[flutter_plugin_tools] Migrate java-test to new base command (#4105)

Switches `java-test` to the new base command that handles the boilerplate of looping over target packages.

Includes test improvements:
- Adds failure tests; previously no failure cases were covered.
- Captures output so test output isn't spammed with command output.

Part of flutter/flutter#83413

script/tool/lib/src/java_test_command.dart

@@ -6,17 +6,19 @@ import 'package:file/file.dart';
 import 'package:path/path.dart' as p;
 
 import 'common/core.dart';
-import 'common/plugin_command.dart';
+import 'common/package_looping_command.dart';
 import 'common/process_runner.dart';
 
 /// A command to run the Java tests of Android plugins.
-class JavaTestCommand extends PluginCommand {
+class JavaTestCommand extends PackageLoopingCommand {
   /// Creates an instance of the test runner.
   JavaTestCommand(
     Directory packagesDir, {
     ProcessRunner processRunner = const ProcessRunner(),
   }) : super(packagesDir, processRunner: processRunner);
 
+  static const String _gradleWrapper = 'gradlew';
+
   @override
   final String name = 'java-test';
 
@@ -25,12 +27,10 @@ class JavaTestCommand extends PluginCommand {
       'Building the apks of the example apps is required before executing this'
       'command.';
 
-  static const String _gradleWrapper = 'gradlew';
-
   @override
-  Future<void> run() async {
-    final Stream<Directory> examplesWithTests = getExamples().where(
-        (Directory d) =>
+  Future<List<String>> runForPackage(Directory package) async {
+    final Iterable<Directory> examplesWithTests = getExamplesForPlugin(package)
+        .where((Directory d) =>
             isFlutterPackage(d) &&
             (d
                     .childDirectory('android')
@@ -44,18 +44,17 @@ class JavaTestCommand extends PluginCommand {
                     .childDirectory('test')
                     .existsSync()));
 
-    final List<String> failingPackages = <String>[];
-    final List<String> missingFlutterBuild = <String>[];
-    await for (final Directory example in examplesWithTests) {
-      final String packageName =
-          p.relative(example.path, from: packagesDir.path);
-      print('\nRUNNING JAVA TESTS for $packageName');
+    final List<String> errors = <String>[];
+    for (final Directory example in examplesWithTests) {
+      final String exampleName = p.relative(example.path, from: package.path);
+      print('\nRUNNING JAVA TESTS for $exampleName');
 
       final Directory androidDirectory = example.childDirectory('android');
       if (!androidDirectory.childFile(_gradleWrapper).existsSync()) {
-        print('ERROR: Run "flutter build apk" on example app of $packageName'
+        printError('ERROR: Run "flutter build apk" on $exampleName, or run '
+            'this tool\'s "build-examples --apk" command, '
             'before executing tests.');
-        missingFlutterBuild.add(packageName);
+        errors.add('$exampleName has not been built.');
         continue;
       }
 
@@ -64,31 +63,9 @@ class JavaTestCommand extends PluginCommand {
           <String>['testDebugUnitTest', '--info'],
           workingDir: androidDirectory);
       if (exitCode != 0) {
-        failingPackages.add(packageName);
+        errors.add('$exampleName tests failed.');
       }
     }
-
-    print('\n\n');
-    if (failingPackages.isNotEmpty) {
-      print(
-          'The Java tests for the following packages are failing (see above for'
-          'details):');
-      for (final String package in failingPackages) {
-        print(' * $package');
-      }
-    }
-    if (missingFlutterBuild.isNotEmpty) {
-      print('Run "pub global run flutter_plugin_tools build-examples --apk" on'
-          'the following packages before executing tests again:');
-      for (final String package in missingFlutterBuild) {
-        print(' * $package');
-      }
-    }
-
-    if (failingPackages.isNotEmpty || missingFlutterBuild.isNotEmpty) {
-      throw ToolExit(1);
-    }
-
-    print('All Java tests successful!');
+    return errors;
   }
 }