Automatically add plugin projects to Windows .sln (#51246)

Adds utility code for managing list of plugin projects within a solution file, updating them as the plugins change.

This is a prototype of an approach to solution-level portion of Windows plugin tooling; it may not be what the final plugin handling on Windows uses, but it makes things much better in the short term, and gives us a baseline to evaluate other possible solution management systems against.

Part of #32719

packages/flutter_tools/lib/src/plugins.dart

@@ -20,6 +20,7 @@ import 'macos/cocoapods.dart';
 import 'platform_plugins.dart';
 import 'project.dart';
 import 'windows/property_sheet.dart';
+import 'windows/visual_studio_solution_utils.dart';
 
 void _renderTemplateToFile(String template, dynamic context, String filePath) {
   final String renderedTemplate =
@@ -1038,6 +1039,7 @@ Future<void> injectPlugins(FlutterProject project, {bool checkProjects = false})
   }
   if (featureFlags.isWindowsEnabled && project.windows.existsSync()) {
     await _writeWindowsPluginFiles(project, plugins);
+    await VisualStudioSolutionUtils(project: project.windows, fileSystem: globals.fs).updatePlugins(plugins);
   }
   for (final XcodeBasedProject subproject in <XcodeBasedProject>[project.ios, project.macos]) {
     if (!project.isModule && (!checkProjects || subproject.existsSync())) {

packages/flutter_tools/lib/src/windows/visual_studio_project.dart

+// Copyright 2014 The Flutter Authors. 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:meta/meta.dart';
+import 'package:xml/xml.dart' as xml;
+
+import '../base/file_system.dart';
+
+/// A utility class for interacting with Visual Studio project files (e.g.,
+/// .vcxproj).
+class VisualStudioProject {
+  /// Creates a project object from the project file at [file].
+  VisualStudioProject(this.file, {
+    @required FileSystem fileSystem,
+  }): _fileSystem = fileSystem {
+    try {
+      content = xml.parse(file.readAsStringSync());
+    } on xml.XmlParserException {
+      // Silently continue; formatUnderstood will return false.
+    }
+  }
+
+  final FileSystem _fileSystem;
+
+  /// The file corresponding to this object.
+  final File file;
+
+  /// The content of the project file.
+  xml.XmlDocument content;
+
+  /// Whether or not the the project file was correctly parsed.
+  ///
+  /// If false, this could indicate that the project file is damaged, or that
+  /// it's an unsupported project type.
+  bool get formatUnderstood => content != null;
+
+  String _guid;
+
+  /// Returns the ProjectGuid for the project, or null if it's not present.
+  String get guid {
+    return _guid ??= _findGuid();
+  }
+
+  String _findGuid() {
+    if (!formatUnderstood) {
+      return null;
+    }
+    try {
+      final String guidValue = content.findAllElements('ProjectGuid').single.text.trim();
+      // Remove the enclosing {} from the value.
+      return guidValue.substring(1, guidValue.length - 1);
+    } on StateError {
+      // If there is not exactly one ProjectGuid, return null.
+      return null;
+    }
+  }
+
+  String _name;
+
+  /// Returns the ProjectName for the project.
+  ///
+  /// If not explicitly set in the project, uses the basename of the project
+  /// file.
+  String get name {
+    return _name ??= _findName();
+  }
+
+  String _findName() {
+    if (!formatUnderstood) {
+      return null;
+    }
+    try {
+      return content.findAllElements('ProjectName').first.text.trim();
+    } on StateError {
+      // If there is no name, fall back to filename.
+      return _fileSystem.path.basenameWithoutExtension(file.path);
+    }
+  }
+}

