feat(logger): add link

packages/mason_logger/lib/mason_logger.dart

@@ -2,4 +2,5 @@ library mason_logger;
 
 export 'src/io.dart';
 export 'src/level.dart';
+export 'src/link_wrap.dart';
 export 'src/mason_logger.dart' show Logger, Progress;

packages/mason_logger/lib/src/link_wrap.dart

@@ -0,0 +1,8 @@
+/// Helper function for "wrapping" an optional message with link.
+String linkWrap(String? message, Uri uri) {
+  const lead = '\x1B]8;;';
+  const trail = '\x1B\\';
+
+  final encoded = '$lead$uri$trail${message ?? uri}$lead$trail';
+  return encoded;
+}

packages/mason_logger/lib/src/mason_logger.dart

@@ -6,6 +6,9 @@ import 'package:mason_logger/mason_logger.dart';
 
 part 'progress.dart';
 
+/// Callback for writing to `stdout` or `stderr`.
+typedef StdoutWriter = void Function(String?);
+
 /// {@template logger}
 /// A basic Logger which wraps `stdio` and applies various styles.
 /// {@endtemplate}
@@ -49,6 +52,21 @@ class Logger {
     _stdout.writeln(message);
   }
 
+  /// Writes a message with a clickable link.
+  /// By default writes to `stdout` with [info], but any [StdoutWriter] works.
+  ///
+  /// **NOTE**: Only works on supported terminal emulators. Please see this
+  /// [link on what is supported](https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda#supporting-apps).
+  void link(
+    String? message,
+    Uri uri, [
+    StdoutWriter? writer,
+  ]) {
+    final _writer = writer ?? info;
+    final _message = linkWrap(message, uri);
+    _writer(_message);
+  }
+
   /// Writes delayed message to stdout.
   void delayed(String? message) => _queue.add(message);
 

packages/mason_logger/test/src/link_wrap_test.dart

@@ -0,0 +1,32 @@
+import 'package:mason_logger/mason_logger.dart';
+import 'package:test/test.dart';
+
+void main() {
+  group('linkWrap', () {
+    final uri = Uri.parse('https://github.com/felangel/mason/issues/');
+    const lead = '\x1B]8;;';
+    const trail = '\x1B\\';
+    test(
+      'builds output with correct encodings: ' r'\x1B]8;;' ' and ' r'\x1B\\',
+      () {
+        const message = 'message';
+
+        final output = linkWrap(message, uri);
+        final matcher = stringContainsInOrder(
+          [lead, '$uri', trail, message, lead, trail],
+        );
+
+        expect(output, matcher);
+      },
+    );
+
+    test('builds String with Uri when message is null: ', () {
+      final output = linkWrap(null, uri);
+      final matcher = stringContainsInOrder(
+        [lead, '$uri', trail, '$uri', lead, trail],
+      );
+
+      expect(output, matcher);
+    });
+  });
+}

packages/mason_logger/test/src/mason_logger_test.dart

@@ -22,6 +22,47 @@ void main() {
       when(() => stdout.supportsAnsiEscapes).thenReturn(true);
     });
 
+    group('.link', () {
+      final uri = Uri.parse('https://github.com/felangel/mason/issues/');
+
+      test(
+        'writes to stdout',
+        () {
+          IOOverrides.runZoned(
+            () {
+              const message = 'test message';
+              const lead = '\x1B]8;;';
+              const trail = '\x1B\\';
+
+              Logger().link(message, uri);
+              verify(
+                () => stdout.writeln('$lead$uri$trail$message$lead$trail'),
+              ).called(1);
+            },
+            stdout: () => stdout,
+          );
+        },
+      );
+
+      test(
+        'writes with the provided writer',
+        () {
+          IOOverrides.runZoned(
+            () {
+              const message = 'test message';
+              const lead = '\x1B]8;;';
+              const trail = '\x1B\\';
+              Logger().link(message, uri, stdout.write);
+              verify(
+                () => stdout.write('$lead$uri$trail$message$lead$trail'),
+              ).called(1);
+            },
+            stdout: () => stdout,
+          );
+        },
+      );
+    });
+
     group('level', () {
       test('is mutable', () {
         final logger = Logger();