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Support creating temporary directories on POSIX (#220)
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‎pkgs/io_file/lib/src/file_system.dart

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@@ -54,6 +54,37 @@ base class FileSystem {
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throw UnsupportedError('createDirectory');
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}
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/// Creates a temporary directory and returns its path.
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///
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/// If `parent` is specified, then the temporary directory is created inside
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/// that directory. If `parent` is not specified, then the temporary directory
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/// will be created inside the directory found in [temporaryDirectory]. If
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/// `parent` is the empty string, then the temporary directory will be created
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/// in the current working directory. If the parent directory does not exist,
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/// then `PathExistsException` is thrown.
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///
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/// The temporary directory name is constructed by combining the parent
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/// directory path, `prefix` (or the empty string if it is not provided), and
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/// some random characters to make the temporary directory name unique. Some
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/// characters in `prefix` may be removed or replaced. If `prefix` contains
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/// any directory navigation characters then they will be used. For example,
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/// a `prefix` of `'../foo'` will create a sibling directory to the parent
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/// directory.
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///
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/// TODO(brianquinlan): Write to a file in the created temporary directory
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/// when that is supported.
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///
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/// ```dart
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/// import 'package:io_file/io_file.dart';
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///
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/// void main() {
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/// fileSystem.createTemporaryDirectory(prefix: 'myproject');
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/// }
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/// ```
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String createTemporaryDirectory({String? parent, String? prefix}) {
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throw UnsupportedError('createTemporaryDirectory');
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}
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/// Deletes the directory at the given path.
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///
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/// If `path` is a directory but the directory is not empty, then
@@ -95,6 +126,18 @@ base class FileSystem {
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throw UnsupportedError('readAsBytes');
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}
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/// The directory path used to store temporary files.
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///
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/// On Android, Linux, macOS and iOS, the path is taken from:
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/// 1. the TMPDIR environment variable if set
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/// 2. the TMP environment variable if set
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/// 3. '/data/local/tmp' on Android, '/tmp' elsewhere
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///
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/// TODO(brianquinlan): Add the Windows strategy here.
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String get temporaryDirectory {
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throw UnsupportedError('temporaryDirectory');
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}
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/// Write the given bytes to a file.
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///
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/// If `path` is a broken symlink and `mode` is [WriteMode.failExisting]:

‎pkgs/io_file/lib/src/vm_posix_file_system.dart

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@@ -8,6 +8,7 @@ import 'dart:math';
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import 'dart:typed_data';
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import 'package:ffi/ffi.dart' as ffi;
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import 'package:path/path.dart' as p;
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import 'package:stdlibc/stdlibc.dart' as stdlibc;
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import 'file_system.dart';
@@ -85,6 +86,19 @@ base class PosixFileSystem extends FileSystem {
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}
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}
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@override
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String createTemporaryDirectory({String? parent, String? prefix}) {
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final directory = parent ?? temporaryDirectory;
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final template = p.join(directory, '${prefix ?? ''}XXXXXX');
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final path = stdlibc.mkdtemp(template);
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if (path == null) {
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final errno = stdlibc.errno;
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throw _getError(errno, 'mkdtemp failed', template);
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}
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return path;
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}
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@override
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void removeDirectory(String path) {
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if (stdlibc.unlinkat(stdlibc.AT_FDCWD, path, stdlibc.AT_REMOVEDIR) == -1) {
@@ -182,6 +196,13 @@ base class PosixFileSystem extends FileSystem {
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}
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}
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@override
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String get temporaryDirectory => p.canonicalize(
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stdlibc.getenv('TMPDIR') ??
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stdlibc.getenv('TMP') ??
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(io.Platform.isAndroid ? '/data/local/tmp' : '/tmp'),
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);
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@override
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void writeAsBytes(
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String path,

‎pkgs/io_file/pubspec.yaml

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@@ -9,6 +9,7 @@ environment:
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dependencies:
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ffi: ^2.1.4
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path: ^1.9.1
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stdlibc:
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git:
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# Change this to a released version.
@@ -19,5 +20,6 @@ dev_dependencies:
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args: ^2.7.0
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benchmark_harness: ^2.3.1
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dart_flutter_team_lints: ^3.4.0
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dartdoc_test: ^0.1.0
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test: ^1.24.0
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uuid: ^4.5.1