packages/flutter_tools/lib/src/windows/visual_studio_solution_utils.dart

+// Copyright 2014 The Flutter Authors. 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:meta/meta.dart';
+
+import '../base/common.dart';
+import '../base/file_system.dart';
+import '../convert.dart';
+import '../plugins.dart';
+import '../project.dart';
+import 'visual_studio_project.dart';
+
+// Constants corresponding to specific reference types in a solution file.
+// These values are defined by the .sln format.
+const String _kSolutionTypeGuidFolder = '2150E333-8FDC-42A3-9474-1A3956D46DE8';
+const String _kSolutionTypeGuidVcxproj = '8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942';
+
+// The GUID for the folder above, managed by this class. This is an arbitrary
+// value that was randomly generated, but it should not be changed since that
+// would cause issues for existing Flutter projects.
+const String _kFlutterPluginSolutionFolderGuid = '5C2E738A-1DD3-445A-AAC8-EEB9648DD07C';
+// The FlutterBuild project GUID. This is an arbitrary
+// value that was randomly generated, but it should not be changed since that
+// would cause issues for existing Flutter projects.
+const String _kFlutterBuildProjectGuid = '6419BF13-6ECD-4CD2-9E85-E566A1F03F8F';
+
+/// Extracts and stores the plugin name and vcxproj GUID for [plugin].
+class _PluginProjectInfo {
+  _PluginProjectInfo(Plugin plugin, {
+    @required FileSystem fileSystem,
+  }) {
+    name = plugin.name;
+    final File projectFile = fileSystem.directory(plugin.path).childDirectory('windows').childFile('plugin.vcxproj');
+    guid = VisualStudioProject(projectFile, fileSystem: fileSystem).guid;
+    if (guid == null) {
+      throwToolExit('Unable to find a plugin.vcxproj for plugin "$name"');
+    }
+  }
+
+  // The name of the plugin, which is also the name of the symlink folder.
+  String name;
+
+  // The GUID of the plugin's project.
+  String guid;
+}
+
+// TODO(stuartmorgan): Consider replacing this class with a real parser. See
+// https://github.com/flutter/flutter/issues/51430.
+
+class VisualStudioSolutionUtils {
+  const VisualStudioSolutionUtils({
+    @required WindowsProject project,
+    @required FileSystem fileSystem,
+  }) : _project = project,
+       _fileSystem = fileSystem;
+
+  final WindowsProject _project;
+  final FileSystem _fileSystem;
+
+  /// Updates the solution file for [project] to have the project references and
+  /// dependencies to include [plugins], removing any previous plugins from the
+  /// solution.
+  Future<void> updatePlugins(List<Plugin> plugins) async {
+    final String solutionContent = await _project.solutionFile.readAsString();
+
+    // Map of GUID to name for the current plugin list.
+    final Map<String, String> currentPluginInfo = _getWindowsPluginNamesByGuid(plugins);
+
+    // Find any plugins referenced in the project that are no longer used, and
+    // any that are new.
+    //
+    // While the simplest approach to updating the solution would be to remove all
+    // entries associated with plugins, and then add all the current plugins in
+    // one block, Visual Studio has its own (unknown, likely data-structure-hash
+    // based) order that it will use each time it writes out the file due to any
+    // solution-level changes made in the UI. To avoid thrashing, and resulting
+    // confusion (e.g., in review diffs), this update attempts to instead preserve
+    // the ordering that is already there, so that once Visual Studio has
+    // reordered the plugins, that order will be stable.
+    final Set<String> existingPlugins = _findPreviousPluginGuids(solutionContent);
+    final Set<String> currentPlugins = currentPluginInfo.keys.toSet();
+    final Set<String> removedPlugins = existingPlugins.difference(currentPlugins);
+    final Set<String> addedPlugins = currentPlugins.difference(existingPlugins);
+
+    final RegExp projectStartPattern = RegExp(r'^Project\("{' + _kSolutionTypeGuidVcxproj + r'}"\)\s*=\s*".*",\s*"(.*)",\s*"{([A-Fa-f0-9\-]*)}"\s*$');
+    final RegExp pluginsFolderProjectStartPattern = RegExp(r'^Project\("{' + _kSolutionTypeGuidFolder + r'}"\)\s*=.*"{' + _kFlutterPluginSolutionFolderGuid + r'}"\s*$');
+    final RegExp projectEndPattern = RegExp(r'^EndProject\s*$');
+    final RegExp globalStartPattern = RegExp(r'^Global\s*$');
+    final RegExp globalEndPattern = RegExp(r'^EndGlobal\s*$');
+    final RegExp projectDependenciesStartPattern = RegExp(r'^\s*ProjectSection\(ProjectDependencies\)\s*=\s*postProject\s*$');
+    final RegExp globalSectionProjectConfigurationStartPattern = RegExp(r'^\s*GlobalSection\(ProjectConfigurationPlatforms\)\s*=\s*postSolution\s*$');
+    final RegExp globalSectionNestedProjectsStartPattern = RegExp(r'^\s*GlobalSection\(NestedProjects\)\s*=\s*preSolution\s*$');
+
+    final StringBuffer newSolutionContent = StringBuffer();
+    // readAsString drops the BOM; re-add it.
+    newSolutionContent.writeCharCode(unicodeBomCharacterRune);
+
+    final Iterator<String> lineIterator = solutionContent.split('\n').iterator;
+    bool foundFlutterPluginsFolder = false;
+    bool foundNestedProjectsSection = false;
+    bool foundRunnerProject = false;
+    while (lineIterator.moveNext()) {
+      final Match projectStartMatch = projectStartPattern.firstMatch(lineIterator.current);
+      if (projectStartMatch != null) {
+        final String guid = projectStartMatch.group(2);
+        if (currentPlugins.contains(guid)) {
+          // Write an up-to-date version at this location (in case, e.g., the name
+          // has changed).
+          _writePluginProjectEntry(guid, currentPluginInfo[guid], newSolutionContent);
+          // Drop the old copy.
+          _skipUntil(lineIterator, projectEndPattern);
+          continue;
+        } else if (removedPlugins.contains(guid)) {
+          // Drop the stale plugin project.
+          _skipUntil(lineIterator, projectEndPattern);
+          continue;
+        } else if (projectStartMatch.group(1) == _project.vcprojFile.basename) {
+          foundRunnerProject = true;
+          // Update the Runner project's dependencies on the plugins.
+          // Skip to the dependencies section, or if there isn't one the end of
+          // the project.
+          while (!projectDependenciesStartPattern.hasMatch(lineIterator.current) &&
+              !projectEndPattern.hasMatch(lineIterator.current)) {
+            newSolutionContent.writeln(lineIterator.current);
+            lineIterator.moveNext();
+          }
+          // Add/update the dependencies section.
+          if (projectDependenciesStartPattern.hasMatch(lineIterator.current)) {
+            newSolutionContent.writeln(lineIterator.current);
+            _processSectionPluginReferences(removedPlugins, addedPlugins, lineIterator, _writeProjectDependency, newSolutionContent);
+          } else {
+            _writeDependenciesSection(currentPlugins, newSolutionContent);
+          }
+        }
+      }
+
+      if (pluginsFolderProjectStartPattern.hasMatch(lineIterator.current)) {
+          foundFlutterPluginsFolder = true;
+      }
+
+      if (globalStartPattern.hasMatch(lineIterator.current)) {
+        // The Global section is the end of the project list. Add any new plugins
+        // here, since the location VS will use is unknown. They will likely be
+        // reordered the next time VS writes the file.
+        for (final String guid in addedPlugins) {
+          _writePluginProjectEntry(guid, currentPluginInfo[guid], newSolutionContent);
+        }
+        // Also add the plugins folder if there wasn't already one.
+        if (!foundFlutterPluginsFolder) {
+          _writePluginFolderProjectEntry(newSolutionContent);
+        }
+      }
+
+      // Update the ProjectConfiguration section once it is reached.
+      if (globalSectionProjectConfigurationStartPattern.hasMatch(lineIterator.current)) {
