From 771a07bfe9e8df8214ddd0eae579e79dba8c298e Mon Sep 17 00:00:00 2001
From: Matan Lurey <matan@lurey.org>
Date: Wed, 15 May 2024 16:38:29 -0700
Subject: [PATCH 1/6] Include stdout on a failed gn desc call.

---
 tools/engine_tool/lib/src/gn.dart   |  12 ++-
 tools/engine_tool/test/gn_test.dart | 112 ++++++++++++++++++++++++++++
 2 files changed, 123 insertions(+), 1 deletion(-)
 create mode 100644 tools/engine_tool/test/gn_test.dart

diff --git a/tools/engine_tool/lib/src/gn.dart b/tools/engine_tool/lib/src/gn.dart
index 986c47c20a04a..b8812dffc7194 100644
--- a/tools/engine_tool/lib/src/gn.dart
+++ b/tools/engine_tool/lib/src/gn.dart
@@ -67,7 +67,7 @@ interface class Gn {
       result = JsonObject.parse(process.stdout);
     } on FormatException catch (e) {
       _environment.logger.fatal(
-        'Failed to parse JSON output from `gn desc`:\n$e',
+        'Failed to parse JSON output from `gn desc`:\n$e\n${process.stdout}',
       );
     }
 
@@ -136,6 +136,10 @@ sealed class BuildTarget {
   @mustBeOverridden
   @override
   int get hashCode;
+
+  @mustBeOverridden
+  @override
+  String toString();
 }
 
 /// A build target that produces a [shared library][] or [static library][].
@@ -158,6 +162,9 @@ final class LibraryBuildTarget extends BuildTarget {
 
   @override
   int get hashCode => Object.hash(label, testOnly);
+
+  @override
+  String toString() => 'LibraryBuildTarget($label, testOnly=$testOnly)';
 }
 
 /// A build target that produces an [executable][] program.
@@ -184,4 +191,7 @@ final class ExecutableBuildTarget extends BuildTarget {
 
   @override
   int get hashCode => Object.hash(label, testOnly, executable);
+
+  @override
+  String toString() => 'ExecutableBuildTarget($label, testOnly=$testOnly, executable=$executable)';
 }
diff --git a/tools/engine_tool/test/gn_test.dart b/tools/engine_tool/test/gn_test.dart
new file mode 100644
index 0000000000000..8bebbd335c7ab
--- /dev/null
+++ b/tools/engine_tool/test/gn_test.dart
@@ -0,0 +1,112 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:engine_tool/src/gn.dart';
+import 'package:engine_tool/src/label.dart';
+import 'package:litetest/litetest.dart';
+
+import 'utils.dart';
+
+void main() {
+  test('gn.desc handles a non-zero exit code', () async {
+    final TestEnvironment testEnv = TestEnvironment.withTestEngine(
+      cannedProcesses: <CannedProcess>[
+        CannedProcess(
+          (List<String> command) => command.contains('desc'),
+          exitCode: 1,
+          stdout: 'stdout',
+          stderr: 'stderr',
+        ),
+      ],
+    );
+    try {
+      final Gn gn = Gn.fromEnvironment(testEnv.environment);
+      await gn.desc('out/Release', TargetPattern('//foo', 'bar'));
+      fail('Expected an exception');
+    } catch (e) {
+      final String message = '$e';
+      expect(message, contains('Failed to run'));
+      expect(message, contains('exit code 1'));
+      expect(message, contains('STDOUT:\nstdout'));
+      expect(message, contains('STDERR:\nstderr'));
+    } finally {
+      testEnv.cleanup();
+    }
+  });
+
+  test('gn.desc handles unparseable stdout', () async {
+    final TestEnvironment testEnv = TestEnvironment.withTestEngine(
+      cannedProcesses: <CannedProcess>[
+        CannedProcess(
+          (List<String> command) => command.contains('desc'),
+          stdout: 'not json',
+        ),
+      ],
+    );
+    try {
+      final Gn gn = Gn.fromEnvironment(testEnv.environment);
+      await gn.desc('out/Release', TargetPattern('//foo', 'bar'));
+      fail('Expected an exception');
+    } catch (e) {
+      final String message = '$e';
+      expect(message, contains('Failed to parse JSON'));
+      expect(message, contains('not json'));
+    } finally {
+      testEnv.cleanup();
+    }
+  });
+
+  test('gn.desc parses build targets', () async {
+    final TestEnvironment testEnv = TestEnvironment.withTestEngine(
+      cannedProcesses: <CannedProcess>[
+        CannedProcess(
+          (List<String> command) => command.contains('desc'),
+          stdout: '''
+            {
+              "//foo/bar:baz_test": {
+                "outputs": ["//out/host_debug/foo/bar/baz_test"],
+                "testonly": true,
+                "type": "executable"
+              },
+              "//foo/bar:baz_shared_library": {
+                "testonly": false,
+                "type": "shared_library"
+              },
+              "//foo/bar:baz_static_library": {
+                "testonly": false,
+                "type": "static_library"
+              }
+            }
+          ''',
+        ),
+      ],
+    );
+    try {
+      final Gn gn = Gn.fromEnvironment(testEnv.environment);
+      final List<BuildTarget> targets = await gn.desc('out/Release', TargetPattern('//foo', 'bar'));
+      expect(targets, hasLength(3));
+
+      // There should be exactly one binary test target and two library targets.
+      final ExecutableBuildTarget testTarget = targets.whereType<ExecutableBuildTarget>().single;
+      expect(testTarget, ExecutableBuildTarget(
+        label: Label('//foo/bar', 'baz_test'),
+        testOnly: true,
+        executable: 'out/host_debug/foo/bar/baz_test',
+      ));
+
+      final List<LibraryBuildTarget> libraryTargets = targets.whereType<LibraryBuildTarget>().toList();
+      expect(libraryTargets, hasLength(2));
+      expect(libraryTargets.contains(LibraryBuildTarget(
+        label: Label('//foo/bar', 'baz_shared_library'),
+        testOnly: false,
+      )), isTrue);
+      expect(libraryTargets.contains(LibraryBuildTarget(
+        label: Label('//foo/bar', 'baz_static_library'),
+        testOnly: false,
+      )), isTrue);
+    } finally {
+      testEnv.cleanup();
+    }
+  });
+}

