[Bug #19784] Fix behaviors against prefix with broken encoding

- String#start_with?
- String#delete_prefix
- String#delete_prefix!

2 files changed, 10 insertions, 6 deletions

diff --git a/spec/ruby/core/string/start_with_spec.rb b/spec/ruby/core/string/start_with_spec.rb
index 3833289f96..81eed47f96 100644
--- a/spec/ruby/core/string/start_with_spec.rb
+++ b/spec/ruby/core/string/start_with_spec.rb
@@ -7,12 +7,14 @@ describe "String#start_with?" do
   it_behaves_like :start_with, :to_s
 
   # Here and not in the shared examples because this is invalid as a Symbol
-  it "does not check that we are not starting to match at the head of a character" do
+  it "matches part of a character with the same part" do
     "\xA9".should.start_with?("\xA9") # A9 is not a character head for UTF-8
   end
 
-  it "does not check we are matching only part of a character" do
-    "\xe3\x81\x82".size.should == 1
-    "\xe3\x81\x82".should.start_with?("\xe3")
+  ruby_bug "#19784", ""..."3.3" do
+    it "checks we are matching only part of a character" do
+      "\xe3\x81\x82".size.should == 1
+      "\xe3\x81\x82".should_not.start_with?("\xe3")
+    end
   end
 end
diff --git a/spec/ruby/shared/string/start_with.rb b/spec/ruby/shared/string/start_with.rb
index 6932a017b6..91fc50c4cd 100644
--- a/spec/ruby/shared/string/start_with.rb
+++ b/spec/ruby/shared/string/start_with.rb
@@ -70,7 +70,9 @@ describe :start_with, shared: true do
     $1.should be_nil
   end
 
-  it "does not check that we are not matching part of a character" do
-    "\xC3\xA9".send(@method).should.start_with?("\xC3")
+  ruby_bug "#19784", ""..."3.3" do
+    it "checks that we are not matching part of a character" do
+      "\xC3\xA9".send(@method).should_not.start_with?("\xC3")
+    end
   end
 end