+        newSolutionContent.writeln(lineIterator.current);
+        _processSectionPluginReferences(removedPlugins, addedPlugins, lineIterator, _writePluginConfigurationEntries, newSolutionContent);
+      }
+
+      // Update the NestedProjects section once it is reached.
+      if (globalSectionNestedProjectsStartPattern.hasMatch(lineIterator.current)) {
+        newSolutionContent.writeln(lineIterator.current);
+        _processSectionPluginReferences(removedPlugins, addedPlugins, lineIterator, _writePluginNestingEntry, newSolutionContent);
+        foundNestedProjectsSection = true;
+      }
+
+      // If there wasn't a NestedProjects global section, add one at the end.
+      if (!foundNestedProjectsSection && globalEndPattern.hasMatch(lineIterator.current)) {
+        newSolutionContent.writeln('\tGlobalSection(NestedProjects) = preSolution\r');
+        for (final String guid in currentPlugins) {
+          _writePluginNestingEntry(guid, newSolutionContent);
+        }
+        newSolutionContent.writeln('\tEndGlobalSection\r');
+      }
+
+      // Re-output anything that hasn't been explicitly skipped above.
+      newSolutionContent.writeln(lineIterator.current);
+    }
+
+    if (!foundRunnerProject) {
+      throwToolExit(
+          'Could not add plugins to Windows project:\n'
+          'Unable to find a "${_project.vcprojFile.basename}" project in ${_project.solutionFile.path}');
+    }
+
+    await _project.solutionFile.writeAsString(newSolutionContent.toString().trimRight());
+  }
+
+  /// Advances [iterator] it reaches an element that matches [pattern].
+  ///
+  /// Note that the current element at the time of calling is *not* checked.
+  void _skipUntil(Iterator<String> iterator, RegExp pattern) {
+    while (iterator.moveNext()) {
+      if (pattern.hasMatch(iterator.current)) {
+        return;
+      }
+    }
+  }
+
+  /// Writes the main project entry for the plugin with the given [guid] and
+  /// [name].
+  void _writePluginProjectEntry(String guid, String name, StringBuffer output) {
+    output.write('''
+Project("{$_kSolutionTypeGuidVcxproj}") = "$name", "Flutter\\ephemeral\\.plugin_symlinks\\$name\\windows\\plugin.vcxproj", "{$guid}"\r
+\tProjectSection(ProjectDependencies) = postProject\r
+\t\t{$_kFlutterBuildProjectGuid} = {$_kFlutterBuildProjectGuid}\r
+\tEndProjectSection\r
+EndProject\r
+''');
+  }
+
+  /// Writes the main project entry for the Flutter Plugins solution folder.
+  void _writePluginFolderProjectEntry(StringBuffer output) {
+    const String folderName = 'Flutter Plugins';
+    output.write('''
+Project("{$_kSolutionTypeGuidFolder}") = "$folderName", "$folderName", "{$_kFlutterPluginSolutionFolderGuid}"\r
+EndProject\r
+''');
+  }
+
+  /// Writes a project dependencies section, depending on all the GUIDs in
+  /// [dependencies].
+  void _writeDependenciesSection(Iterable<String> dependencies, StringBuffer output) {
+    output.writeln('ProjectSection(ProjectDependencies) = postProject\r');
+    for (final String guid in dependencies) {
+      _writeProjectDependency(guid, output);
+    }
+    output.writeln('EndProjectSection\r');
+  }
+
+  /// Returns the GUIDs of all the Flutter plugin projects in the given solution.
+  Set<String> _findPreviousPluginGuids(String solutionContent) {
+    // Find the plugin folder's known GUID in ProjectDependencies lines.
+    // Each line in that section has the form:
+    //   {project GUID} = {solution folder GUID}
+    final RegExp pluginFolderChildrenPattern = RegExp(
+        r'^\s*{([A-Fa-f0-9\-]*)}\s*=\s*{' + _kFlutterPluginSolutionFolderGuid + r'}\s*$',
+        multiLine: true,
+    );
+    return pluginFolderChildrenPattern
+        .allMatches(solutionContent)
+        .map((Match match) => match.group(1)).toSet();
+  }
+
+  /// Returns a mapping of plugin project GUID to name for all the Windows plugins
+  /// in [plugins].
+  Map<String, String> _getWindowsPluginNamesByGuid(List<Plugin> plugins) {
+    final Map<String, String> currentPluginInfo = <String, String>{};
+    for (final Plugin plugin in plugins) {
+      if (plugin.platforms.containsKey(_project.pluginConfigKey)) {
+        final _PluginProjectInfo info = _PluginProjectInfo(plugin, fileSystem: _fileSystem);
+        if (currentPluginInfo.containsKey(info.guid)) {
+          throwToolExit('The plugins "${currentPluginInfo[info.guid]}" and "${info.name}" '
+              'have the same ProjectGuid, which prevents them from being used together.\n\n'
+              'Please contact the plugin authors to resolve this, and/or remove one of the '
+              'plugins from your project.');
+        }
+        currentPluginInfo[info.guid] = info.name;
+      }
+    }
+    return currentPluginInfo;
+  }
+
+  /// Walks a GlobalSection or ProjectSection, removing entries related to removed
+  /// plugins and adding entries for new plugins at the end using
+  /// [newEntryWriter], which takes the guid of the plugin to write entries for.
+  ///
+  /// The caller is responsible for printing the section start line, which should
+  /// be [lineIterator.current] when this is called, and the section end line,
+  /// which will be [lineIterator.current] on return.
+  void _processSectionPluginReferences(
+      Set<String> removedPlugins,
+      Set<String> addedPlugins,
+      Iterator<String> lineIterator,
+      Function(String, StringBuffer) newEntryWriter,
+      StringBuffer output,
+  ) {
+    // Extracts the guid of the project that a line refers to. Currently all
+    // sections this function is used for start with "{project guid}", even though
+    // the rest of the line varies by section, so the pattern can currently be
+    // shared rather than parameterized.
+    final RegExp entryPattern = RegExp(r'^\s*{([A-Fa-f0-9\-]*)}');
+    final RegExp sectionEndPattern = RegExp(r'^\s*End\w*Section\s*$');
+    while (lineIterator.moveNext()) {
+      if (sectionEndPattern.hasMatch(lineIterator.current)) {
+        // The end of the section; add entries for new plugins, then exit.
+        for (final String guid in addedPlugins) {
+          newEntryWriter(guid, output);
+        }
+        return;
+      }
+      // Otherwise it's the sectino body. Drop any lines associated with old
+      // plugins, but pass everything else through as output.
+      final Match entryMatch = entryPattern.firstMatch(lineIterator.current);
+      if (entryMatch != null && removedPlugins.contains(entryMatch.group(1))) {
+        continue;
+      }
+      output.writeln(lineIterator.current);
+    }
+  }
+
+  /// Writes all the configuration entries for the plugin project with the given
+  /// [guid].
+  ///
+  /// Should be called within the context of writing
+  /// GlobalSection(ProjectConfigurationPlatforms).
+  void _writePluginConfigurationEntries(String guid, StringBuffer output) {
+    final List<String> configurations = <String>['Debug', 'Profile', 'Release'];
+    final List<String> entryTypes = <String>['ActiveCfg', 'Build.0'];
+    for (final String configuration in configurations) {
+      for (final String entryType in entryTypes) {
+        output.writeln('\t\t{$guid}.$configuration|x64.$entryType = $configuration|x64\r');
+      }
+    }
+  }
+
+  /// Writes the entries to nest the plugin projects with the given [guid] under
+  /// the Flutter Plugins solution folder.
+  ///
+  /// Should be called within the context of writing
+  /// GlobalSection(NestedProjects).
+  void _writePluginNestingEntry(String guid, StringBuffer output) {
+    output.writeln('\t\t{$guid} = {$_kFlutterPluginSolutionFolderGuid}\r');
+  }
+
+  /// Writes the entrie to make a project depend on another project with the
+  /// given [guid].
+  ///
+  /// Should be called within the context of writing
+  /// ProjectSection(ProjectDependencies).
+  void _writeProjectDependency(String guid, StringBuffer output) {
+    output.writeln('\t\t{$guid} = {$guid}\r');
+  }
+}

