[ruby/pathname] Add more tests for Pathname#initialize

ruby/pathname@a2edd25bc1

Author: nobu

test/pathname/test_pathname.rb

@@ -485,6 +485,13 @@ def test_initialize
     p2 = Pathname.new(p1)
     assert_equal(p1, p2)
 
+    obj = Object.new
+    assert_raise(TypeError) { Pathname.new(obj) }
+
+    obj = Object.new
+    def obj.to_path; "a/path"; end
+    assert_equal("a/path", Pathname.new(obj).to_s)
+
     obj = Object.new
     def obj.to_str; "a/b"; end
     assert_equal("a/b", Pathname.new(obj).to_s)
@@ -494,6 +501,10 @@ def test_initialize_nul
     assert_raise(ArgumentError) { Pathname.new("a\0") }
   end
 
+  def test_initialize_encoding
+    assert_raise(Encoding::CompatibilityError) { Pathname.new("a".encode(Encoding::UTF_32BE)) }
+  end
+
   def test_global_constructor
     p = Pathname.new('a')
     assert_equal(p, Pathname('a'))