Fix summary handling of unresolved imports, exports, and parts.

pkg/analyzer/test/src/summary/resynthesize_ast_test.dart

 // Copyright (c) 2016, 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 analyzer.test.src.summary.resynthesize_ast_test;
 
 import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/src/dart/element/element.dart';
 import 'package:analyzer/src/generated/engine.dart'
     show AnalysisContext, AnalysisOptionsImpl;
 import 'package:analyzer/src/generated/sdk.dart';
 import 'package:analyzer/src/generated/source.dart';
 import 'package:analyzer/src/summary/format.dart';
 import 'package:analyzer/src/summary/idl.dart';
 import 'package:analyzer/src/summary/link.dart';
 import 'package:analyzer/src/summary/prelink.dart';
 import 'package:analyzer/src/summary/resynthesize.dart';
 import 'package:analyzer/src/summary/summarize_ast.dart';
 import 'package:analyzer/src/summary/summarize_elements.dart'
     show PackageBundleAssembler;
 import 'package:analyzer/task/dart.dart' show PARSED_UNIT;
+import 'package:analyzer/task/general.dart';
 import 'package:unittest/unittest.dart';
 
 import '../../reflective_tests.dart';
 import '../context/abstract_context.dart';
 import '../task/strong/inferred_type_test.dart';
 import 'resynthesize_test.dart';
 import 'summary_common.dart';
 
 main() {
   groupSep = ' | ';
@@ skipping 674 matching lines @@
 
   @override
   TestSummaryResynthesizer encodeDecodeLibrarySource(Source source) {
     return _encodeLibrary(source);
   }
 }
 
 /**
  * Abstract mixin for serializing ASTs and resynthesizing elements from it.
  */
-abstract class _AstResynthesizeTestMixin {
+abstract class _AstResynthesizeTestMixin
+    implements _AstResynthesizeTestMixinInterface {
   final Set<Source> serializedSources = new Set<Source>();
   final PackageBundleAssembler bundleAssembler = new PackageBundleAssembler();
   final Map<String, UnlinkedUnitBuilder> uriToUnit =
       <String, UnlinkedUnitBuilder>{};
 
   AnalysisContext get context;
 
   LibraryElementImpl _encodeDecodeLibraryElement(Source source) {
     SummaryResynthesizer resynthesizer = _encodeLibrary(source);
     return resynthesizer.getLibraryElement(source.uri.toString());
   }
 
   TestSummaryResynthesizer _encodeLibrary(Source source) {
     _serializeLibrary(source);
 
     PackageBundle bundle =
         new PackageBundle.fromBuffer(bundleAssembler.assemble().toBuffer());
 
     Map<String, UnlinkedUnit> unlinkedSummaries = <String, UnlinkedUnit>{};
     for (int i = 0; i < bundle.unlinkedUnitUris.length; i++) {
       String uri = bundle.unlinkedUnitUris[i];
       unlinkedSummaries[uri] = bundle.unlinkedUnits[i];
     }
 
     LinkedLibrary getDependency(String absoluteUri) {
       Map<String, LinkedLibrary> sdkLibraries =
           SerializedMockSdk.instance.uriToLinkedLibrary;
       LinkedLibrary linkedLibrary = sdkLibraries[absoluteUri];
-      if (linkedLibrary == null) {
+      if (linkedLibrary == null && !allowMissingFiles) {
         fail('Linker unexpectedly requested LinkedLibrary for "$absoluteUri".'
             '  Libraries available: ${sdkLibraries.keys}');
       }
       return linkedLibrary;
     }
 
     UnlinkedUnit getUnit(String absoluteUri) {
       UnlinkedUnit unit = uriToUnit[absoluteUri] ??
           SerializedMockSdk.instance.uriToUnlinkedUnit[absoluteUri];
-      if (unit == null) {
+      if (unit == null && !allowMissingFiles) {
         fail('Linker unexpectedly requested unit for "$absoluteUri".');
       }
       return unit;
     }
 
     Set<String> nonSdkLibraryUris = context.sources
         .where((Source source) =>
             !source.isInSystemLibrary &&
             context.computeKindOf(source) == SourceKind.LIBRARY)
         .map((Source source) => source.uri.toString())
         .toSet();
 
     Map<String, LinkedLibrary> linkedSummaries = link(nonSdkLibraryUris,
         getDependency, getUnit, context.analysisOptions.strongMode);
 
     return new TestSummaryResynthesizer(
         null,
         context,
         new Map<String, UnlinkedUnit>()
           ..addAll(SerializedMockSdk.instance.uriToUnlinkedUnit)
           ..addAll(unlinkedSummaries),
         new Map<String, LinkedLibrary>()
           ..addAll(SerializedMockSdk.instance.uriToLinkedLibrary)
-          ..addAll(linkedSummaries));
+          ..addAll(linkedSummaries),
+        allowMissingFiles);
   }
 
   UnlinkedUnit _getUnlinkedUnit(Source source) {
     String uriStr = source.uri.toString();
     {
       UnlinkedUnit unlinkedUnitInSdk =
           SerializedMockSdk.instance.uriToUnlinkedUnit[uriStr];
       if (unlinkedUnitInSdk != null) {
         return unlinkedUnitInSdk;
       }
     }
     return uriToUnit.putIfAbsent(uriStr, () {
+      int modificationTime = context.computeResult(source, MODIFICATION_TIME);
+      if (modificationTime < 0) {
+        // Source does not exist.
+        if (!allowMissingFiles) {
+          fail('Unexpectedly tried to get unlinked summary for $source');
+        }
+        return null;
+      }
       CompilationUnit unit = context.computeResult(source, PARSED_UNIT);
       UnlinkedUnitBuilder unlinkedUnit = serializeAstUnlinked(unit);
       bundleAssembler.addUnlinkedUnit(source, unlinkedUnit);
       return unlinkedUnit;
     });
   }
 
   void _serializeLibrary(Source librarySource) {
     if (librarySource.isInSystemLibrary) {
       return;
@@ skipping 10 matching lines @@
             '$librarySource (${librarySource.runtimeType})');
       }
       return resolvedSource;
     }
 
     UnlinkedUnit getPart(String relativeUri) {
       return _getUnlinkedUnit(resolveRelativeUri(relativeUri));
     }
 
     UnlinkedPublicNamespace getImport(String relativeUri) {
-      return getPart(relativeUri).publicNamespace;
+      return getPart(relativeUri)?.publicNamespace;
     }
 
     UnlinkedUnit definingUnit = _getUnlinkedUnit(librarySource);
-    LinkedLibraryBuilder linkedLibrary =
-        prelink(definingUnit, getPart, getImport);
-    linkedLibrary.dependencies.skip(1).forEach((LinkedDependency d) {
-      _serializeLibrary(resolveRelativeUri(d.uri));
-    });
+    if (definingUnit != null) {
+      LinkedLibraryBuilder linkedLibrary =
+          prelink(definingUnit, getPart, getImport);
+      linkedLibrary.dependencies.skip(1).forEach((LinkedDependency d) {
+        _serializeLibrary(resolveRelativeUri(d.uri));
+      });
+    }
   }
 }
+
+/**
+ * Interface that [_AstResynthesizeTestMixin] requires of classes it's mixed
+ * into.  We can't place the getter below into [_AstResynthesizeTestMixin]
+ * directly, because then it would be overriding a field at the site where the
+ * mixin is instantiated.
+ */
+abstract class _AstResynthesizeTestMixinInterface {
+  /**
+   * A test should return `true` to indicate that a missing file at the time of
+   * summary resynthesis shouldn't trigger an error.
+   */
+  bool get allowMissingFiles;
+}