Refactor summary tests in preparation for adding a one-phase summary API.

I will soon be adding an API for generating summaries that generates
them in one phase, as opposed to the current two-phase approach of
building unlinked summaries and then linking them together.  This is
will be needed in order to support full type inference of summaries,
since full type inference requires examining the contents of
block-bodied closures, and it's not worth the effort of trying
serialize the contents of block-bodied closures into unlinked
summaries.

To prepare for this, the summary tests need to be generalized so that
during the transition period they will be able to be run with either
API.

This CL introduces several classes in a new `test_strategies.dart` file:

- Interfaces `SummaryBaseTestStrategy`, `SummaryBlackBoxTestStrategy`,
  and `SummaryLinkerTestStrategy`.  These interfaces define the
  methods that can be invoked by tests of the summary mechanism.

- Implementations of those interfaces:
  `SummaryBlackBoxTestStrategyPrelink`,
  `SummaryBlackBoxTestStrategyTwoPhase`, and
  `SummaryLinkerTestStrategyTwoPhase`.  These classes provide the
  ability to drive the summary mechanism in various ways.  When the
  one-phase API is added, more classes will be added to drive it.

- A few private classes occupying intermediate positions in the class
  hierarchy, as well as auxiliary data structures needed by the above
  classes.

The tests themselves have been moved into mixin classes so that they
can be applied to any of the implementations above.

Change-Id: Iac3585944297f78f184d35de544aa4c8d8abe99a
Reviewed-on: https://dart-review.googlesource.com/72320
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>

Author: stereotype441

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

@@ -4,13 +4,12 @@
 
 import 'package:analyzer/dart/element/type.dart';
 import 'package:analyzer/src/dart/element/element.dart';
-import 'package:analyzer/src/summary/format.dart';
 import 'package:analyzer/src/summary/idl.dart';
 import 'package:analyzer/src/summary/link.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
-import 'summarize_ast_test.dart';
+import 'test_strategies.dart';
 
 main() {
   defineReflectiveSuite(() {
@@ -19,29 +18,17 @@ main() {
 }
 
 @reflectiveTest
-class LinkerUnitTest extends SummaryLinkerTest {
-  Linker linker;
-
-  LinkerInputs linkerInputs;
-  LibraryElementInBuildUnit _testLibrary;
-  @override
-  bool get allowMissingFiles => false;
-
+class LinkerUnitTest extends SummaryLinkerTestStrategyTwoPhase
+    with LinkerUnitTestCases {}
+
+/// Test cases that exercise the summary linker in a white-box fashion.
+///
+/// These test cases may be mixed into any class derived from
+/// [SummaryLinkerTestStrategy], allowing the linker to be unit-tested in a
+/// variety of ways.
+abstract class LinkerUnitTestCases implements SummaryLinkerTestStrategy {
   Matcher get isUndefined => const TypeMatcher<UndefinedElementForLink>();
 
-  LibraryElementInBuildUnit get testLibrary => _testLibrary ??=
-      linker.getLibrary(linkerInputs.testDartUri) as LibraryElementInBuildUnit;
-
-  void createLinker(String text, {String path: '/test.dart'}) {
-    linkerInputs = createLinkerInputs(text, path: path);
-    Map<String, LinkedLibraryBuilder> linkedLibraries = setupForLink(
-        linkerInputs.linkedLibraries,
-        linkerInputs.getUnit,
-        linkerInputs.getDeclaredVariable);
-    linker = new Linker(
-        linkedLibraries, linkerInputs.getDependency, linkerInputs.getUnit);
-  }
-
   LibraryElementForLink getLibrary(String uri) {
     return linker.getLibrary(Uri.parse(uri));
   }

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

@@ -2,47 +2,22 @@
 // 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.
 
-import 'package:analyzer/src/summary/idl.dart';
-import 'package:analyzer/src/summary/prelink.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
-import 'summarize_ast_test.dart';
 import 'summary_common.dart';
+import 'test_strategies.dart';
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(PrelinkerTest);
   });
 }
 
-/**
- * Override of [SummaryTest] which verifies the correctness of the prelinker by
- * creating summaries from the element model, discarding their prelinked
- * information, and then recreating it using the prelinker.
- */
+/// Tests for the pre-linker which exercise it using the old (two-phase) summary
+/// generation strategy.
+///
+/// TODO(paulberry): eliminate these tests once we have transitioned over to
+/// one-step summary generation.
 @reflectiveTest
-class PrelinkerTest extends LinkedSummarizeAstTest {
-  @override
-  bool get skipFullyLinkedData => true;
-
-  @override
-  void serializeLibraryText(String text, {bool allowErrors: false}) {
-    super.serializeLibraryText(text, allowErrors: allowErrors);
-
-    UnlinkedUnit getPart(String absoluteUri) {
-      return linkerInputs.getUnit(absoluteUri);
-    }
-
-    UnlinkedPublicNamespace getImport(String absoluteUri) {
-      return getPart(absoluteUri)?.publicNamespace;
-    }
-
-    linked = new LinkedLibrary.fromBuffer(prelink(
-        linkerInputs.testDartUri.toString(),
-        linkerInputs.unlinkedDefiningUnit,
-        getPart,
-        getImport,
-        (String declaredVariable) => null).toBuffer());
-    validateLinkedLibrary(linked);
-  }
-}
+class PrelinkerTest extends SummaryBlackBoxTestStrategyPrelink
+    with SummaryTestCases {}

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

@@ -28,7 +28,7 @@ import 'package:test_reflective_loader/test_reflective_loader.dart';
 import '../context/abstract_context.dart';
 import 'element_text.dart';
 import 'resynthesize_common.dart';
-import 'summary_common.dart';
+import 'test_strategies.dart';
 
 main() {
   defineReflectiveSuite(() {

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

@@ -4,19 +4,18 @@
 
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
-import 'summarize_ast_test.dart';
+import 'summary_common.dart';
+import 'test_strategies.dart';
 
 main() {
   defineReflectiveSuite(() {
     defineReflectiveTests(LinkedSummarizeAstStrongTest);
   });
 }
 
-/**
- * Override of [LinkedSummarizeAstTest] which uses strong mode.
- */
 @reflectiveTest
-class LinkedSummarizeAstStrongTest extends LinkedSummarizeAstTest {
+class LinkedSummarizeAstStrongTest extends SummaryBlackBoxTestStrategyTwoPhase
+    with SummaryTestCases {
   @override
   @failingTest
   test_bottom_reference_shared() {