1 files changed, 12 insertions, 5 deletions
diff --git a/spec/ruby/core/string/unpack/shared/basic.rb b/spec/ruby/core/string/unpack/shared/basic.rb
index b37a447683..734630bda0 100644
--- a/spec/ruby/core/string/unpack/shared/basic.rb
+++ b/spec/ruby/core/string/unpack/shared/basic.rb
@@ -9,12 +9,19 @@ describe :string_unpack_basic, shared: true do
     "abc".unpack(d).should be_an_instance_of(Array)
   end
 
+  ruby_version_is ""..."3.3" do
+    it "warns about using an unknown directive" do
+      -> { "abcdefgh".unpack("a R" + unpack_format) }.should complain(/unknown unpack directive 'R' in 'a R#{unpack_format}'/)
+      -> { "abcdefgh".unpack("a 0" + unpack_format) }.should complain(/unknown unpack directive '0' in 'a 0#{unpack_format}'/)
+      -> { "abcdefgh".unpack("a :" + unpack_format) }.should complain(/unknown unpack directive ':' in 'a :#{unpack_format}'/)
+    end
+  end
+
   ruby_version_is "3.3" do
-    # https://bugs.ruby-lang.org/issues/19150
-    it 'raise ArgumentError when a directive is unknown' do
-      -> { "abcdefgh".unpack("a R" + unpack_format) }.should raise_error(ArgumentError, /unknown unpack directive 'R'/)
-      -> { "abcdefgh".unpack("a 0" + unpack_format) }.should raise_error(ArgumentError, /unknown unpack directive '0'/)
-      -> { "abcdefgh".unpack("a :" + unpack_format) }.should raise_error(ArgumentError, /unknown unpack directive ':'/)
+    it "raises ArgumentError when a directive is unknown" do
+      -> { "abcdefgh".unpack("a K" + unpack_format) }.should raise_error(ArgumentError, "unknown unpack directive 'K' in 'a K#{unpack_format}'")
+      -> { "abcdefgh".unpack("a 0" + unpack_format) }.should raise_error(ArgumentError, "unknown unpack directive '0' in 'a 0#{unpack_format}'")
+      -> { "abcdefgh".unpack("a :" + unpack_format) }.should raise_error(ArgumentError, "unknown unpack directive ':' in 'a :#{unpack_format}'")
     end
   end
 end