packages/flutter_tools/test/general.shard/plugins_test.dart

@@ -76,6 +76,7 @@ void main() {
       final Directory windowsManagedDirectory = flutterProject.directory.childDirectory('windows').childDirectory('flutter');
       when(windowsProject.managedDirectory).thenReturn(windowsManagedDirectory);
       when(windowsProject.vcprojFile).thenReturn(windowsManagedDirectory.parent.childFile('Runner.vcxproj'));
+      when(windowsProject.solutionFile).thenReturn(windowsManagedDirectory.parent.childFile('Runner.sln'));
       when(windowsProject.pluginSymlinkDirectory).thenReturn(windowsManagedDirectory.childDirectory('ephemeral').childDirectory('.plugin_symlinks'));
       when(windowsProject.generatedPluginPropertySheetFile).thenReturn(windowsManagedDirectory.childFile('GeneratedPlugins.props'));
       when(windowsProject.existsSync()).thenReturn(false);
@@ -309,6 +310,44 @@ dependencies:
       project.podManifestLock.createSync(recursive: true);
     }
 
+    // Creates a Windows solution file sufficient to allow plugin injection
+    // to run without failing.
+    void createDummyWindowsSolutionFile() {
+      windowsProject.solutionFile.createSync(recursive: true);
+      // This isn't a valid solution file, but it's just enough to work with the
+      // plugin injection.
+      windowsProject.solutionFile.writeAsStringSync('''
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "Runner", "Runner.vcxproj", "{3842E94C-E348-463A-ADBE-625A2B69B628}"
+	ProjectSection(ProjectDependencies) = postProject
+		{6419BF13-6ECD-4CD2-9E85-E566A1F03F8F} = {6419BF13-6ECD-4CD2-9E85-E566A1F03F8F}
+	EndProjectSection
+EndProject
+Global
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+	EndGlobalSection
+EndGlobal''');
+    }
+
+    // Creates a Windows project file for dummyPackageDirectory sufficient to
+    // allow plugin injection to run without failing.
+    void createDummyPluginWindowsProjectFile() {
+      final File projectFile = dummyPackageDirectory
+        .parent
+        .childDirectory('windows')
+        .childFile('plugin.vcxproj');
+      projectFile.createSync(recursive: true);
+      // This isn't a valid project file, but it's just enough to work with the
+      // plugin injection.
+      projectFile.writeAsStringSync('''
+<?xml version="1.0" encoding="utf-8"?>
+<Project DefaultTargets="Build" ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <PropertyGroup Label="Globals">
+    <ProjectGuid>{5919689F-A5D5-462C-AF50-D405CCEF89B8}</ProjectGuid>'}
+    <ProjectName>apackage</ProjectName>
+  </PropertyGroup>
+</Project>''');
+    }
+
     group('refreshPlugins', () {
       testUsingContext('Refreshing the plugin list is a no-op when the plugins list stays empty', () {
         refreshPluginsList(flutterProject);
@@ -837,6 +876,8 @@ web_plugin_with_nested:${webPluginWithNestedFile.childDirectory('lib').uri.toStr
         when(featureFlags.isWindowsEnabled).thenReturn(true);
         when(flutterProject.isModule).thenReturn(false);
         configureDummyPackageAsPlugin();
+        createDummyWindowsSolutionFile();
+        createDummyPluginWindowsProjectFile();
 
         await injectPlugins(flutterProject, checkProjects: true);
 
@@ -857,6 +898,8 @@ web_plugin_with_nested:${webPluginWithNestedFile.childDirectory('lib').uri.toStr
         when(featureFlags.isWindowsEnabled).thenReturn(true);
         when(flutterProject.isModule).thenReturn(false);
         configureDummyPackageAsPlugin();
+        createDummyWindowsSolutionFile();
+        createDummyPluginWindowsProjectFile();
 
         await injectPlugins(flutterProject, checkProjects: true);
 
@@ -871,6 +914,23 @@ web_plugin_with_nested:${webPluginWithNestedFile.childDirectory('lib').uri.toStr
         ProcessManager: () => FakeProcessManager.any(),
         FeatureFlags: () => featureFlags,
       });
+
+      testUsingContext('Injecting updates Windows solution file', () async {
+        when(windowsProject.existsSync()).thenReturn(true);
+        when(featureFlags.isWindowsEnabled).thenReturn(true);
+        when(flutterProject.isModule).thenReturn(false);
+        configureDummyPackageAsPlugin();
+        createDummyWindowsSolutionFile();
+        createDummyPluginWindowsProjectFile();
+
+        await injectPlugins(flutterProject, checkProjects: true);
+
+        expect(windowsProject.solutionFile.readAsStringSync(), contains(r'apackage\windows\plugin.vcxproj'));
+      }, overrides: <Type, Generator>{
+        FileSystem: () => fs,
+        ProcessManager: () => FakeProcessManager.any(),
+        FeatureFlags: () => featureFlags,
+      });
     });
 
     group('createPluginSymlinks', () {

packages/flutter_tools/test/general.shard/project_test.dart

@@ -225,6 +225,20 @@ void main() {
       testUsingContext('injects plugins for Windows', () async {
         final FlutterProject project = await someProject();
         project.windows.managedDirectory.createSync(recursive: true);
+        project.windows.solutionFile.createSync(recursive: true);
+        // Just enough solution file to allow injection to pass.
+        // TODO(stuartmorgan): Consider allowing injecting a mock solution util
+        // class into the test environment instead.
+        project.windows.solutionFile.writeAsStringSync('''
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "Runner", "Runner.vcxproj", "{3842E94C-E348-463A-ADBE-625A2B69B628}"
+	ProjectSection(ProjectDependencies) = postProject
+		{6419BF13-6ECD-4CD2-9E85-E566A1F03F8F} = {6419BF13-6ECD-4CD2-9E85-E566A1F03F8F}
+	EndProjectSection
+EndProject
+Global
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+	EndGlobalSection
+EndGlobal''');
         await project.ensureReadyForPlatformSpecificTooling();
         expectExists(project.windows.managedDirectory.childFile('generated_plugin_registrant.h'));
         expectExists(project.windows.managedDirectory.childFile('generated_plugin_registrant.cc'));

packages/flutter_tools/test/general.shard/windows/visual_studio_project_test.dart

+// Copyright 2014 The Flutter Authors. 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:file/memory.dart';
+import 'package:file_testing/file_testing.dart';
+import 'package:flutter_tools/src/base/file_system.dart';
+import 'package:flutter_tools/src/windows/visual_studio_project.dart';
+
+import '../../src/common.dart';
+
+void main() {
+  group('Visual Studio Project', () {
+    String generateProjectContents({String guid, String name}) {
+      // A bare-bones project.
+      return '''
+<?xml version="1.0" encoding="utf-8"?>
+<Project DefaultTargets="Build" ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <ItemGroup Label="ProjectConfigurations">
+    <ProjectConfiguration Include="Debug|x64">
+      <Configuration>Debug</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|x64">
+      <Configuration>Release</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+  </ItemGroup>
+  <PropertyGroup Label="Globals">
+    <VCProjectVersion>15.0</VCProjectVersion>
+    ${guid == null ? '' : '<ProjectGuid>{$guid}</ProjectGuid>'}
+    ${name == null ? '' : '<ProjectName>$name</ProjectName>'}
+    <WindowsTargetPlatformVersion>10.0</WindowsTargetPlatformVersion>
+  </PropertyGroup>
+  <Import Project="\$(VCTargetsPath)\\Microsoft.Cpp.Default.props" />
+  <PropertyGroup Label="Configuration">
+    <PlatformToolset>v142</PlatformToolset>
+  </PropertyGroup>
+  <Import Project="\$(VCTargetsPath)\\Microsoft.Cpp.props" />
+  <ImportGroup Label="ExtensionSettings">
+  </ImportGroup>
+  <ImportGroup Label="Shared">
+  </ImportGroup>
+  <ImportGroup Label="PropertySheets" />
+  <PropertyGroup Label="UserMacros" />
+  <PropertyGroup />
+  <ItemDefinitionGroup />
+  <ItemGroup>
+  </ItemGroup>
+  <Import Project="\$(VCTargetsPath)\\Microsoft.Cpp.targets" />
+  <ImportGroup Label="ExtensionTargets">
+  </ImportGroup>
+</Project>''';
+    }
+
+    test('Property extraction works on a simple vcxproj', () async {
+      final FileSystem fileSystem = MemoryFileSystem();
+      const String guid = '017C4BAC-FEBA-406D-8A2C-3099FFE9D811';
+      const String name = 'Test';
+      final File projectFile = fileSystem.file('aproject.vcxproj');
+      projectFile.writeAsStringSync(generateProjectContents(guid: guid, name: name));
+
+      final VisualStudioProject project = VisualStudioProject(projectFile, fileSystem: fileSystem);
+      expect(project.formatUnderstood, true);
+      expect(project.guid, guid);
+      expect(project.name, name);
+    });
+
+    test('Missing GUID returns null', () async {
+      final FileSystem fileSystem = MemoryFileSystem();
+      final File projectFile = fileSystem.file('aproject.vcxproj');
+      projectFile.writeAsStringSync(generateProjectContents());
+
+      final VisualStudioProject project = VisualStudioProject(projectFile, fileSystem: fileSystem);
+      expect(project.formatUnderstood, true);
+      expect(project.guid, null);
+    });
+
+    test('Missing project name uses filename', () async {
+      final FileSystem fileSystem = MemoryFileSystem();
+      final File projectFile = fileSystem.file('aproject.vcxproj');
+      projectFile.writeAsStringSync(generateProjectContents());
+
+      final VisualStudioProject project = VisualStudioProject(projectFile, fileSystem: fileSystem);
+      expect(project.formatUnderstood, true);
+      expect(project.name, 'aproject');
+    });
+
+    test('Unknown file contents creates an object, and return false for formatUnderstood', () async {
+      final FileSystem fileSystem = MemoryFileSystem();
+      final File projectFile = fileSystem.file('aproject.vcxproj');
+      projectFile.writeAsStringSync('This is not XML!');
+
+      final VisualStudioProject project = VisualStudioProject(projectFile, fileSystem: fileSystem);
+      expect(project.formatUnderstood, false);
+    });
+
+    test('Missing project file throws on creation', () async {
+      final FileSystem fileSystem = MemoryFileSystem();
+      final File projectFile = fileSystem.file('aproject.vcxproj');
+
+      expect(() => VisualStudioProject(projectFile, fileSystem: fileSystem), throwsFileSystemException());
+    });
+  });
+}