From 2e1a25e80c51a747a5c7089a61f06382e235e0a7 Mon Sep 17 00:00:00 2001
From: Matan Lurey <matan@lurey.org>
Date: Wed, 15 May 2024 17:56:48 -0700
Subject: [PATCH 2/6] Fix building a missing output directory.

---
 tools/engine_tool/lib/src/build_utils.dart    | 30 ++++++++++++++++---
 .../lib/src/commands/build_command.dart       |  4 +++
 .../lib/src/commands/query_command.dart       |  4 +++
 .../lib/src/commands/test_command.dart        |  4 +++
 4 files changed, 38 insertions(+), 4 deletions(-)

diff --git a/tools/engine_tool/lib/src/build_utils.dart b/tools/engine_tool/lib/src/build_utils.dart
index 0674129dd368c..8436c8e9e22fa 100644
--- a/tools/engine_tool/lib/src/build_utils.dart
+++ b/tools/engine_tool/lib/src/build_utils.dart
@@ -2,7 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:io' as io;
+
 import 'package:engine_build_configs/engine_build_configs.dart';
+import 'package:path/path.dart' as p;
 
 import 'environment.dart';
 import 'label.dart';
@@ -179,13 +182,22 @@ Future<int> runBuild(
   return buildResult ? 0 : 1;
 }
 
-/// Given a [Build] object, run only its GN step.
-Future<int> runGn(
+/// Run a [build]'s GN step if the output directory is missing.
+///
+/// TODO(matanlurey): https://github.com/flutter/flutter/issues/148442.
+Future<bool> ensureBuildDir(
   Environment environment,
   Build build, {
   List<String> extraGnArgs = const <String>[],
   required bool enableRbe,
 }) async {
+  final io.Directory buildDir = io.Directory(
+    p.join(environment.engine.outDir.path, build.ninja.config),
+  );
+  if (buildDir.existsSync()) {
+    return true;
+  }
+
   final List<String> gnArgs = <String>[
     if (!enableRbe) '--no-rbe',
     ...extraGnArgs,
@@ -203,12 +215,22 @@ Future<int> runGn(
     runTests: false,
   );
 
