1 files changed, 20 insertions, 0 deletions
diff --git a/spec/ruby/core/string/unpack/shared/basic.rb b/spec/ruby/core/string/unpack/shared/basic.rb
index 332e39d8d1..f636f4689f 100644
--- a/spec/ruby/core/string/unpack/shared/basic.rb
+++ b/spec/ruby/core/string/unpack/shared/basic.rb
@@ -16,6 +16,12 @@ describe :string_unpack_basic, shared: true do
   it "raises a TypeError when passed an Integer" do
     -> { "abc".unpack(1) }.should raise_error(TypeError)
   end
+
+  ruby_version_is "3.1" do
+    it "starts unpacking from the given offset" do
+      "abc".unpack("CC", offset: 1).should == [98, 99]
+    end
+  end
 end
 
 describe :string_unpack_no_platform, shared: true do
@@ -26,4 +32,18 @@ describe :string_unpack_no_platform, shared: true do
   it "raises an ArgumentError when the format modifier is '!'" do
     -> { "abcdefgh".unpack(unpack_format("!")) }.should raise_error(ArgumentError)
   end
+
+  ruby_version_is "3.1" do
+    it "raises an ArgumentError when the offset is negative" do
+      -> { "a".unpack("C", offset: -1) }.should raise_error(ArgumentError)
+    end
+
+    it "returns nil if the offset is at the end of the string" do
+      "a".unpack("C", offset: 1).should == [nil]
+    end
+
+    it "raises an ArgumentError when the offset is larget than the string" do
+      -> { "a".unpack("C", offset: 2) }.should raise_error(ArgumentError)
+    end
+  end
 end