packages/flutter_tools/test/general.shard/windows/visual_studio_solution_utils_test.dart

+// Copyright 2014 The Flutter Authors. 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:file/memory.dart';
+import 'package:flutter_tools/src/base/file_system.dart';
+import 'package:flutter_tools/src/convert.dart';
+import 'package:flutter_tools/src/plugins.dart';
+import 'package:flutter_tools/src/platform_plugins.dart';
+import 'package:flutter_tools/src/project.dart';
+import 'package:flutter_tools/src/windows/visual_studio_solution_utils.dart';
+import 'package:mockito/mockito.dart';
+
+import '../../src/common.dart';
+
+void main() {
+  group('Visual Studio Solution Utils', () {
+    // Magic values; see visual_studio_solution_utils.dart.
+    const String solutionTypeGuidFolder = '2150E333-8FDC-42A3-9474-1A3956D46DE8';
+    const String solutionTypeGuidVcxproj = '8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942';
+    const String flutterPluginSolutionFolderGuid = '5C2E738A-1DD3-445A-AAC8-EEB9648DD07C';
+
+    // Arbitrary random GUIDs to use for fake plugins.
+    const String pluginAGuid = '9F200BC4-A747-43D1-8B72-B778F2C4D048';
+    const String pluginBGuid = '39AC79B8-28A6-4526-B5FF-9C83F59B3AF0';
+    const String pluginCGuid = '8E010714-28FF-416A-BC6F-9CDE336A02A7';
+    const String pluginDGuid = '304F1860-7E8B-4C99-8E1D-F5E55259F5C3';
+
+    FileSystem fs;
+    MockWindowsProject project;
+
+    setUp(() async {
+      fs = MemoryFileSystem(style: FileSystemStyle.windows);
+
+      project = MockWindowsProject();
+      when(project.pluginConfigKey).thenReturn('windows');
+      final Directory windowsManagedDirectory = fs.directory('C:').childDirectory('windows').childDirectory('flutter');
+      when(project.solutionFile).thenReturn(windowsManagedDirectory.parent.childFile('Runner.sln'));
+      when(project.vcprojFile).thenReturn(windowsManagedDirectory.parent.childFile('Runner.vcxproj'));
+      when(project.pluginSymlinkDirectory).thenReturn(windowsManagedDirectory.childDirectory('ephemeral').childDirectory('.plugin_symlinks'));
+    });
+
+    // Returns a solution file contents for a solution without any plugins.
+    void writeSolutionWithoutPlugins() {
+      project.solutionFile.createSync(recursive: true);
+      project.solutionFile.writeAsStringSync('''
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 16
+VisualStudioVersion = 16.0.29709.97
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "Runner", "Runner.vcxproj", "{3842E94C-E348-463A-ADBE-625A2B69B628}"
+	ProjectSection(ProjectDependencies) = postProject
+		{6419BF13-6ECD-4CD2-9E85-E566A1F03F8F} = {6419BF13-6ECD-4CD2-9E85-E566A1F03F8F}
+	EndProjectSection
+EndProject
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "Flutter Build", "FlutterBuild.vcxproj", "{6419BF13-6ECD-4CD2-9E85-E566A1F03F8F}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|x64 = Debug|x64
+		Profile|x64 = Profile|x64
+		Release|x64 = Release|x64
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{3842E94C-E348-463A-ADBE-625A2B69B628}.Debug|x64.ActiveCfg = Debug|x64
+		{3842E94C-E348-463A-ADBE-625A2B69B628}.Debug|x64.Build.0 = Debug|x64
+		{3842E94C-E348-463A-ADBE-625A2B69B628}.Profile|x64.ActiveCfg = Profile|x64
+		{3842E94C-E348-463A-ADBE-625A2B69B628}.Profile|x64.Build.0 = Profile|x64
+		{3842E94C-E348-463A-ADBE-625A2B69B628}.Release|x64.ActiveCfg = Release|x64
+		{3842E94C-E348-463A-ADBE-625A2B69B628}.Release|x64.Build.0 = Release|x64
+		{6419BF13-6ECD-4CD2-9E85-E566A1F03F8F}.Debug|x64.ActiveCfg = Debug|x64
+		{6419BF13-6ECD-4CD2-9E85-E566A1F03F8F}.Debug|x64.Build.0 = Debug|x64
+		{6419BF13-6ECD-4CD2-9E85-E566A1F03F8F}.Profile|x64.ActiveCfg = Profile|x64
+		{6419BF13-6ECD-4CD2-9E85-E566A1F03F8F}.Profile|x64.Build.0 = Profile|x64
+		{6419BF13-6ECD-4CD2-9E85-E566A1F03F8F}.Release|x64.ActiveCfg = Release|x64
+		{6419BF13-6ECD-4CD2-9E85-E566A1F03F8F}.Release|x64.Build.0 = Release|x64
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {B8A69CB0-A974-4774-9EBD-1E5EECACD186}
+	EndGlobalSection
+EndGlobal''');
+    }
+
+    // Returns a solution file contents for a solution with plugins A, B, and C
+    // already added.
+    void writeSolutionWithPlugins() {
+      const String pluginSymlinkSubdirPath = r'Flutter\ephemeral\.plugin_symlinks';
+      const String pluginProjectSubpath = r'windows\plugin.vcxproj';
+      project.solutionFile.createSync(recursive: true);
+      project.solutionFile.writeAsStringSync('''
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 16
+VisualStudioVersion = 16.0.29709.97
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "Runner", "Runner.vcxproj", "{5A827760-CF8B-408A-99A3-B6C0AD2271E7}"
+	ProjectSection(ProjectDependencies) = postProject
+		{$pluginAGuid} = {$pluginAGuid}
+		{6419BF13-6ECD-4CD2-9E85-E566A1F03F8F} = {6419BF13-6ECD-4CD2-9E85-E566A1F03F8F}
+		{$pluginBGuid} = {$pluginBGuid}
+		{$pluginCGuid} = {$pluginCGuid}
+	EndProjectSection
+EndProject
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "plugin_a", "$pluginSymlinkSubdirPath\\plugin_a\\$pluginProjectSubpath", "{$pluginAGuid}"
+	ProjectSection(ProjectDependencies) = postProject
+		{6419BF13-6ECD-4CD2-9E85-E566A1F03F8F} = {6419BF13-6ECD-4CD2-9E85-E566A1F03F8F}
+	EndProjectSection
+EndProject
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "Flutter Build", "FlutterBuild.vcxproj", "{6419BF13-6ECD-4CD2-9E85-E566A1F03F8F}"
+EndProject
