[file_selector] Add allowsAny to XTypeGroup (flutter#6094)

Author: stuartmorgan-g

packages/file_selector/file_selector_platform_interface/CHANGELOG.md

@@ -1,6 +1,7 @@
-## NEXT
+## 2.1.0
 
-* Removes unnecessary imports.
+* Adds `allowsAny` to `XTypeGroup` as a simple and future-proof way of identifying
+  wildcard groups.
 
 ## 2.0.4
 

packages/file_selector/file_selector_platform_interface/lib/src/types/x_type_group/x_type_group.dart

@@ -42,6 +42,14 @@ class XTypeGroup {
     };
   }
 
+  /// True if this type group should allow any file.
+  bool get allowsAny {
+    return (extensions?.isEmpty ?? true) &&
+        (mimeTypes?.isEmpty ?? true) &&
+        (macUTIs?.isEmpty ?? true) &&
+        (webWildCards?.isEmpty ?? true);
+  }
+
   static List<String>? _removeLeadingDots(List<String>? exts) => exts
       ?.map((String ext) => ext.startsWith('.') ? ext.substring(1) : ext)
       .toList();

packages/file_selector/file_selector_platform_interface/pubspec.yaml

@@ -4,7 +4,7 @@ repository: https://github.com/flutter/plugins/tree/main/packages/file_selector/
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+file_selector%22
 # NOTE: We strongly prefer non-breaking changes, even at the expense of a
 # less-clean API. See https://flutter.dev/go/platform-interface-breaking-changes
-version: 2.0.4
+version: 2.1.0
 
 environment:
   sdk: ">=2.12.0 <3.0.0"

packages/file_selector/file_selector_platform_interface/test/x_type_group_test.dart

@@ -40,6 +40,35 @@ void main() {
       expect(jsonMap['mimeTypes'], null);
       expect(jsonMap['macUTIs'], null);
       expect(jsonMap['webWildCards'], null);
+      expect(group.allowsAny, true);
+    });
+
+    test('allowsAny treats empty arrays the same as null', () {
+      final XTypeGroup group = XTypeGroup(
+        label: 'Any',
+        extensions: <String>[],
+        mimeTypes: <String>[],
+        macUTIs: <String>[],
+        webWildCards: <String>[],
+      );
+
+      expect(group.allowsAny, true);
+    });
+
+    test('allowsAny returns false if anything is set', () {
+      final XTypeGroup extensionOnly =
+          XTypeGroup(label: 'extensions', extensions: <String>['txt']);
+      final XTypeGroup mimeOnly =
+          XTypeGroup(label: 'mime', mimeTypes: <String>['text/plain']);
+      final XTypeGroup utiOnly =
+          XTypeGroup(label: 'utis', macUTIs: <String>['public.text']);
+      final XTypeGroup webOnly =
+          XTypeGroup(label: 'web', webWildCards: <String>['.txt']);
+
+      expect(extensionOnly.allowsAny, false);
+      expect(mimeOnly.allowsAny, false);
+      expect(utiOnly.allowsAny, false);
+      expect(webOnly.allowsAny, false);
     });
 
     test('Leading dots are removed from extensions', () {