1 files changed, 83 insertions, 0 deletions
diff --git a/spec/ruby/language/regexp/repetition_spec.rb b/spec/ruby/language/regexp/repetition_spec.rb
index 7bb767ccaf..295b3bf553 100644
--- a/spec/ruby/language/regexp/repetition_spec.rb
+++ b/spec/ruby/language/regexp/repetition_spec.rb
@@ -45,4 +45,87 @@ describe "Regexps with repetition" do
     /a?/.match("aaa").to_a.should == ["a"]
     /a?/.match("bbb").to_a.should == [""]
   end
+
+  it "handles incomplete range quantifiers" do
+    /a{}/.match("a{}")[0].should == "a{}"
+    /a{,}/.match("a{,}")[0].should == "a{,}"
+    /a{1/.match("a{1")[0].should == "a{1"
+    /a{1,2/.match("a{1,2")[0].should == "a{1,2"
+    /a{,5}/.match("aaa")[0].should == "aaa"
+  end
+
+  it "lets us use quantifiers on assertions" do
+    /a^?b/.match("ab")[0].should == "ab"
+    /a$?b/.match("ab")[0].should == "ab"
+    /a\A?b/.match("ab")[0].should == "ab"
+    /a\Z?b/.match("ab")[0].should == "ab"
+    /a\z?b/.match("ab")[0].should == "ab"
+    /a\G?b/.match("ab")[0].should == "ab"
+    /a\b?b/.match("ab")[0].should == "ab"
+    /a\B?b/.match("ab")[0].should == "ab"
+    /a(?=c)?b/.match("ab")[0].should == "ab"
+    /a(?!=b)?b/.match("ab")[0].should == "ab"
+    /a(?<=c)?b/.match("ab")[0].should == "ab"
+    /a(?<!a)?b/.match("ab")[0].should == "ab"
+  end
+
+  it "does not delete optional assertions" do
+    /(?=(a))?/.match("a").to_a.should == [ "", "a" ]
+  end
+
+  it "supports nested quantifiers" do
+    suppress_warning do
+      eval <<-RUBY
+      /a***/.match("aaa")[0].should == "aaa"
+
+      # a+?* should not be reduced, it should be equivalent to (a+?)*
+      # NB: the capture group prevents regex engines from reducing the two quantifiers
+      # https://bugs.ruby-lang.org/issues/17341
+      /a+?*/.match("")[0].should == ""
+      /(a+?)*/.match("")[0].should == ""
+
+      /a+?*/.match("a")[0].should == "a"
+      /(a+?)*/.match("a")[0].should == "a"
+
+      ruby_bug '#17341', ''...'3.0' do
+        /a+?*/.match("aa")[0].should == "aa"
+      end
+      /(a+?)*/.match("aa")[0].should == "aa"
+
+      # a+?+ should not be reduced, it should be equivalent to (a+?)+
+      # https://bugs.ruby-lang.org/issues/17341
+      /a+?+/.match("").should == nil
+      /(a+?)+/.match("").should == nil
+
+      /a+?+/.match("a")[0].should == "a"
+      /(a+?)+/.match("a")[0].should == "a"
+
+      ruby_bug '#17341', ''...'3.0' do
+        /a+?+/.match("aa")[0].should == "aa"
+      end
+      /(a+?)+/.match("aa")[0].should == "aa"
+
+      # both a**? and a+*? should be equivalent to (a+)??
+      # this quantifier would rather match nothing, but if that's not possible,
+      # it will greedily take everything
+      /a**?/.match("")[0].should == ""
+      /(a*)*?/.match("")[0].should == ""
+      /a+*?/.match("")[0].should == ""
+      /(a+)*?/.match("")[0].should == ""
+      /(a+)??/.match("")[0].should == ""
+
+      /a**?/.match("aaa")[0].should == ""
+      /(a*)*?/.match("aaa")[0].should == ""
+      /a+*?/.match("aaa")[0].should == ""
+      /(a+)*?/.match("aaa")[0].should == ""
+      /(a+)??/.match("aaa")[0].should == ""
+
+      /b.**?b/.match("baaabaaab")[0].should == "baaabaaab"
+      /b(.*)*?b/.match("baaabaaab")[0].should == "baaabaaab"
+      /b.+*?b/.match("baaabaaab")[0].should == "baaabaaab"
+      /b(.+)*?b/.match("baaabaaab")[0].should == "baaabaaab"
+      /b(.+)??b/.match("baaabaaab")[0].should == "baaabaaab"
+      RUBY
+    end
+  end
 end