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "plugin_b", "$pluginSymlinkSubdirPath\\plugin_b\\$pluginProjectSubpath", "{$pluginBGuid}"
+	ProjectSection(ProjectDependencies) = postProject
+		{6419BF13-6ECD-4CD2-9E85-E566A1F03F8F} = {6419BF13-6ECD-4CD2-9E85-E566A1F03F8F}
+	EndProjectSection
+EndProject
+Project("{8BC9CEB8-8B4A-11D0-8D11-00A0C91BC942}") = "plugin_c", "$pluginSymlinkSubdirPath\\plugin_c\\$pluginProjectSubpath", "{$pluginCGuid}"
+	ProjectSection(ProjectDependencies) = postProject
+		{6419BF13-6ECD-4CD2-9E85-E566A1F03F8F} = {6419BF13-6ECD-4CD2-9E85-E566A1F03F8F}
+	EndProjectSection
+EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Flutter Plugins", "Flutter Plugins", "{5C2E738A-1DD3-445A-AAC8-EEB9648DD07C}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|x64 = Debug|x64
+		Profile|x64 = Profile|x64
+		Release|x64 = Release|x64
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{5A827760-CF8B-408A-99A3-B6C0AD2271E7}.Debug|x64.ActiveCfg = Debug|x64
+		{5A827760-CF8B-408A-99A3-B6C0AD2271E7}.Debug|x64.Build.0 = Debug|x64
+		{5A827760-CF8B-408A-99A3-B6C0AD2271E7}.Profile|x64.ActiveCfg = Profile|x64
+		{5A827760-CF8B-408A-99A3-B6C0AD2271E7}.Profile|x64.Build.0 = Profile|x64
+		{5A827760-CF8B-408A-99A3-B6C0AD2271E7}.Release|x64.ActiveCfg = Release|x64
+		{5A827760-CF8B-408A-99A3-B6C0AD2271E7}.Release|x64.Build.0 = Release|x64
+		{$pluginAGuid}.Debug|x64.ActiveCfg = Debug|x64
+		{$pluginAGuid}.Debug|x64.Build.0 = Debug|x64
+		{$pluginAGuid}.Profile|x64.ActiveCfg = Profile|x64
+		{$pluginAGuid}.Profile|x64.Build.0 = Profile|x64
+		{$pluginAGuid}.Release|x64.ActiveCfg = Release|x64
+		{$pluginAGuid}.Release|x64.Build.0 = Release|x64
+		{6419BF13-6ECD-4CD2-9E85-E566A1F03F8F}.Debug|x64.ActiveCfg = Debug|x64
+		{6419BF13-6ECD-4CD2-9E85-E566A1F03F8F}.Debug|x64.Build.0 = Debug|x64
+		{6419BF13-6ECD-4CD2-9E85-E566A1F03F8F}.Profile|x64.ActiveCfg = Profile|x64
+		{6419BF13-6ECD-4CD2-9E85-E566A1F03F8F}.Profile|x64.Build.0 = Profile|x64
+		{6419BF13-6ECD-4CD2-9E85-E566A1F03F8F}.Release|x64.ActiveCfg = Release|x64
+		{6419BF13-6ECD-4CD2-9E85-E566A1F03F8F}.Release|x64.Build.0 = Release|x64
+		{$pluginBGuid}.Debug|x64.ActiveCfg = Debug|x64
+		{$pluginBGuid}.Debug|x64.Build.0 = Debug|x64
+		{$pluginBGuid}.Profile|x64.ActiveCfg = Profile|x64
+		{$pluginBGuid}.Profile|x64.Build.0 = Profile|x64
+		{$pluginBGuid}.Release|x64.ActiveCfg = Release|x64
+		{$pluginBGuid}.Release|x64.Build.0 = Release|x64
+		{$pluginCGuid}.Debug|x64.ActiveCfg = Debug|x64
+		{$pluginCGuid}.Debug|x64.Build.0 = Debug|x64
+		{$pluginCGuid}.Profile|x64.ActiveCfg = Profile|x64
+		{$pluginCGuid}.Profile|x64.Build.0 = Profile|x64
+		{$pluginCGuid}.Release|x64.ActiveCfg = Release|x64
+		{$pluginCGuid}.Release|x64.Build.0 = Release|x64
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(NestedProjects) = preSolution
+		{$pluginCGuid} = {$flutterPluginSolutionFolderGuid}
+		{$pluginBGuid} = {$flutterPluginSolutionFolderGuid}
+		{$pluginAGuid} = {$flutterPluginSolutionFolderGuid}
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {6C8A8041-10D8-4BEB-B73D-C02BCE62120B}
+	EndGlobalSection
+EndGlobal''');
+    }
+
+    void writeDummyPluginProject(String pluginName, String guid) {
+      final File pluginProjectFile = project.pluginSymlinkDirectory
+          .childDirectory(pluginName)
+          .childDirectory('windows')
+          .childFile('plugin.vcxproj');
+      pluginProjectFile.createSync(recursive: true);
+      pluginProjectFile.writeAsStringSync('''
+<?xml version="1.0" encoding="utf-8"?>
+<Project DefaultTargets="Build" ToolsVersion="15.0" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <ItemGroup Label="ProjectConfigurations">
+    <ProjectConfiguration Include="Debug|x64">
+      <Configuration>Debug</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+    <ProjectConfiguration Include="Release|x64">
+      <Configuration>Release</Configuration>
+      <Platform>x64</Platform>
+    </ProjectConfiguration>
+  </ItemGroup>
+  <PropertyGroup Label="Globals">
+    <VCProjectVersion>15.0</VCProjectVersion>
+    <ProjectGuid>{$guid}</ProjectGuid>
+    <ProjectName>$pluginName</ProjectName>
+    <WindowsTargetPlatformVersion>10.0</WindowsTargetPlatformVersion>
+  </PropertyGroup>
+  <Import Project="\$(VCTargetsPath)\\Microsoft.Cpp.Default.props" />
+  <PropertyGroup Label="Configuration">
+    <PlatformToolset>v142</PlatformToolset>
+  </PropertyGroup>
+  <Import Project="\$(VCTargetsPath)\\Microsoft.Cpp.props" />
+  <ImportGroup Label="ExtensionSettings">
+  </ImportGroup>
+  <ImportGroup Label="Shared">
+  </ImportGroup>
+  <ImportGroup Label="PropertySheets" />
+  <PropertyGroup Label="UserMacros" />
+  <PropertyGroup />
+  <ItemDefinitionGroup />
+  <ItemGroup>
+  </ItemGroup>
+  <Import Project="\$(VCTargetsPath)\\Microsoft.Cpp.targets" />
+  <ImportGroup Label="ExtensionTargets">
+  </ImportGroup>
+</Project>''');
+    }
+
+    // Configures and returns a mock plugin with the given name and GUID in the
+    // project's plugin symlink directory.
+    Plugin getMockPlugin(String name, String guid) {
+      final MockPlugin plugin = MockPlugin();
+      when(plugin.platforms).thenReturn(<String, PluginPlatform>{project.pluginConfigKey: null});
+      when(plugin.name).thenReturn(name);
+      when(plugin.path).thenReturn(project.pluginSymlinkDirectory.childDirectory(name).path);
+      writeDummyPluginProject(name, guid);
+      return plugin;
+    }
+
+    test('Adding the first plugin to a solution adds the expected references', () async {
