flutter · jonahwilliams · Oct 6, 2020 · jonahwilliams · Oct 6, 2020 · jonahwilliams
diff --git a/packages/flutter_tools/lib/src/base/file_system.dart b/packages/flutter_tools/lib/src/base/file_system.dart
@@ -17,6 +17,40 @@ import 'signals.dart';
 // the tool is killed by a signal.
 export 'package:file/file.dart';

+extension FileUtils on File {
diff --git a/packages/flutter_tools/lib/src/base/file_system.dart b/packages/flutter_tools/lib/src/base/file_system.dart
@@ -17,6 +17,40 @@ import 'signals.dart';
 // the tool is killed by a signal.
 export 'package:file/file.dart';

+extension FileUtils on File {
diff --git a/packages/flutter_tools/test/general.shard/base/file_system_test.dart b/packages/flutter_tools/test/general.shard/base/file_system_test.dart
@@ -57,6 +58,44 @@ void main() {
    });
  });

+  testWithoutContext('deleteIfExists does not delete if file does not exist', () {
diff --git a/packages/flutter_tools/lib/src/base/file_system.dart b/packages/flutter_tools/lib/src/base/file_system.dart
+    }
+    try {
+      deleteSync(recursive: recursive);
+    } on FileSystemException catch (err) {
diff --git a/packages/flutter_tools/lib/src/base/file_system.dart b/packages/flutter_tools/lib/src/base/file_system.dart
+        rethrow;
+      }
+      if (existsSync()) {
+        throwToolExit(
diff --git a/packages/flutter_tools/lib/src/base/error_handling_io.dart b/packages/flutter_tools/lib/src/base/error_handling_io.dart
+      // been deleted by a different program while the tool was running.
+      // if it still exists, the file likely exists on a read-only volume.
+      // This error code is the same across linux, windows, and macOS.
+      const int kSystemCannotFindFile = 2;
diff --git a/packages/flutter_tools/lib/src/base/error_handling_io.dart b/packages/flutter_tools/lib/src/base/error_handling_io.dart
+  /// This method should be prefered to checking if it exists and
+  /// then deleting, because it handles the edge case where the file is
+  /// deleted by a different program between the two calls.
+  static bool deleteFileIfExists(File file, {bool recursive = false}) {
diff --git a/packages/flutter_tools/test/commands.shard/permeable/analyze_once_test.dart b/packages/flutter_tools/test/commands.shard/permeable/analyze_once_test.dart
@@ -241,9 +242,7 @@ flutter_project:lib/
        toolExit: true,
      );
    } finally {
-      if (optionsFile.existsSync()) {
diff --git a/packages/flutter_tools/test/commands.shard/permeable/analyze_once_test.dart b/packages/flutter_tools/test/commands.shard/permeable/analyze_once_test.dart
@@ -241,9 +242,7 @@ flutter_project:lib/
        toolExit: true,
      );
    } finally {
-      if (optionsFile.existsSync()) {