-  final bool buildResult = await buildRunner.run((RunnerEvent event) {
+  final bool built = await buildRunner.run((RunnerEvent event) {
     switch (event) {
       case RunnerResult(ok: false):
         environment.logger.error(event);
       default:
     }
   });
-  return buildResult ? 0 : 1;
+  if (built) {
+    if (!buildDir.existsSync()) {
+      environment.logger.error(
+        'The specified build did not produce the expected output directory: '
+        '${buildDir.path}',
+      );
+      return false;
+    }
+    return true;
+  }
+  return false;
 }
diff --git a/tools/engine_tool/lib/src/commands/build_command.dart b/tools/engine_tool/lib/src/commands/build_command.dart
index 91f024732dc1c..8aa940c7cc7b6 100644
--- a/tools/engine_tool/lib/src/commands/build_command.dart
+++ b/tools/engine_tool/lib/src/commands/build_command.dart
@@ -76,6 +76,10 @@ et build //flutter/fml:fml_benchmarks  # Build a specific target in `//flutter/f
       if (useLto) '--lto' else '--no-lto',
     ];
 
+    if (!await ensureBuildDir(environment, build, enableRbe: useRbe)) {
+      return 1;
+    }
+
     // Builds only accept labels as arguments, so convert patterns to labels.
     // TODO(matanlurey): Can be optimized in cases where wildcards are not used.
     final Gn gn = Gn.fromEnvironment(environment);
diff --git a/tools/engine_tool/lib/src/commands/query_command.dart b/tools/engine_tool/lib/src/commands/query_command.dart
index 991623131aa75..37ed01031a290 100644
--- a/tools/engine_tool/lib/src/commands/query_command.dart
+++ b/tools/engine_tool/lib/src/commands/query_command.dart
@@ -195,6 +195,10 @@ et query targets //flutter/fml/...  # List all targets under `//flutter/fml`
       return 1;
     }
 
+    if (!await ensureBuildDir(environment, build, enableRbe: useRbe)) {
+      return 1;
+    }
+
     // Builds only accept labels as arguments, so convert patterns to labels.
     // TODO(matanlurey): Can be optimized in cases where wildcards are not used.
     final Gn gn = Gn.fromEnvironment(environment);
diff --git a/tools/engine_tool/lib/src/commands/test_command.dart b/tools/engine_tool/lib/src/commands/test_command.dart
index 381ceba75ceaa..a48e10efec093 100644
--- a/tools/engine_tool/lib/src/commands/test_command.dart
+++ b/tools/engine_tool/lib/src/commands/test_command.dart
@@ -68,6 +68,10 @@ et test //flutter/fml:fml_benchmarks  # Run a single test target in `//flutter/f
       return 1;
     }
 
+    if (!await ensureBuildDir(environment, build, enableRbe: useRbe)) {
+      return 1;
+    }
+
     // Builds only accept labels as arguments, so convert patterns to labels.
     final Gn gn = Gn.fromEnvironment(environment);
 

From ad5de84e3506bc13b92821a1a6f91f69bfb7eed7 Mon Sep 17 00:00:00 2001
From: Matan Lurey <matan@lurey.org>
Date: Wed, 15 May 2024 18:44:28 -0700
Subject: [PATCH 3/6] Fix tests.

---
 tools/engine_tool/lib/src/build_utils.dart    |  8 +++--
 .../engine_tool/test/build_command_test.dart  | 31 ++++++++++++-------
 tools/engine_tool/test/utils.dart             |  5 +--
 3 files changed, 28 insertions(+), 16 deletions(-)

diff --git a/tools/engine_tool/lib/src/build_utils.dart b/tools/engine_tool/lib/src/build_utils.dart
index 8436c8e9e22fa..fa9bcab51fac8 100644
--- a/tools/engine_tool/lib/src/build_utils.dart
+++ b/tools/engine_tool/lib/src/build_utils.dart
@@ -183,16 +183,18 @@ Future<int> runBuild(
 }
 