+      writeSolutionWithoutPlugins();
+
+      final List<Plugin> plugins = <Plugin>[
+        getMockPlugin('plugin_a', pluginAGuid),
+      ];
+      await VisualStudioSolutionUtils(project: project, fileSystem: fs).updatePlugins(plugins);
+
+      final String newSolutionContents = project.solutionFile.readAsStringSync();
+
+      // Check for:
+      // - Plugin project.
+      final String pluginSubpath = fs.path.join('Flutter', 'ephemeral', '.plugin_symlinks', 'plugin_a', 'windows', 'plugin.vcxproj');
+      expect(newSolutionContents, contains('Project("{$solutionTypeGuidVcxproj}") = "plugin_a", "$pluginSubpath", "{$pluginAGuid}"'));
+      // - A dependency on the plugin project (from the Runner).
+      expect(newSolutionContents, contains('{$pluginAGuid} = {$pluginAGuid}'));
+      // - Plugin project configurations.
+      expect(newSolutionContents, contains('{$pluginAGuid}.Debug|x64.ActiveCfg = Debug|x64'));
+      expect(newSolutionContents, contains('{$pluginAGuid}.Debug|x64.Build.0 = Debug|x64'));
+      expect(newSolutionContents, contains('{$pluginAGuid}.Profile|x64.ActiveCfg = Profile|x64'));
+      expect(newSolutionContents, contains('{$pluginAGuid}.Profile|x64.Build.0 = Profile|x64'));
+      expect(newSolutionContents, contains('{$pluginAGuid}.Release|x64.ActiveCfg = Release|x64'));
+      expect(newSolutionContents, contains('{$pluginAGuid}.Release|x64.Build.0 = Release|x64'));
+      // - A plugin folder, and a child reference for the plugin.
+      expect(newSolutionContents, contains('Project("{$solutionTypeGuidFolder}") = "Flutter Plugins", "Flutter Plugins", "{$flutterPluginSolutionFolderGuid}"'));
+      expect(newSolutionContents, contains('{$pluginAGuid} = {$flutterPluginSolutionFolderGuid}'));
+    });
+
+    test('Removing a plugin removes entries as expected', () async {
+      writeSolutionWithPlugins();
+
+      final List<Plugin> plugins = <Plugin>[
+        getMockPlugin('plugin_a', pluginAGuid),
+        getMockPlugin('plugin_c', pluginCGuid),
+      ];
+      await VisualStudioSolutionUtils(project: project, fileSystem: fs).updatePlugins(plugins);
+
+      final String newSolutionContents = project.solutionFile.readAsStringSync();
+
+      // There should be no references to plugin B anywhere.
+      expect(newSolutionContents.contains(pluginBGuid), false);
+
+      // All the plugin A & C references should still be present in modified
+      // sections.
+      for (final String guid in <String>[pluginAGuid, pluginCGuid]) {
+        expect(newSolutionContents, contains('{$guid} = {$guid}'));
+        expect(newSolutionContents, contains('{$guid}.Debug|x64.ActiveCfg = Debug|x64'));
+        expect(newSolutionContents, contains('{$guid} = {$flutterPluginSolutionFolderGuid}'));
+      }
+    });
+
+    test('Removing all plugins works', () async {
+      writeSolutionWithPlugins();
+
+      final List<Plugin> plugins = <Plugin>[
+      ];
+      await VisualStudioSolutionUtils(project: project, fileSystem: fs).updatePlugins( plugins);
+
+      final String newSolutionContents = project.solutionFile.readAsStringSync();
+
+      // There should be no references to any of the plugins.
+      expect(newSolutionContents.contains(pluginAGuid), false);
+      expect(newSolutionContents.contains(pluginBGuid), false);
+      expect(newSolutionContents.contains(pluginCGuid), false);
+      // Nor any plugins in the Flutter Plugins folder.
+      expect(newSolutionContents.contains('= {$flutterPluginSolutionFolderGuid}'), false);
+    });
+
+    test('Adjusting the plugin list by adding and removing adjusts entries as expected', () async {
+      writeSolutionWithPlugins();
+
+      final List<Plugin> plugins = <Plugin>[
+        getMockPlugin('plugin_b', pluginBGuid),
+        getMockPlugin('plugin_c', pluginCGuid),
+        getMockPlugin('plugin_d', pluginDGuid),
+      ];
+      await VisualStudioSolutionUtils(project: project, fileSystem: fs).updatePlugins(plugins);
+
+      final String newSolutionContents = project.solutionFile.readAsStringSync();
+
+      // There should be no references to plugin A anywhere.
+      expect(newSolutionContents.contains(pluginAGuid), false);
+
+      // All the plugin B & C references should still be present in modified
+      // sections.
+      for (final String guid in <String>[pluginBGuid, pluginCGuid]) {
+        expect(newSolutionContents, contains('{$guid} = {$guid}'));
+        expect(newSolutionContents, contains('{$guid}.Debug|x64.ActiveCfg = Debug|x64'));
+        expect(newSolutionContents, contains('{$guid} = {$flutterPluginSolutionFolderGuid}'));
+      }
+
+      // All the plugin D values should be added:
+      // - Plugin project.
+      final String pluginSubpath = fs.path.join('Flutter', 'ephemeral', '.plugin_symlinks', 'plugin_d', 'windows', 'plugin.vcxproj');
+      expect(newSolutionContents, contains('Project("{$solutionTypeGuidVcxproj}") = "plugin_d", "$pluginSubpath", "{$pluginDGuid}"'));
+      // - A dependency on the plugin project (from the Runner).
+      expect(newSolutionContents, contains('{$pluginDGuid} = {$pluginDGuid}'));
+      // - Plugin project configurations.
+      expect(newSolutionContents, contains('{$pluginDGuid}.Debug|x64.ActiveCfg = Debug|x64'));
+      expect(newSolutionContents, contains('{$pluginDGuid}.Debug|x64.Build.0 = Debug|x64'));
+      expect(newSolutionContents, contains('{$pluginDGuid}.Profile|x64.ActiveCfg = Profile|x64'));
