Add spec for CGI.unescapeURIComponent

Also fix typo in test description for UnboundMethod#==.

Author: trinistr

core/unboundmethod/equal_value_spec.rb

@@ -81,7 +81,7 @@
     (@child1 == @parent).should == true
   end
 
-  it "returns false if same method but extracted from two different subclasses" do
+  it "returns true if same method but extracted from two different subclasses" do
     (@child2 == @child1).should == true
     (@child1 == @child2).should == true
   end

library/cgi/unescapeURIComponent_spec.rb

@@ -0,0 +1,68 @@
+require_relative '../../spec_helper'
+
+ruby_version_is ""..."3.5" do
+  require 'cgi'
+end
+ruby_version_is "3.5" do
+  require 'cgi/escape'
+end
+
+describe "CGI.unescapeURIComponent" do
+  it "unescapes whitespace" do
+    string = "%26%3C%3E%22%20%E3%82%86%E3%82%93%E3%82%86%E3%82%93"
+    CGI.unescapeURIComponent(string).should == "&<>\" \xE3\x82\x86\xE3\x82\x93\xE3\x82\x86\xE3\x82\x93"
+  end
+
+  it "does not unescape with unreserved characters" do
+    string = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-._~"
+    CGI.unescapeURIComponent(string).should == "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-._~"
+  end
+
+  it "can produce String with invalid encoding" do
+    string = CGI.unescapeURIComponent("%C0%3C%3C")
+    string.should == "\xC0<<"
+    string.encoding.should == Encoding::UTF_8
+  end
+
+  it "processes String bytes one by one, not characters" do
+    CGI.unescapeURIComponent("%CE%B2").should == "β" # "β" bytes representation is CE B2
+  end
+
+  it "raises a TypeError with nil" do
+    -> {
+      CGI.unescapeURIComponent(nil)
+    }.should raise_error(TypeError, 'no implicit conversion of nil into String')
+  end
+
+  it "unencodes empty string" do
+    CGI.unescapeURIComponent("").should == ""
+  end
+
+  it "unencodes single whitespace" do
+    CGI.unescapeURIComponent("%20").should == " "
+  end
+
+  it "unencodes double whitespace" do
+    CGI.unescapeURIComponent("%20%20").should == "  "
+  end
+
+  it "does not preserve encoding" do
+    string = "whatever".encode("ASCII-8BIT")
+    CGI.unescapeURIComponent(string).encoding.should == Encoding::UTF_8
+  end
+
+  it "decodes using a specified Encoding" do
+    string = CGI.unescapeURIComponent("%D2%3C%3C", "ISO-8859-1")
+    string.encoding.should == Encoding::ISO_8859_1
+    string.should == "Ò<<".encode("ISO-8859-1")
+  end
+
+  it "uses implicit type conversion to String" do
+    object = Object.new
+    def object.to_str
+      "a%20b"
+    end
+
+    CGI.unescapeURIComponent(object).should == "a b"
+  end
+end