Do not lower-case paths during canonicalization. (#9571)

* Do not lower-case paths during canonicalization.

This breaks hot reload on some platfroms with case insensitive file systems.

* Add unit tests

packages/flutter_tools/lib/src/base/file_system.dart

@@ -134,3 +134,11 @@ Directory getReplaySource(String dirname, String basename) {
     throwToolExit('Invalid replay-from location: $dirname ("$basename" does not exist)');
   return dir;
 }
+
+/// Canonicalizes [path].
+///
+/// This function implements the behaviour of `canonicalize` from
+/// `package:path`. However, unlike the original, it does not change the ASCII
+/// case of the path. Changing the case can break hot reload in some situations,
+/// for an example see: https://github.com/flutter/flutter/issues/9539.
+String canonicalizePath(String path) => fs.path.normalize(fs.path.absolute(path));

packages/flutter_tools/lib/src/dart/dependencies.dart

@@ -9,9 +9,9 @@ import '../dart/package_map.dart';
 
 class DartDependencySetBuilder {
   DartDependencySetBuilder(String mainScriptPath, String packagesFilePath) :
-    _mainScriptPath = fs.path.canonicalize(mainScriptPath),
+    _mainScriptPath = canonicalizePath(mainScriptPath),
     _mainScriptUri = fs.path.toUri(mainScriptPath),
-    _packagesFilePath = fs.path.canonicalize(packagesFilePath);
+    _packagesFilePath = canonicalizePath(packagesFilePath);
 
   final String _mainScriptPath;
   final String _packagesFilePath;
@@ -48,7 +48,7 @@ class DartDependencySetBuilder {
           }
           resolvedUri = newResolvedUri;
         }
-        final String path = fs.path.canonicalize(resolvedUri.toFilePath());
+        final String path = canonicalizePath(resolvedUri.toFilePath());
         if (!dependencies.contains(path)) {
           if (!fs.isFileSync(path)) {
             throw new DartDependencyException(

packages/flutter_tools/lib/src/devfs.dart

@@ -499,7 +499,6 @@ class DevFS {
                    String relativePath,
                    Uri directoryUriOnDevice, {
                    bool ignoreDotFiles: true,
-                   Set<String> fileFilter
                    }) {
     if (file is Directory) {
       // Skip non-files.
@@ -510,13 +509,6 @@ class DevFS {
       // Skip dot files.
       return true;
     }
-    if (fileFilter != null) {
-      final String canonicalizeFilePath = fs.path.canonicalize(file.absolute.path);
-      if ((fileFilter != null) && !fileFilter.contains(canonicalizeFilePath)) {
-        // Skip files that are not included in the filter.
-        return true;
-      }
-    }
     return false;
   }
 
@@ -542,8 +534,7 @@ class DevFS {
     directoryUriOnDevice =
         _directoryUriOnDevice(directoryUriOnDevice, directory);
     try {
-      final String absoluteDirectoryPath =
-          fs.path.canonicalize(fs.path.absolute(directory.path));
+      final String absoluteDirectoryPath = canonicalizePath(directory.path);
       // For each file in the file filter.
       for (String filePath in fileFilter) {
         if (!filePath.startsWith(absoluteDirectoryPath)) {
@@ -600,7 +591,7 @@ class DevFS {
         }
         final String relativePath =
           fs.path.relative(file.path, from: directory.path);
-        if (_shouldSkip(file, relativePath, directoryUriOnDevice, ignoreDotFiles: ignoreDotFiles, fileFilter: fileFilter)) {
+        if (_shouldSkip(file, relativePath, directoryUriOnDevice, ignoreDotFiles: ignoreDotFiles)) {
           continue;
         }
         final Uri deviceUri = directoryUriOnDevice.resolveUri(fs.path.toUri(relativePath));

packages/flutter_tools/test/dart_dependencies_test.dart

@@ -27,8 +27,8 @@ void main()  {
       final DartDependencySetBuilder builder =
           new DartDependencySetBuilder(mainPath, packagesPath);
       final Set<String> dependencies = builder.build();
-      expect(dependencies.contains(fs.path.canonicalize(mainPath)), isTrue);
-      expect(dependencies.contains(fs.path.canonicalize(fs.path.join(testPath, 'foo.dart'))), isTrue);
+      expect(dependencies.contains(canonicalizePath(mainPath)), isTrue);
+      expect(dependencies.contains(canonicalizePath(fs.path.join(testPath, 'foo.dart'))), isTrue);
     });
 
     testUsingContext('syntax_error', () {
@@ -73,5 +73,14 @@ void main()  {
         expect(error.toString(), contains('pubspec.yaml'));
       }
     });
+
+    testUsingContext('does not change ASCI casing of path', () {
+      final String testPath = fs.path.join(dataPath, 'asci_casing');
+      final String mainPath = fs.path.join(testPath, 'main.dart');
+      final String packagesPath = fs.path.join(testPath, '.packages');
+      final DartDependencySetBuilder builder = new DartDependencySetBuilder(mainPath, packagesPath);
+      final Set<String> deps = builder.build();
+      expect(deps, contains(endsWith('This_Import_Has_fuNNy_casING.dart')));
+    });
   });
 }

packages/flutter_tools/test/data/dart_dependencies_test/asci_casing/.analysis_options

