context.getResult(librarySource, LIBRARY_ELEMENT8);
+            context.getResult(librarySource, LIBRARY_ELEMENT4);
         if (libraryElement == null) {
           continue;
         }

pkg/analysis_server/test/analysis_abstract.dart

@@ -64,6 +64,9 @@ class AbstractAnalysisTest {
 
   AbstractAnalysisTest();
 
+  AnalysisDomainHandler get analysisHandler => server.handlers
+      .singleWhere((handler) => handler is AnalysisDomainHandler);
+
   void addAnalysisSubscription(AnalysisService service, String file) {
     // add file to subscription
     var files = analysisSubscriptions[service];
@@ -143,7 +146,7 @@ class AbstractAnalysisTest {
     resourceProvider.newFolder(projectPath);
     Request request =
         new AnalysisSetAnalysisRootsParams([projectPath], []).toRequest('0');
-    handleSuccessfulRequest(request);
+    handleSuccessfulRequest(request, handler: analysisHandler);
   }
 
   /**
@@ -171,7 +174,8 @@ class AbstractAnalysisTest {
   /**
    * Validates that the given [request] is handled successfully.
    */
-  Response handleSuccessfulRequest(Request request) {
+  Response handleSuccessfulRequest(Request request, {RequestHandler handler}) {
+    handler ??= this.handler;
     Response response = handler.handleRequest(request);
     expect(response, isResponseSuccess(request.id));
     return response;
@@ -203,8 +207,7 @@ class AbstractAnalysisTest {
     packageMapProvider = new MockPackageMapProvider();
     Index index = createIndex();
     server = createAnalysisServer(index);
-    handler = server.handlers
-        .singleWhere((handler) => handler is AnalysisDomainHandler);
+    handler = analysisHandler;
     // listen for notifications
     Stream<Notification> notificationStream =
         serverChannel.notificationController.stream;

pkg/analysis_server/test/edit/fixes_test.dart

@@ -27,13 +27,13 @@ class FixesTest extends AbstractAnalysisTest {
   @override
   void setUp() {
     super.setUp();
-    createProject();
     ExtensionManager manager = new ExtensionManager();
     manager.processPlugins([server.serverPlugin]);
     handler = new EditDomainHandler(server);
   }
 
   test_fixUndefinedClass() async {
+    createProject();
     addTestFile('''
 main() {
   Future<String> x = null;
@@ -52,6 +52,7 @@ main() {
   }
 
   test_hasFixes() async {
+    createProject();
     addTestFile('''
 foo() {
   print(1)
@@ -77,19 +78,13 @@ bar() {
   }
 
   test_overlayOnlyFile() async {
-    // add an overlay-only file
-    {
-      testCode = '''
+    createProject();
+    testCode = '''
 main() {
-  print(1)
+print(1)
 }
 ''';
-      Request request = new AnalysisUpdateContentParams(
-          {testFile: new AddContentOverlay(testCode)}).toRequest('0');
-      Response response =
-          new AnalysisDomainHandler(server).handleRequest(request);
-      expect(response, isResponseSuccess('0'));
-    }
+    _addOverlay(testFile, testCode);
     // ask for fixes
     await waitForTasksFinished();
     List<AnalysisErrorFixes> errorFixes = await _getFixesAt('print(1)');
@@ -97,6 +92,40 @@ main() {
     _isSyntacticErrorWithSingleFix(errorFixes[0]);
   }
 
+  test_suggestImportFromDifferentAnalysisRoot() async {
+    // Set up two projects.
+    resourceProvider..newFolder("/project1")..newFolder("/project2");
+    handleSuccessfulRequest(
+        new AnalysisSetAnalysisRootsParams(["/project1", "/project2"], [])
+            .toRequest('0'),
+        handler: analysisHandler);
+
+    // Set up files.
+    testFile = "/project1/main.dart";
+    testCode = "main() { print(new Foo()); }";
+    _addOverlay(testFile, testCode);
+    // Add another file in the same project that imports the target file.
+    // This ensures it will be analyzed as an implicit Source.
+    _addOverlay("/project1/another.dart", 'import "../project2/target.dart";');
+    _addOverlay("/project2/target.dart", "class Foo() {}");
+
+    await waitForTasksFinished();
+
+    List<String> fixes = (await _getFixesAt('Foo()'))
+        .single
+        .fixes
+        .map((f) => f.message)
+        .toList();
+    expect(fixes, contains("Import library '../project2/target.dart'"));
+  }
+
+  void _addOverlay(String name, String contents) {
+    Request request =
+        new AnalysisUpdateContentParams({name: new AddContentOverlay(contents)})
+            .toRequest('0');
+    handleSuccessfulRequest(request, handler: analysisHandler);
+  }
+
   Future<List<AnalysisErrorFixes>> _getFixes(int offset) async {
     Request request = new EditGetFixesParams(testFile, offset).toRequest('0');
     Response response = await waitResponse(request);

pkg/analysis_server/test/search/abstract_search_domain.dart

@@ -94,8 +94,8 @@ class AbstractSearchDomainTest extends AbstractAnalysisTest {
   @override
   void setUp() {
     super.setUp();
-    server.handlers = [new SearchDomainHandler(server),];
     createProject();
+    server.handlers = [new SearchDomainHandler(server),];
   }
 
   Future waitForSearchResults() {

pkg/analysis_server/test/search/type_hierarchy_test.dart

@@ -33,8 +33,8 @@ class GetTypeHierarchyTest extends AbstractAnalysisTest {
   @override
   void setUp() {
     super.setUp();
-    server.handlers = [new SearchDomainHandler(server),];
     createProject();
+    server.handlers = [new SearchDomainHandler(server),];
   }
 
   test_bad_function() async {