 /// Run a [build]'s GN step if the output directory is missing.
-///
-/// TODO(matanlurey): https://github.com/flutter/flutter/issues/148442.
 Future<bool> ensureBuildDir(
   Environment environment,
   Build build, {
   List<String> extraGnArgs = const <String>[],
   required bool enableRbe,
 }) async {
+  // TODO(matanlurey): https://github.com/flutter/flutter/issues/148442.
   final io.Directory buildDir = io.Directory(
-    p.join(environment.engine.outDir.path, build.ninja.config),
+    p.join(
+      environment.engine.outDir.path,
+      build.ninja.config,
+    ),
   );
   if (buildDir.existsSync()) {
     return true;
diff --git a/tools/engine_tool/test/build_command_test.dart b/tools/engine_tool/test/build_command_test.dart
index c8af8cc3fe68a..d5c10d076ea95 100644
--- a/tools/engine_tool/test/build_command_test.dart
+++ b/tools/engine_tool/test/build_command_test.dart
@@ -64,6 +64,7 @@ void main() {
   test('build command invokes gn', () async {
     final TestEnvironment testEnv = TestEnvironment.withTestEngine(
       cannedProcesses: cannedProcesses,
+      expectedOutDir: 'build_name',
     );
     try {
       final ToolCommandRunner runner = ToolCommandRunner(
@@ -86,6 +87,7 @@ void main() {
   test('build command invokes ninja', () async {
     final TestEnvironment testEnv = TestEnvironment.withTestEngine(
       cannedProcesses: cannedProcesses,
+      expectedOutDir: 'build_name',
     );
     try {
       final ToolCommandRunner runner = ToolCommandRunner(
@@ -99,7 +101,7 @@ void main() {
       ]);
       expect(result, equals(0));
       expect(testEnv.processHistory.length, greaterThanOrEqualTo(2));
-      expect(testEnv.processHistory[1].command[0], contains('ninja'));
+      expect(testEnv.processHistory[2].command[0], contains('ninja'));
     } finally {
       testEnv.cleanup();
     }
@@ -108,6 +110,7 @@ void main() {
   test('build command invokes generator', () async {
     final TestEnvironment testEnv = TestEnvironment.withTestEngine(
       cannedProcesses: cannedProcesses,
+      expectedOutDir: 'build_name',
     );
     try {
       final ToolCommandRunner runner = ToolCommandRunner(
@@ -122,7 +125,7 @@ void main() {
       expect(result, equals(0));
       expect(testEnv.processHistory.length, greaterThanOrEqualTo(3));
       expect(
-        testEnv.processHistory[2].command,
+        testEnv.processHistory[3].command,
         containsStringsInOrder(<String>['python3', 'gen/script.py']),
       );
     } finally {
@@ -133,6 +136,7 @@ void main() {
   test('build command does not invoke tests', () async {
     final TestEnvironment testEnv = TestEnvironment.withTestEngine(
       cannedProcesses: cannedProcesses,
+      expectedOutDir: 'build_name',
     );
     try {
       final ToolCommandRunner runner = ToolCommandRunner(
@@ -155,6 +159,7 @@ void main() {
     final TestEnvironment testEnv = TestEnvironment.withTestEngine(
       withRbe: true,
       cannedProcesses: cannedProcesses,
+      expectedOutDir: 'android_debug_rbe_arm64',
     );
     try {
       final ToolCommandRunner runner = ToolCommandRunner(
@@ -167,10 +172,10 @@ void main() {
         'ci/android_debug_rbe_arm64',
       ]);
       expect(result, equals(0));
-      expect(testEnv.processHistory[0].command[0],
-          contains(path.join('tools', 'gn')));
-      expect(testEnv.processHistory[0].command[2], equals('--rbe'));
       expect(testEnv.processHistory[1].command[0],
+          contains(path.join('tools', 'gn')));
+      expect(testEnv.processHistory[1].command[2], equals('--rbe'));
+      expect(testEnv.processHistory[2].command[0],
           contains(path.join('reclient', 'bootstrap')));
     } finally {
       testEnv.cleanup();
@@ -208,6 +213,7 @@ void main() {
     final TestEnvironment testEnv = TestEnvironment.withTestEngine(
       withRbe: true,
