Migration: programmatically generate package_config.json in unit tests.

Previously, we hard a hard-coded set that included all packages added
by unit tests, which created confusion when writing new unit tests.
Now, `addPackageFile` records a list of all packages and
`package_config.json` is automatically generated just before analysis
begins.

Change-Id: I3393c0266a54d051ffa7601e74753a75857635e2
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/170024
Reviewed-by: Samuel Rawlins <srawlins@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>

Author: stereotype441

pkg/nnbd_migration/test/abstract_context.dart

@@ -2,6 +2,8 @@
 // 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 'dart:convert';
+
 import 'package:analyzer/dart/analysis/analysis_context.dart';
 import 'package:analyzer/dart/analysis/analysis_context_collection.dart';
 import 'package:analyzer/dart/analysis/session.dart';
@@ -23,7 +25,19 @@ class AbstractContextTest with ResourceProviderMixin {
   AnalysisContextCollection _analysisContextCollection;
   AnalysisDriver _driver;
 
-  AnalysisDriver get driver => _driver;
+  final Set<String> knownPackages = {};
+
+  /// Whether the test should perform analysis with NNBD enabled.
+  ///
+  /// `false` by default.  May be overridden in derived test classes.
+  bool get analyzeWithNnbd => false;
+
+  AnalysisDriver get driver {
+    if (_driver == null) {
+      _createAnalysisContexts();
+    }
+    return _driver;
+  }
 
   String get homePath => '/home';
 
@@ -49,7 +63,7 @@ class Required {
   /// package.
   File addPackageFile(String packageName, String pathInLib, String content) {
     var packagePath = '/.pub-cache/$packageName';
-    _addTestPackageDependency(packageName, packagePath);
+    knownPackages.add(packageName);
     return newFile('$packagePath/lib/$pathInLib', content: content);
   }
 
@@ -91,22 +105,13 @@ export 'package:test_core/test_core.dart';
 ''');
   }
 
-  /// Create all analysis contexts in [_homePath].
-  void createAnalysisContexts() {
-    _analysisContextCollection = AnalysisContextCollectionImpl(
-      includedPaths: [convertPath(homePath)],
-      enableIndex: true,
-      resourceProvider: overlayResourceProvider,
-      sdkPath: convertPath('/sdk'),
-    );
-
-    _driver = getDriver(convertPath(testsPath));
-  }
-
   /// Return the existing analysis context that should be used to analyze the
   /// given [path], or throw [StateError] if the [path] is not analyzed in any
   /// of the created analysis contexts.
   AnalysisContext getContext(String path) {
+    if (_analysisContextCollection == null) {
+      _createAnalysisContexts();
+    }
     path = convertPath(path);
     return _analysisContextCollection.contextFor(path);
   }
@@ -142,86 +147,6 @@ environment:
   sdk: '>=2.9.0 <3.0.0'
 ''');
     }
-    var packageConfigPath = '$testsPath/.dart_tool/package_config.json';
-    // Subclasses may write out a different file first.
-    if (!getFile(packageConfigPath).exists) {
-      // TODO(srawlins): This is a rough hack to allow for the "null safe by
-      // default" flag flip. We need to _opt out_ all packages at the onset.
-      // A better solution likely involves the package config-editing code in
-      // analyzer's [context_collection_resolution.dart].
-      newFile(packageConfigPath, content: '''
-{
-  "configVersion": 2,
-  "packages": [
-    {
-      "name": "args",
-      "rootUri": "${toUriStr('/.pub-cache/args')}",
-      "packageUri": "lib/",
-      "languageVersion": "2.9"
-    },
-    {
-      "name": "collection",
-      "rootUri": "${toUriStr('/.pub-cache/collection')}",
-      "packageUri": "lib/",
-      "languageVersion": "2.9"
-    },
-    {
-      "name": "fixnum",
-      "rootUri": "${toUriStr('/.pub-cache/fixnum')}",
-      "packageUri": "lib/",
-      "languageVersion": "2.9"
-    },
-    {
-      "name": "foo",
-      "rootUri": "${toUriStr('/.pub-cache/foo')}",
-      "packageUri": "lib/",
-      "languageVersion": "2.9"
-    },
-    {
-      "name": "http",
-      "rootUri": "${toUriStr('/.pub-cache/http')}",
-      "packageUri": "lib/",
-      "languageVersion": "2.9"
-    },
-    {
-      "name": "meta",
-      "rootUri": "${toUriStr('/.pub-cache/meta')}",
-      "packageUri": "lib/",
-      "languageVersion": "2.9"
-    },
-    {
-      "name": "quiver",
-      "rootUri": "${toUriStr('/.pub-cache/quiver')}",
-      "packageUri": "lib/",
-      "languageVersion": "2.9"
-    },
-    {
-      "name": "test",
-      "rootUri": "${toUriStr('/.pub-cache/test')}",
-      "packageUri": "lib/",
-      "languageVersion": "2.9"
-    },
-    {
-      "name": "test_core",
-      "rootUri": "${toUriStr('/.pub-cache/test_core')}",
-      "packageUri": "lib/",
-      "languageVersion": "2.9"
-    },
-    {
-      "name": "tests",
-      "rootUri": "../",
-      "packageUri": "lib/",
-      "languageVersion": "2.9"
-    }
-  ],
-  "generated": "2020-10-21T21:13:05.186004Z",
-  "generator": "pub",
-  "generatorVersion": "2.10.0"
-}
-''');
-    }
-
-    createAnalysisContexts();
   }
 
