[cross_file] Fix accidental constructor change (#3131)

* [cross_file] Fix accidental constructor change

In #3095 I accidentally changed
a constructor argument's nullability because of a misleading analyzer
warning. That version has been retracted; this restores the original
behavior.

* Add a test

* Better implementation

Author: stuartmorgan-g

packages/cross_file/CHANGELOG.md

@@ -1,5 +1,10 @@
+## 0.3.3+4
+
+* Reverts an accidental change in a constructor argument's nullability.
+
 ## 0.3.3+3
 
+* **RETRACTED**
 * Updates code to fix strict-cast violations.
 * Updates minimum SDK version to Flutter 3.0.
 

packages/cross_file/lib/src/types/interface.dart

@@ -22,7 +22,7 @@ class XFile extends XFileBase {
   /// `path` of the file doesn't match what the user sees when selecting it
   /// (like in web)
   XFile(
-    super.path, {
+    String super.path, {
     String? mimeType,
     String? name,
     int? length,

packages/cross_file/pubspec.yaml

@@ -2,7 +2,7 @@ name: cross_file
 description: An abstraction to allow working with files across multiple platforms.
 repository: https://github.com/flutter/packages/tree/main/packages/cross_file
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+cross_file%22
-version: 0.3.3+3
+version: 0.3.3+4
 
 environment:
   sdk: ">=2.17.0 <3.0.0"

packages/cross_file/test/x_file_io_test.dart

@@ -70,6 +70,10 @@ void main() {
 
       await tempDir.delete(recursive: true);
     });
+
+    test('nullability is correct', () async {
+      expect(_ensureNonnullPathArgument('a/path'), isNotNull);
+    });
   });
 
   group('Create with data', () {
@@ -107,6 +111,13 @@ void main() {
   });
 }
 
+// This is to create an analysis error if the version of XFile in
+// interface.dart, which should never actually be used but is what the analyzer
+// runs against, has the nullability of `path` changed.
+XFile _ensureNonnullPathArgument(String? path) {
+  return XFile(path!);
+}
+
 /// An XFile subclass that tracks reads, for testing purposes.
 class TestXFile extends XFile {
   TestXFile(super.path);