       cannedProcesses: cannedProcesses,
+      expectedOutDir: 'android_debug_rbe_arm64',
     );
     try {
       final ToolCommandRunner runner = ToolCommandRunner(
@@ -225,7 +231,7 @@ void main() {
           contains(path.join('tools', 'gn')));
       expect(testEnv.processHistory[0].command,
           doesNotContainAny(<String>['--rbe']));
-      expect(testEnv.processHistory[1].command[0],
+      expect(testEnv.processHistory[2].command[0],
           contains(path.join('ninja', 'ninja')));
     } finally {
       testEnv.cleanup();
@@ -236,6 +242,7 @@ void main() {
       () async {
     final TestEnvironment testEnv = TestEnvironment.withTestEngine(
       cannedProcesses: cannedProcesses,
+      expectedOutDir: 'android_debug_rbe_arm64',
     );
     try {
       final ToolCommandRunner runner = ToolCommandRunner(
@@ -252,7 +259,7 @@ void main() {
           contains(path.join('tools', 'gn')));
       expect(testEnv.processHistory[0].command,
           doesNotContainAny(<String>['--rbe']));
-      expect(testEnv.processHistory[1].command[0],
+      expect(testEnv.processHistory[2].command[0],
           contains(path.join('ninja', 'ninja')));
     } finally {
       testEnv.cleanup();
@@ -309,6 +316,7 @@ void main() {
     };
     final TestEnvironment testEnv = TestEnvironment.withTestEngine(
       cannedProcesses: cannedProcesses,
+      expectedOutDir: 'local_host_debug',
     );
     try {
       final ToolCommandRunner runner = ToolCommandRunner(
@@ -321,10 +329,10 @@ void main() {
         'host_debug',
       ]);
       expect(result, equals(0));
-      expect(testEnv.processHistory[1].command[0],
+      expect(testEnv.processHistory[2].command[0],
           contains(path.join('ninja', 'ninja')));
       expect(
-          testEnv.processHistory[1].command[2], contains('local_host_debug'));
+          testEnv.processHistory[2].command[2], contains('local_host_debug'));
     } finally {
       testEnv.cleanup();
     }
@@ -341,6 +349,7 @@ void main() {
     };
     final TestEnvironment testEnv = TestEnvironment.withTestEngine(
       cannedProcesses: cannedProcesses,
+      expectedOutDir: 'ci/host_debug',
     );
     final Environment env = testEnv.environment;
     try {
@@ -354,9 +363,9 @@ void main() {
         'ci/host_debug',
       ]);
       expect(result, equals(0));
-      expect(testEnv.processHistory[1].command[0],
+      expect(testEnv.processHistory[2].command[0],
           contains(path.join('ninja', 'ninja')));
-      expect(testEnv.processHistory[1].command[2], contains('ci/host_debug'));
+      expect(testEnv.processHistory[2].command[2], contains('ci/host_debug'));
     } finally {
       testEnv.cleanup();
     }
diff --git a/tools/engine_tool/test/utils.dart b/tools/engine_tool/test/utils.dart
index b00e009d546a0..a21954c6f8c80 100644
--- a/tools/engine_tool/test/utils.dart
+++ b/tools/engine_tool/test/utils.dart
@@ -89,6 +89,7 @@ class TestEnvironment {
     ffi.Abi abi = ffi.Abi.linuxX64,
     List<CannedProcess> cannedProcesses = const <CannedProcess>[],
     bool verbose = false,
+    String expectedOutDir = 'host_debug',
   }) {
     final io.Directory rootDir = io.Directory.systemTemp.createTempSync('et');
     final TestEngine engine = TestEngine.createTemp(rootDir: rootDir);
@@ -100,12 +101,12 @@ class TestEnvironment {
         'rbe',
       )).createSync(recursive: true);
     }
-    // When GN runs, always try to create out/host_debug.
+    // When GN runs, always try to create {expectedOutDir}.
     final CannedProcess cannedGn = CannedProcess((List<String> command) {
       if (command[0].endsWith('/gn') && !command.contains('desc')) {
         io.Directory(path.join(
           engine.outDir.path,
-          'host_debug',
+          expectedOutDir,
         )).createSync(recursive: true);
         return true;
       }