   void setupResourceProvider() {}
@@ -230,33 +155,38 @@ environment:
     AnalysisEngine.instance.clearCaches();
   }
 
-  void _addTestPackageDependency(String name, String rootPath) {
-    var packagesFile = getFile('$testsPath/.packages');
-    var packagesContent = packagesFile.readAsStringSync();
-
-    // Ignore if there is already the same package dependency.
-    if (packagesContent.contains('$name:file://')) {
-      return;
-    }
-
-    packagesContent += '$name:${toUri('$rootPath/lib')}\n';
-
-    packagesFile.writeAsStringSync(packagesContent);
-
-    _createDriver();
-  }
-
-  void _createDriver() {
-    var collection = AnalysisContextCollectionImpl(
+  /// Create all analysis contexts in [_homePath].
+  void _createAnalysisContexts() {
+    var packageConfigJson = {
+      'configVersion': 2,
+      'packages': [
+        for (var packageName in knownPackages)
+          {
+            'name': packageName,
+            'rootUri': toUriStr('/.pub-cache/$packageName'),
+            'packageUri': 'lib/',
+            'languageVersion': '2.9'
+          },
+        {
+          'name': 'tests',
+          'rootUri': '../',
+          'packageUri': 'lib/',
+          'languageVersion': analyzeWithNnbd ? '2.12' : '2.9'
+        }
+      ],
+      'generated': '2020-10-21T21:13:05.186004Z',
+      'generator': 'pub',
+      'generatorVersion': '2.10.0'
+    };
+    newFile('$testsPath/.dart_tool/package_config.json',
+        content: JsonEncoder.withIndent('  ').convert(packageConfigJson));
+    _analysisContextCollection = AnalysisContextCollectionImpl(
       includedPaths: [convertPath(homePath)],
       enableIndex: true,
-      resourceProvider: resourceProvider,
+      resourceProvider: overlayResourceProvider,
       sdkPath: convertPath('/sdk'),
     );
 
-    var testPath = convertPath(testsPath);
-    var context = collection.contextFor(testPath) as DriverBasedAnalysisContext;
-
-    _driver = context.driver;
+    _driver = getDriver(convertPath(testsPath));
   }
 }

pkg/nnbd_migration/test/abstract_single_unit.dart

@@ -30,13 +30,6 @@ class AbstractSingleUnitTest extends AbstractContextTest {
   FindNode findNode;
   FindElement findElement;
 
-  /// Whether the test should perform analysis with NNBD enabled.
-  ///
-  /// `false` by default.  May be overridden in derived test classes.
-  ///
-  /// TODO(paulberry): once NNBD ships, this should no longer be needed.
-  bool get analyzeWithNnbd => false;
-
   void addTestSource(String code, [Uri uri]) {
     testCode = code;
     testSource = addSource(testFile, code, uri);
@@ -80,28 +73,6 @@ name: tests
 version: 1.0.0
 environment:
   sdk: '>=2.12.0 <3.0.0'
-''');
-      newFile('$testRoot/.dart_tool/package_config.json', content: '''
-{
-  "configVersion": 2,
-  "packages": [
-    {
-      "name": "meta",
-      "rootUri": "file:///.pub-cache/meta",
-      "packageUri": "lib/",
-      "languageVersion": "2.12"
-    },
-    {
-      "name": "tests",
-      "rootUri": "../",
-      "packageUri": "lib/",
-      "languageVersion": "2.12"
-    }
-  ],
-  "generated": "2020-10-21T21:13:05.186004Z",
-  "generator": "pub",
-  "generatorVersion": "2.12.0"
-}
 ''');
     }
     super.setUp();