Log verbose output when testing pub.

sdk/lib/_internal/pub/lib/src/io.dart

Index: sdk/lib/_internal/pub/lib/src/io.dart
diff --git a/sdk/lib/_internal/pub/lib/src/io.dart b/sdk/lib/_internal/pub/lib/src/io.dart
index da220e4a537f40fc1a7264f87ad3f9e2cee8234e..122bcf0c8edc260e535eca5148b87e276a3bdcbc 100644
--- a/sdk/lib/_internal/pub/lib/src/io.dart
+++ b/sdk/lib/_internal/pub/lib/src/io.dart
@@ -404,7 +404,11 @@ final Stream<String> stdinLines = streamToLines(
 /// should just be a fragment like, "Are you sure you want to proceed".
 Future<bool> confirm(String message) {
   log.fine('Showing confirm message: $message');
-  stdout.write("$message (y/n)? ");
+  if (runningAsTest) {
+    log.message("$message (y/n)?");
+  } else {
+    stdout.write("$message (y/n)? ");
+  }
   return streamFirst(stdinLines)
       .then((line) => new RegExp(r"^[yY]").hasMatch(line));
 }