From 0a733f3a3cc01faa73f4d09485a6e2075933cd27 Mon Sep 17 00:00:00 2001
From: Matan Lurey <matan@lurey.org>
Date: Wed, 15 May 2024 20:05:37 -0700
Subject: [PATCH 4/6] Address feedback.

---
 tools/engine_tool/lib/src/build_utils.dart    | 37 ++++++++++++-------
 .../lib/src/commands/build_command.dart       |  5 ++-
 .../engine_tool/test/build_command_test.dart  | 22 +++++------
 3 files changed, 38 insertions(+), 26 deletions(-)

diff --git a/tools/engine_tool/lib/src/build_utils.dart b/tools/engine_tool/lib/src/build_utils.dart
index fa9bcab51fac8..6c29fe15b486b 100644
--- a/tools/engine_tool/lib/src/build_utils.dart
+++ b/tools/engine_tool/lib/src/build_utils.dart
@@ -187,7 +187,7 @@ Future<bool> ensureBuildDir(
   Environment environment,
   Build build, {
   List<String> extraGnArgs = const <String>[],
-  required bool enableRbe,
+  required bool enableRbe,  
 }) async {
   // TODO(matanlurey): https://github.com/flutter/flutter/issues/148442.
   final io.Directory buildDir = io.Directory(
@@ -200,6 +200,28 @@ Future<bool> ensureBuildDir(
     return true;
   }
 
+  final bool built = await _runGn(
+    environment,
+    build,
+    extraGnArgs: extraGnArgs,
+    enableRbe: enableRbe,
+  );
+  if (built && !buildDir.existsSync()) {
+    environment.logger.error(
+      'The specified build did not produce the expected output directory: '
+      '${buildDir.path}',
+    );
+    return false;
+  }
+  return built;  
+}
+
+Future<bool> _runGn(
+  Environment environment,
+  Build build, {
+  List<String> extraGnArgs = const <String>[],
+  required bool enableRbe,
+}) async {
   final List<String> gnArgs = <String>[
     if (!enableRbe) '--no-rbe',
     ...extraGnArgs,
@@ -217,22 +239,11 @@ Future<bool> ensureBuildDir(
     runTests: false,
   );
 
-  final bool built = await buildRunner.run((RunnerEvent event) {
+  return buildRunner.run((RunnerEvent event) {
     switch (event) {
       case RunnerResult(ok: false):
         environment.logger.error(event);
       default:
     }
   });
-  if (built) {
-    if (!buildDir.existsSync()) {
-      environment.logger.error(
-        'The specified build did not produce the expected output directory: '
-        '${buildDir.path}',
-      );
-      return false;
-    }
-    return true;
-  }
-  return false;
 }
diff --git a/tools/engine_tool/lib/src/commands/build_command.dart b/tools/engine_tool/lib/src/commands/build_command.dart
index 8aa940c7cc7b6..9dc0c42c4ed3a 100644
--- a/tools/engine_tool/lib/src/commands/build_command.dart
+++ b/tools/engine_tool/lib/src/commands/build_command.dart
@@ -76,7 +76,8 @@ et build //flutter/fml:fml_benchmarks  # Build a specific target in `//flutter/f
       if (useLto) '--lto' else '--no-lto',
     ];
 
-    if (!await ensureBuildDir(environment, build, enableRbe: useRbe)) {
+    final List<String> commandLineTargets = argResults!.rest;
+    if (commandLineTargets.isNotEmpty && !await ensureBuildDir(environment, build, enableRbe: useRbe)) {
       return 1;
     }
 
