[flutter_plugin_tools] Remove global state from tests (#4018)

Eliminates the global test filesystem and global test packages directory, in favor of local versions. This guarantees that each test runs with a clean filesystem state, rather than relying on cleanup. It also simplifies understanding the tests, since everything is done via params and return values instead of needing to know about the magic global variables and which methods mutate them.

Author: stuartmorgan-g

script/tool/test/analyze_command_test.dart

@@ -4,6 +4,7 @@
 
 import 'package:args/command_runner.dart';
 import 'package:file/file.dart';
+import 'package:file/memory.dart';
 import 'package:flutter_plugin_tools/src/analyze_command.dart';
 import 'package:flutter_plugin_tools/src/common.dart';
 import 'package:test/test.dart';
@@ -12,26 +13,25 @@ import 'mocks.dart';
 import 'util.dart';
 
 void main() {
+  late FileSystem fileSystem;
+  late Directory packagesDir;
   late RecordingProcessRunner processRunner;
   late CommandRunner<void> runner;
 
   setUp(() {
-    initializeFakePackages();
+    fileSystem = MemoryFileSystem();
+    packagesDir = createPackagesDirectory(fileSystem: fileSystem);
     processRunner = RecordingProcessRunner();
     final AnalyzeCommand analyzeCommand =
-        AnalyzeCommand(mockPackagesDir, processRunner: processRunner);
+        AnalyzeCommand(packagesDir, processRunner: processRunner);
 
     runner = CommandRunner<void>('analyze_command', 'Test for analyze_command');
     runner.addCommand(analyzeCommand);
   });
 
-  tearDown(() {
-    mockPackagesDir.deleteSync(recursive: true);
-  });
-
   test('analyzes all packages', () async {
-    final Directory plugin1Dir = createFakePlugin('a');
-    final Directory plugin2Dir = createFakePlugin('b');
+    final Directory plugin1Dir = createFakePlugin('a', packagesDir);
+    final Directory plugin2Dir = createFakePlugin('b', packagesDir);
 
     final MockProcess mockProcess = MockProcess();
     mockProcess.exitCodeCompleter.complete(0);
@@ -53,7 +53,8 @@ void main() {
   });
 
   test('skips flutter pub get for examples', () async {
-    final Directory plugin1Dir = createFakePlugin('a', withSingleExample: true);
+    final Directory plugin1Dir =
+        createFakePlugin('a', packagesDir, withSingleExample: true);
 
     final MockProcess mockProcess = MockProcess();
     mockProcess.exitCodeCompleter.complete(0);
@@ -71,8 +72,8 @@ void main() {
   });
 
   test('don\'t elide a non-contained example package', () async {
-    final Directory plugin1Dir = createFakePlugin('a');
-    final Directory plugin2Dir = createFakePlugin('example');
+    final Directory plugin1Dir = createFakePlugin('a', packagesDir);
+    final Directory plugin2Dir = createFakePlugin('example', packagesDir);
 
     final MockProcess mockProcess = MockProcess();
     mockProcess.exitCodeCompleter.complete(0);
@@ -94,7 +95,7 @@ void main() {
   });
 
   test('uses a separate analysis sdk', () async {
-    final Directory pluginDir = createFakePlugin('a');
+    final Directory pluginDir = createFakePlugin('a', packagesDir);
 
     final MockProcess mockProcess = MockProcess();
     mockProcess.exitCodeCompleter.complete(0);
@@ -120,7 +121,7 @@ void main() {
 
   group('verifies analysis settings', () {
     test('fails analysis_options.yaml', () async {
-      createFakePlugin('foo', withExtraFiles: <List<String>>[
+      createFakePlugin('foo', packagesDir, withExtraFiles: <List<String>>[
         <String>['analysis_options.yaml']
       ]);
 
@@ -129,7 +130,7 @@ void main() {
     });
 
     test('fails .analysis_options', () async {
-      createFakePlugin('foo', withExtraFiles: <List<String>>[
+      createFakePlugin('foo', packagesDir, withExtraFiles: <List<String>>[
         <String>['.analysis_options']
       ]);
 
@@ -139,7 +140,7 @@ void main() {
 
     test('takes an allow list', () async {
       final Directory pluginDir =
-          createFakePlugin('foo', withExtraFiles: <List<String>>[
+          createFakePlugin('foo', packagesDir, withExtraFiles: <List<String>>[
         <String>['analysis_options.yaml']
       ]);
 
@@ -160,7 +161,7 @@ void main() {
 
     // See: https://github.com/flutter/flutter/issues/78994
     test('takes an empty allow list', () async {
-      createFakePlugin('foo', withExtraFiles: <List<String>>[
+      createFakePlugin('foo', packagesDir, withExtraFiles: <List<String>>[
         <String>['analysis_options.yaml']
       ]);