Fix str.splitlines() for \r

Lib/test/string_tests.py

@@ -950,8 +950,6 @@ class BaseTest:
         self.checkequal('Getint', "getInt", 'title')
         self.checkraises(TypeError, 'hello', 'title', 42)
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
     def test_splitlines(self):
         self.checkequal(['abc', 'def', '', 'ghi'], "abc\ndef\n\rghi", 'splitlines')
         self.checkequal(['abc', 'def', '', 'ghi'], "abc\ndef\n\r\nghi", 'splitlines')

vm/src/obj/objstr.rs

@@ -797,11 +797,15 @@ impl PyString {
         let keepends = args.keepends.unwrap_or(false);
         let mut elements = vec![];
         let mut curr = "".to_owned();
-        for ch in self.value.chars() {
-            if ch == '\n' {
+        let mut chars = self.value.chars().peekable();
+        while let Some(ch) = chars.next() {
+            if ch == '\n' || ch == '\r' {
                 if keepends {
                     curr.push(ch);
                 }
+                if ch == '\r' && chars.peek() == Some(&'\n') {
+                    continue;
+                }
                 elements.push(vm.ctx.new_str(curr.clone()));
                 curr.clear();
             } else {