@@ -84,7 +85,7 @@ et build //flutter/fml:fml_benchmarks  # Build a specific target in `//flutter/f
     // TODO(matanlurey): Can be optimized in cases where wildcards are not used.
     final Gn gn = Gn.fromEnvironment(environment);
     final Set<Label> allTargets = <Label>{};
-    for (final String pattern in argResults!.rest) {
+    for (final String pattern in commandLineTargets) {
       final TargetPattern target = TargetPattern.parse(pattern);
       final List<BuildTarget> targets = await gn.desc(
         'out/${build.ninja.config}',
diff --git a/tools/engine_tool/test/build_command_test.dart b/tools/engine_tool/test/build_command_test.dart
index d5c10d076ea95..bd2d2e7c5e1a1 100644
--- a/tools/engine_tool/test/build_command_test.dart
+++ b/tools/engine_tool/test/build_command_test.dart
@@ -101,7 +101,7 @@ void main() {
       ]);
       expect(result, equals(0));
       expect(testEnv.processHistory.length, greaterThanOrEqualTo(2));
-      expect(testEnv.processHistory[2].command[0], contains('ninja'));
+      expect(testEnv.processHistory[1].command[0], contains('ninja'));
     } finally {
       testEnv.cleanup();
     }
@@ -125,7 +125,7 @@ void main() {
       expect(result, equals(0));
       expect(testEnv.processHistory.length, greaterThanOrEqualTo(3));
       expect(
-        testEnv.processHistory[3].command,
+        testEnv.processHistory[2].command,
         containsStringsInOrder(<String>['python3', 'gen/script.py']),
       );
     } finally {
@@ -172,10 +172,10 @@ void main() {
         'ci/android_debug_rbe_arm64',
       ]);
       expect(result, equals(0));
-      expect(testEnv.processHistory[1].command[0],
+      expect(testEnv.processHistory[0].command[0],
           contains(path.join('tools', 'gn')));
-      expect(testEnv.processHistory[1].command[2], equals('--rbe'));
-      expect(testEnv.processHistory[2].command[0],
+      expect(testEnv.processHistory[0].command[2], equals('--rbe'));
+      expect(testEnv.processHistory[1].command[0],
           contains(path.join('reclient', 'bootstrap')));
     } finally {
       testEnv.cleanup();
@@ -231,7 +231,7 @@ void main() {
           contains(path.join('tools', 'gn')));
       expect(testEnv.processHistory[0].command,
           doesNotContainAny(<String>['--rbe']));
-      expect(testEnv.processHistory[2].command[0],
+      expect(testEnv.processHistory[1].command[0],
           contains(path.join('ninja', 'ninja')));
     } finally {
       testEnv.cleanup();
@@ -259,7 +259,7 @@ void main() {
           contains(path.join('tools', 'gn')));
       expect(testEnv.processHistory[0].command,
           doesNotContainAny(<String>['--rbe']));
-      expect(testEnv.processHistory[2].command[0],
+      expect(testEnv.processHistory[1].command[0],
           contains(path.join('ninja', 'ninja')));
     } finally {
       testEnv.cleanup();
@@ -329,10 +329,10 @@ void main() {
         'host_debug',
       ]);
       expect(result, equals(0));
-      expect(testEnv.processHistory[2].command[0],
+      expect(testEnv.processHistory[1].command[0],
           contains(path.join('ninja', 'ninja')));
       expect(
-          testEnv.processHistory[2].command[2], contains('local_host_debug'));
+          testEnv.processHistory[1].command[2], contains('local_host_debug'));
     } finally {
       testEnv.cleanup();
     }
@@ -363,9 +363,9 @@ void main() {
         'ci/host_debug',
       ]);
       expect(result, equals(0));
-      expect(testEnv.processHistory[2].command[0],
+      expect(testEnv.processHistory[1].command[0],
           contains(path.join('ninja', 'ninja')));
-      expect(testEnv.processHistory[2].command[2], contains('ci/host_debug'));
+      expect(testEnv.processHistory[1].command[2], contains('ci/host_debug'));
     } finally {
       testEnv.cleanup();
     }

From 980ee958ec6a1e652db5edf666cfa7d7395cd802 Mon Sep 17 00:00:00 2001
From: Matan Lurey <matan@lurey.org>
Date: Wed, 15 May 2024 20:07:42 -0700
Subject: [PATCH 5/6] ++

---
 tools/engine_tool/lib/src/build_utils.dart | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/engine_tool/lib/src/build_utils.dart b/tools/engine_tool/lib/src/build_utils.dart
index 6c29fe15b486b..0f5a537e82f80 100644
--- a/tools/engine_tool/lib/src/build_utils.dart
+++ b/tools/engine_tool/lib/src/build_utils.dart
@@ -187,7 +187,7 @@ Future<bool> ensureBuildDir(
   Environment environment,
   Build build, {
   List<String> extraGnArgs = const <String>[],
-  required bool enableRbe,  
+  required bool enableRbe,
 }) async {
   // TODO(matanlurey): https://github.com/flutter/flutter/issues/148442.
   final io.Directory buildDir = io.Directory(
@@ -213,7 +213,7 @@ Future<bool> ensureBuildDir(
     );
     return false;
   }
-  return built;  
+  return built;
 }
 
 Future<bool> _runGn(

From d664dce577578ad7b8d9b59552af687d494007f2 Mon Sep 17 00:00:00 2001
From: Matan Lurey <matan@lurey.org>
Date: Wed, 15 May 2024 20:17:55 -0700
Subject: [PATCH 6/6] Revert test changes.