+analyzer:
+  exclude:
+    - '**'

packages/flutter_tools/test/data/dart_dependencies_test/asci_casing/.packages

+self:lib/

packages/flutter_tools/test/data/dart_dependencies_test/asci_casing/This_Import_Has_fuNNy_casING.dart

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+String dummy = 'Hello';

packages/flutter_tools/test/data/dart_dependencies_test/asci_casing/main.dart

+// Copyright 2017 The Chromium 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 'This_Import_Has_fuNNy_casING.dart';
+
+void main() {
+  print(dummy);
+}

packages/flutter_tools/test/data/dart_dependencies_test/asci_casing/pubspec.yaml

+name: self

packages/flutter_tools/test/devfs_test.dart

@@ -9,6 +9,7 @@ import 'package:file/file.dart';
 import 'package:file/memory.dart';
 import 'package:flutter_tools/src/asset.dart';
 import 'package:flutter_tools/src/base/io.dart';
+import 'package:flutter_tools/src/base/file_system.dart';
 import 'package:flutter_tools/src/build_info.dart';
 import 'package:flutter_tools/src/devfs.dart';
 import 'package:flutter_tools/src/vmservice.dart';
@@ -121,6 +122,21 @@ void main() {
       FileSystem: () => fs,
     });
 
+    testUsingContext('add new file to local file system and preserve unusal file name casing', () async {
+      final String filePathWithUnusalCasing = fs.path.join('FooBar', 'TEST.txt');
+      final File file = fs.file(fs.path.join(basePath, filePathWithUnusalCasing));
+      await file.parent.create(recursive: true);
+      file.writeAsBytesSync(<int>[1, 2, 3, 4, 5, 6, 7]);
+      final int bytes = await devFS.update();
+      devFSOperations.expectMessages(<String>[
+        'writeFile test FooBar/TEST.txt',
+      ]);
+      expect(devFS.assetPathsToEvict, isEmpty);
+      expect(bytes, 7);
+    }, overrides: <Type, Generator>{
+      FileSystem: () => fs,
+    });
+
     testUsingContext('modify existing file on local file system', () async {
       await devFS.update();
       final File file = fs.file(fs.path.join(basePath, filePath));
@@ -181,7 +197,7 @@ void main() {
         fileFilter.addAll(fs.directory(pkgUri)
             .listSync(recursive: true)
             .where((FileSystemEntity file) => file is File)
-            .map((FileSystemEntity file) => fs.path.canonicalize(file.path))
+            .map((FileSystemEntity file) => canonicalizePath(file.path))
             .toList());
       }
       final int bytes = await devFS.update(fileFilter: fileFilter);

packages/flutter_tools/test/src/base/file_system_test.dart

@@ -59,4 +59,30 @@ void main() {
       expect(sourceMemoryFs.directory(sourcePath).listSync().length, 3);
     });
   });
+
+  group('canonicalizePath', () {
+    test('does not lowercase on Windows', () {
+      String path = 'C:\\Foo\\bAr\\cOOL.dart';
+      expect(canonicalizePath(path), path);
+      // fs.path.canonicalize does lowercase on Windows
+      expect(fs.path.canonicalize(path), isNot(path));
+
+      path = '..\\bar\\.\\\\Foo';
+      final String expected = fs.path.join(fs.currentDirectory.parent.absolute.path, 'bar', 'Foo');
+      expect(canonicalizePath(path), expected);
+      // fs.path.canonicalize should return the same result (modulo casing)
+      expect(fs.path.canonicalize(path), expected.toLowerCase());
+    }, testOn: 'windows');
+
+    test('does not lowercase on posix', () {
+      String path = '/Foo/bAr/cOOL.dart';
+      expect(canonicalizePath(path), path);
+      // fs.path.canonicalize and canonicalizePath should be the same on Posix
+      expect(fs.path.canonicalize(path), path);
+
+      path = '../bar/.//Foo';
+      final String expected = fs.path.join(fs.currentDirectory.parent.absolute.path, 'bar', 'Foo');
+      expect(canonicalizePath(path), expected);
+    }, testOn: 'posix');
+  });
 }