‎pkgs/io_file/test/create_temporary_directory_test.dart

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@@ -0,0 +1,167 @@
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// Copyright (c) 2025, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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@TestOn('posix')
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library;
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import 'dart:io';
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import 'package:io_file/io_file.dart';
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import 'package:path/path.dart' as p;
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import 'package:stdlibc/stdlibc.dart' as stdlibc;
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import 'package:test/test.dart';
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import 'test_utils.dart';
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void main() {
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group('createTemporaryDirectory', () {
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late String tmp;
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setUp(() => tmp = createTemp('createTemporaryDirectory'));
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tearDown(() => deleteTemp(tmp));
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//TODO(brianquinlan): test with a very long path.
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test('no arguments', () {
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final tmp1 = fileSystem.createTemporaryDirectory();
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addTearDown(() => Directory(tmp1).deleteSync());
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final tmp2 = fileSystem.createTemporaryDirectory();
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addTearDown(() => Directory(tmp2).deleteSync());
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expect(fileSystem.same(tmp1, tmp2), isFalse);
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expect(Directory(tmp1).existsSync(), isTrue);
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expect(Directory(tmp2).existsSync(), isTrue);
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});
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test('prefix', () {
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final tmp1 = fileSystem.createTemporaryDirectory(prefix: 'myprefix');
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addTearDown(() => Directory(tmp1).deleteSync());
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final tmp2 = fileSystem.createTemporaryDirectory(prefix: 'myprefix');
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addTearDown(() => Directory(tmp2).deleteSync());
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expect(tmp1, contains('myprefix'));
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expect(tmp2, contains('myprefix'));
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expect(fileSystem.same(tmp1, tmp2), isFalse);
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expect(Directory(tmp1).existsSync(), isTrue);
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expect(Directory(tmp2).existsSync(), isTrue);
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});
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test('prefix is empty string', () {
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final tmp1 = fileSystem.createTemporaryDirectory(prefix: '');
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addTearDown(() => Directory(tmp1).deleteSync());
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final tmp2 = fileSystem.createTemporaryDirectory(prefix: '');
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addTearDown(() => Directory(tmp2).deleteSync());
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expect(fileSystem.same(tmp1, tmp2), isFalse);
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expect(Directory(tmp1).existsSync(), isTrue);
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expect(Directory(tmp2).existsSync(), isTrue);
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});
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test('prefix contains XXXXXX', () {
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final tmp1 = fileSystem.createTemporaryDirectory(
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prefix: 'myprefix-XXXXXX',
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);
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addTearDown(() => Directory(tmp1).deleteSync());
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final tmp2 = fileSystem.createTemporaryDirectory(
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prefix: 'myprefix-XXXXXX',
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);
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addTearDown(() => Directory(tmp2).deleteSync());
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expect(tmp1, contains('myprefix-'));
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expect(tmp2, contains('myprefix-'));
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expect(fileSystem.same(tmp1, tmp2), isFalse);
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expect(Directory(tmp1).existsSync(), isTrue);
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expect(Directory(tmp2).existsSync(), isTrue);
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});
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test('parent', () {
80+
final tmp1 = fileSystem.createTemporaryDirectory(parent: tmp);
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final tmp2 = fileSystem.createTemporaryDirectory(parent: tmp);
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expect(tmp1, startsWith(tmp));
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expect(tmp2, startsWith(tmp));
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expect(fileSystem.same(tmp1, tmp2), isFalse);
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expect(Directory(tmp1).existsSync(), isTrue);
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expect(Directory(tmp2).existsSync(), isTrue);
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});
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test('parent is empty string', () {
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final tmp1 = fileSystem.createTemporaryDirectory(parent: '');
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addTearDown(() => Directory(tmp1).deleteSync());
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final tmp2 = fileSystem.createTemporaryDirectory(parent: '');
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addTearDown(() => Directory(tmp2).deleteSync());
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expect(p.isRelative(tmp1), isTrue);
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expect(p.isRelative(tmp2), isTrue);
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expect(fileSystem.same(tmp1, tmp2), isFalse);
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expect(Directory(tmp1).existsSync(), isTrue);
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expect(Directory(tmp2).existsSync(), isTrue);
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});
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test('parent does not exist', () {
104+
expect(
105+
() => fileSystem.createTemporaryDirectory(parent: '/foo/bar/baz'),
106+
throwsA(
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isA<PathNotFoundException>().having(
108+
(e) => e.osError?.errorCode,
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'errorCode',
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stdlibc.ENOENT,
111+
),
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),
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);
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});
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test('prefix is absolute path inside of parent', () {
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final subdir1 = '$tmp/dir1';
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Directory(subdir1).createSync();
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final tmp1 = fileSystem.createTemporaryDirectory(
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parent: subdir1,
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prefix: '$subdir1/file',
123+
);
124+
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expect(tmp1, startsWith(subdir1));
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});
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test('prefix is absolute path outside of parent', () {
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final subdir1 = '$tmp/dir1';
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final subdir2 = '$tmp/dir2';
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Directory(subdir1).createSync();
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Directory(subdir2).createSync();
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final tmp1 = fileSystem.createTemporaryDirectory(
135+
parent: subdir1,
136+
prefix: '$subdir2/file',
137+
);
138+
139+
expect(tmp1, startsWith(subdir2));
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});
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test('prefix is non-existant path inside temp directory', () {
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expect(
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() => fileSystem.createTemporaryDirectory(prefix: 'subdir/file'),
145+
throwsA(
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isA<PathNotFoundException>().having(
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(e) => e.osError?.errorCode,
148+
'errorCode',
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stdlibc.ENOENT,
150+
),
151+
),
152+
);
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});
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155+
test('prefix is existant path inside temp directory', () {
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final subdir1 = '$tmp/dir1';
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Directory(subdir1).createSync();
158+
159+
final tmp1 = fileSystem.createTemporaryDirectory(
160+
parent: tmp,
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prefix: 'dir1/file',
162+
);
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expect(tmp1, startsWith(subdir1));
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expect(Directory(tmp1).existsSync(), isTrue);
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});
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});
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}

‎pkgs/io_file/test/temporary_directory_test.dart

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@@ -0,0 +1,19 @@
1+
// Copyright (c) 2025, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
3+
// BSD-style license that can be found in the LICENSE file.
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@TestOn('posix')
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library;
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8+
import 'package:io_file/io_file.dart';
9+
import 'package:path/path.dart' as p;
10+
import 'package:test/test.dart';
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12+
void main() {
13+
group('temporaryDirectory', () {
14+
test('success', () {
15+
final tmp = fileSystem.temporaryDirectory;
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expect(p.isAbsolute(tmp), isTrue);
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});
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});
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}

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