---
 tools/engine_tool/test/build_command_test.dart | 9 ---------
 tools/engine_tool/test/utils.dart              | 5 ++---
 2 files changed, 2 insertions(+), 12 deletions(-)

diff --git a/tools/engine_tool/test/build_command_test.dart b/tools/engine_tool/test/build_command_test.dart
index bd2d2e7c5e1a1..c8af8cc3fe68a 100644
--- a/tools/engine_tool/test/build_command_test.dart
+++ b/tools/engine_tool/test/build_command_test.dart
@@ -64,7 +64,6 @@ void main() {
   test('build command invokes gn', () async {
     final TestEnvironment testEnv = TestEnvironment.withTestEngine(
       cannedProcesses: cannedProcesses,
-      expectedOutDir: 'build_name',
     );
     try {
       final ToolCommandRunner runner = ToolCommandRunner(
@@ -87,7 +86,6 @@ void main() {
   test('build command invokes ninja', () async {
     final TestEnvironment testEnv = TestEnvironment.withTestEngine(
       cannedProcesses: cannedProcesses,
-      expectedOutDir: 'build_name',
     );
     try {
       final ToolCommandRunner runner = ToolCommandRunner(
@@ -110,7 +108,6 @@ void main() {
   test('build command invokes generator', () async {
     final TestEnvironment testEnv = TestEnvironment.withTestEngine(
       cannedProcesses: cannedProcesses,
-      expectedOutDir: 'build_name',
     );
     try {
       final ToolCommandRunner runner = ToolCommandRunner(
@@ -136,7 +133,6 @@ void main() {
   test('build command does not invoke tests', () async {
     final TestEnvironment testEnv = TestEnvironment.withTestEngine(
       cannedProcesses: cannedProcesses,
-      expectedOutDir: 'build_name',
     );
     try {
       final ToolCommandRunner runner = ToolCommandRunner(
@@ -159,7 +155,6 @@ void main() {
     final TestEnvironment testEnv = TestEnvironment.withTestEngine(
       withRbe: true,
       cannedProcesses: cannedProcesses,
-      expectedOutDir: 'android_debug_rbe_arm64',
     );
     try {
       final ToolCommandRunner runner = ToolCommandRunner(
@@ -213,7 +208,6 @@ void main() {
     final TestEnvironment testEnv = TestEnvironment.withTestEngine(
       withRbe: true,
       cannedProcesses: cannedProcesses,
-      expectedOutDir: 'android_debug_rbe_arm64',
     );
     try {
       final ToolCommandRunner runner = ToolCommandRunner(
@@ -242,7 +236,6 @@ void main() {
       () async {
     final TestEnvironment testEnv = TestEnvironment.withTestEngine(
       cannedProcesses: cannedProcesses,
-      expectedOutDir: 'android_debug_rbe_arm64',
     );
     try {
       final ToolCommandRunner runner = ToolCommandRunner(
@@ -316,7 +309,6 @@ void main() {
     };
     final TestEnvironment testEnv = TestEnvironment.withTestEngine(
       cannedProcesses: cannedProcesses,
-      expectedOutDir: 'local_host_debug',
     );
     try {
       final ToolCommandRunner runner = ToolCommandRunner(
@@ -349,7 +341,6 @@ void main() {
     };
     final TestEnvironment testEnv = TestEnvironment.withTestEngine(
       cannedProcesses: cannedProcesses,
-      expectedOutDir: 'ci/host_debug',
     );
     final Environment env = testEnv.environment;
     try {
diff --git a/tools/engine_tool/test/utils.dart b/tools/engine_tool/test/utils.dart
index a21954c6f8c80..b00e009d546a0 100644
--- a/tools/engine_tool/test/utils.dart
+++ b/tools/engine_tool/test/utils.dart
@@ -89,7 +89,6 @@ class TestEnvironment {
     ffi.Abi abi = ffi.Abi.linuxX64,
     List<CannedProcess> cannedProcesses = const <CannedProcess>[],
     bool verbose = false,
-    String expectedOutDir = 'host_debug',
   }) {
     final io.Directory rootDir = io.Directory.systemTemp.createTempSync('et');
     final TestEngine engine = TestEngine.createTemp(rootDir: rootDir);
@@ -101,12 +100,12 @@ class TestEnvironment {
         'rbe',
       )).createSync(recursive: true);
     }
-    // When GN runs, always try to create {expectedOutDir}.
+    // When GN runs, always try to create out/host_debug.
     final CannedProcess cannedGn = CannedProcess((List<String> command) {
       if (command[0].endsWith('/gn') && !command.contains('desc')) {
         io.Directory(path.join(
           engine.outDir.path,
-          expectedOutDir,
+          'host_debug',
         )).createSync(recursive: true);
         return true;
       }