+      expect(newSolutionContents, contains('{$pluginDGuid}.Profile|x64.Build.0 = Profile|x64'));
+      expect(newSolutionContents, contains('{$pluginDGuid}.Release|x64.ActiveCfg = Release|x64'));
+      expect(newSolutionContents, contains('{$pluginDGuid}.Release|x64.Build.0 = Release|x64'));
+      // - A child reference for the plugin in the Flutter Plugins folder.
+      expect(newSolutionContents, contains('{$pluginDGuid} = {$flutterPluginSolutionFolderGuid}'));
+    });
+
+    test('Adding plugins doesn\'t create duplicate entries', () async {
+      writeSolutionWithPlugins();
+
+      final List<Plugin> plugins = <Plugin>[
+        getMockPlugin('plugin_a', pluginAGuid),
+        getMockPlugin('plugin_b', pluginBGuid),
+        getMockPlugin('plugin_c', pluginCGuid),
+        getMockPlugin('plugin_d', pluginDGuid),
+      ];
+      await VisualStudioSolutionUtils(project: project, fileSystem: fs).updatePlugins(plugins);
+
+      final String newSolutionContents = project.solutionFile.readAsStringSync();
+      // There should only be:
+      // - one Flutter Plugins folder.
+      expect('Project("{$solutionTypeGuidFolder}")'.allMatches(newSolutionContents).length, 1);
+      // - one copy of plugin A's project.
+      expect('Project("{$solutionTypeGuidVcxproj}") = "plugin_a"'.allMatches(newSolutionContents).length, 1);
+      // - one copy of plugin A's configuration entries.
+      expect('{$pluginAGuid}.Debug|x64.ActiveCfg = Debug|x64'.allMatches(newSolutionContents).length, 1);
+      // - one dependency from the Runner to plugin A.
+      expect('{$pluginAGuid} = {$pluginAGuid}'.allMatches(newSolutionContents).length, 1);
+      // - one copy of plugin A in Flutter Plugins.
+      expect('{$pluginAGuid} = {$flutterPluginSolutionFolderGuid}'.allMatches(newSolutionContents).length, 1);
+    });
+
+    test('Adding plugins doesn\'t change ordering', () async {
+      writeSolutionWithPlugins();
+
+      final List<Plugin> plugins = <Plugin>[
+        getMockPlugin('plugin_a', pluginAGuid),
+        getMockPlugin('plugin_b', pluginBGuid),
+        getMockPlugin('plugin_c', pluginCGuid),
+        getMockPlugin('plugin_d', pluginDGuid),
+      ];
+      await VisualStudioSolutionUtils(project: project, fileSystem: fs).updatePlugins(plugins);
+
+      final String newSolutionContents = project.solutionFile.readAsStringSync();
+      // Plugin A should still be before Flutter Build in the Runner dependencies.
+      expect(newSolutionContents.indexOf('{$pluginAGuid} = {$pluginAGuid}'),
+          lessThan(newSolutionContents.indexOf('{6419BF13-6ECD-4CD2-9E85-E566A1F03F8F} = {6419BF13-6ECD-4CD2-9E85-E566A1F03F8F}')));
+      // ... and in the build configuration list.
+      expect(newSolutionContents.indexOf('{$pluginAGuid}.Debug|x64.ActiveCfg = Debug|x64'),
+          lessThan(newSolutionContents.indexOf('{6419BF13-6ECD-4CD2-9E85-E566A1F03F8F}.Debug|x64.ActiveCfg = Debug|x64')));
+      // And plugin C should still be before plugin A in the Flutter Plugins nesting list.
+      expect(newSolutionContents.indexOf('{$pluginCGuid} = {$flutterPluginSolutionFolderGuid}'),
+          lessThan(newSolutionContents.indexOf('{$pluginAGuid} = {$flutterPluginSolutionFolderGuid}')));
+    });
+
+    test('Updating solution preserves BOM', () async {
+      writeSolutionWithPlugins();
+
+      final List<Plugin> plugins = <Plugin>[];
+      await VisualStudioSolutionUtils(project: project, fileSystem: fs).updatePlugins(plugins);
+
+      // Visual Studio expects sln files to start with a BOM.
+      final List<int> solutionStartingBytes = project.solutionFile.readAsBytesSync().take(3).toList();
+      final List<int> bomBytes = utf8.encode(String.fromCharCode(unicodeBomCharacterRune));
+      expect(solutionStartingBytes, bomBytes);
+    });
+
+    test('Updating solution dosen\'t introduce unexpected whitespace', () async {
+      writeSolutionWithPlugins();
+
+      final List<Plugin> plugins = <Plugin>[
+        getMockPlugin('plugin_a', pluginAGuid),
+        getMockPlugin('plugin_b', pluginBGuid),
+      ];
+      await VisualStudioSolutionUtils(project: project, fileSystem: fs).updatePlugins(plugins);
+
+      final String newSolutionContents = project.solutionFile.readAsStringSync();
+      // Project, EndProject, Global, and EndGlobal should be at the start of
+      // lines.
+      expect(RegExp(r'^[ \t]+Project\(', multiLine: true).hasMatch(newSolutionContents), false);
+      expect(RegExp(r'^[ \t]+EndProject\s*$', multiLine: true).hasMatch(newSolutionContents), false);
+      expect(RegExp(r'^[ \t]+Global\s*$', multiLine: true).hasMatch(newSolutionContents), false);
+      expect(RegExp(r'^[ \t]+EndGlobal\s*$', multiLine: true).hasMatch(newSolutionContents), false);
+      // ProjectSection, GlobalSection, and their ends should be indented
+      // exactly one tab.
+      expect(RegExp(r'^([ \t]+\t|\t[ \t]+)ProjectSection\(', multiLine: true).hasMatch(newSolutionContents), false);
+      expect(RegExp(r'^([ \t]+\t|\t[ \t]+)EndProjectSection\s*$', multiLine: true).hasMatch(newSolutionContents), false);
+      expect(RegExp(r'^([ \t]+\t|\t[ \t]+)GlobalSection\(\s*$', multiLine: true).hasMatch(newSolutionContents), false);
+      expect(RegExp(r'^([ \t]+\t|\t[ \t]+)EndGlobalSection\s*$', multiLine: true).hasMatch(newSolutionContents), false);
+    });
+  });
+}
+
+class MockWindowsProject extends Mock implements WindowsProject {}
+class MockPlugin extends Mock implements Plugin {}