Reapply "Tweak public APIs and use them in patch_sdk, dart2js, and kernel-service.""

pkg/front_end/test/fasta/shaker_test.dart

 // Copyright (c) 2017, 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.md file.
 
 /// Tests basic functionality of the API tree-shaker.
 ///
 /// Each input file is built and tree-shaken, then we check that the set of
 /// libraries, classes, and members that are retained match those declared in an
 /// expectations file.
 ///
 /// Input files may contain markers to turn on flags that configure this
 /// runner. Currently only the following marker is recognized:
 ///   @@SHOW_CORE_LIBRARIES@@ - whether to check for retained information from
 ///      the core libraries. By default this runner only checks for members of
 ///      pkg/front_end/testcases/shaker/lib/lib.dart.
 library fasta.test.shaker_test;
 
 import 'dart:async' show Future;
 import 'dart:convert' show JSON;
 import 'dart:io' show File;
 
 export 'package:testing/testing.dart' show Chain, runMe;
 import 'package:front_end/physical_file_system.dart';
 import 'package:front_end/src/fasta/dill/dill_target.dart' show DillTarget;
 import 'package:front_end/src/fasta/errors.dart' show InputError;
+import 'package:front_end/src/fasta/kernel/kernel_outline_shaker.dart';
 import 'package:front_end/src/fasta/kernel/kernel_target.dart'
     show KernelTarget;
 import 'package:front_end/src/fasta/kernel/verifier.dart' show verifyProgram;
 import 'package:front_end/src/fasta/testing/kernel_chain.dart' show runDiff;
 import 'package:front_end/src/fasta/testing/patched_sdk_location.dart';
 import 'package:front_end/src/fasta/ticker.dart' show Ticker;
 import 'package:front_end/src/fasta/translate_uri.dart' show TranslateUri;
 import 'package:front_end/src/fasta/util/relativize.dart' show relativizeUri;
 import 'package:kernel/ast.dart' show Program;
 import 'package:kernel/kernel.dart' show loadProgramFromBytes;
@@ skipping 22 matching lines @@
       new ExpectationSet.fromJsonList(JSON.decode(EXPECTATIONS));
 
   TreeShakerContext(this.outlineUri, this.uriTranslator, this.outlineBytes,
       bool updateExpectations)
       : steps = <Step>[
           const BuildProgram(),
           new CheckShaker(updateExpectations: updateExpectations),
         ];
 
   Program loadPlatformOutline() {
-    // Note: we rebuild the platform outline on every test because the compiler
-    // currently mutates the in-memory representation of the program without
+    // Note: we rebuild the platform outline on every test because the
+    // tree-shaker mutates the in-memory representation of the program without
     // cloning it.
     return loadProgramFromBytes(outlineBytes);
   }
 
   static create(Map<String, String> environment) async {
     environment[ENABLE_FULL_COMPILE] = "";
     environment[AST_KIND_INDEX] = "${AstKind.Kernel.index}";
     bool updateExpectations = environment["updateExpectations"] == "true";
     Uri sdk = await computePatchedSdk();
     Uri outlineUri = sdk.resolve('outline.dill');
@@ skipping 20 matching lines @@
       var dillTarget = new DillTarget(
           new Ticker(isVerbose: false),
           context.uriTranslator,
           new VmFastaTarget(new TargetFlags(strongMode: false)));
       dillTarget.loader.appendLibraries(platformOutline);
       var sourceTarget = new KernelTarget(
           PhysicalFileSystem.instance, dillTarget, context.uriTranslator);
       await dillTarget.buildOutlines();
 
       var inputUri = description.uri;
-
-      /// We treat the lib.dart library as a special dependency that was
-      /// previously built. To do so, we build it and append it back to the
-      /// dillTarget before building the actual test.
       var libUri = inputUri.resolve('lib/lib.dart');
       sourceTarget.read(libUri);
-      dillTarget.loader.appendLibraries(
-          await sourceTarget.buildOutlines(), (uri) => uri == libUri);
-
-      /// This new KernelTarget contains only sources from the test without
-      /// lib.dart.
-      sourceTarget = new KernelTarget(
-          PhysicalFileSystem.instance, dillTarget, context.uriTranslator);
-
-      await dillTarget.buildOutlines();
       sourceTarget.read(inputUri);
       var contents = new File.fromUri(inputUri).readAsStringSync();
       var showCoreLibraries = contents.contains("@@SHOW_CORE_LIBRARIES@@");
-
       await sourceTarget.buildOutlines();
-      // Note: We run the tree-shaker as a separate step on this suite to be
-      // able to specify what libraries to tree shake (by default only the code
-      // in the dillTarget gets tree-shaken). We could apply the tree-shaker
-      // twice, but that seems unnecessary.
-      var program = await sourceTarget.buildProgram(trimDependencies: true);
+      var program = await sourceTarget.buildProgram();
+      bool isIncluded(Uri uri) => !_isTreeShaken(uri);
+      trimProgram(program, isIncluded);
       return pass(new _IntermediateData(inputUri, program, showCoreLibraries));
     } on InputError catch (e, s) {
       return fail(null, e.error, s);
     }
   }
 }
 
 /// Intermediate result from the testing chain.
 class _IntermediateData {
   /// The input URI provided to the test.
@@ skipping 11 matching lines @@
 }
 
 /// A step that runs the tree-shaker and checks againt an expectation file for
 /// the list of members and classes that should be preserved by the tree-shaker.
 class CheckShaker extends Step<_IntermediateData, String, ChainContext> {
   final bool updateExpectations;
   const CheckShaker({this.updateExpectations: false});
 
   String get name => "match shaker expectation";
 
-  /// Tree-shake dart:* libraries and the library under [_specialLibraryPath].
-  bool _isTreeShaken(Uri uri) =>
-      uri.isScheme('dart') ||
-      Uri.base.resolveUri(uri).path.endsWith(_specialLibraryPath);
-
   Future<Result<String>> run(
       _IntermediateData data, ChainContext context) async {
     String actualResult;
-    var entryUri = data.program.libraries
-        .firstWhere((l) => !l.importUri.isScheme('dart'))
-        .importUri;
-
+    var entryUri = data.uri;
     var program = data.program;
 
     var errors = verifyProgram(program, isOutline: false);
     if (!errors.isEmpty) {
       return new Result<String>(
           null, context.expectationSet["VerificationError"], errors, null);
     }
 
     // Build a text representation of what we expect to be retained.
     var buffer = new StringBuffer();
@@ skipping 49 matching lines @@
           """
 Please create file ${expectedFile.path} with this content:
 $buffer""");
     }
   }
 }
 
 /// A special library used only to test the shaker. The suite above will
 /// tree-shake the contents of this library.
 const _specialLibraryPath = 'pkg/front_end/testcases/shaker/lib/lib.dart';
+
+/// Tree-shake dart:* libraries and the library under [_specialLibraryPath].
+bool _isTreeShaken(Uri uri) =>
+    uri.isScheme('dart') ||
+    Uri.base.resolveUri(uri).path.endsWith(_specialLibraryPath);