patch 8.2.4534: Vim9: "is" operator with empty string and null returns true
Problem: Vim9: "is" operator with empty string and null returns true.
Solution: Consider empty string and null to be different for "is".
diff --git a/src/testdir/test_vim9_expr.vim b/src/testdir/test_vim9_expr.vim
index 4a3803a..72e85de 100644
--- a/src/testdir/test_vim9_expr.vim
+++ b/src/testdir/test_vim9_expr.vim
@@ -801,6 +801,13 @@
assert_false(null_string != null)
assert_false(v:null != test_null_string())
assert_false(null != null_string)
+
+ assert_true(null_string is test_null_string())
+ assert_false(null_string is '')
+ assert_false('' is null_string)
+ assert_false(null_string isnot test_null_string())
+ assert_true(null_string isnot '')
+ assert_true('' isnot null_string)
END
v9.CheckDefAndScriptSuccess(lines)
unlet g:null_dict