Add test cases for building document with empty strings

test/CMakeLists.txt

@@ -75,6 +75,7 @@ ryml_add_test(yaml_events)
 ryml_add_test_case_group(empty_file)
 ryml_add_test_case_group(empty_map)
 ryml_add_test_case_group(empty_seq)
+ryml_add_test_case_group(empty_scalar)
 ryml_add_test_case_group(simple_doc)
 ryml_add_test_case_group(simple_map)
 ryml_add_test_case_group(simple_seq)

test/test_empty_scalar.cpp

@@ -0,0 +1,89 @@
+#include "./test_group.hpp"
+#include "c4/error.hpp"
+#include "c4/yml/node.hpp"
+#include "c4/yml/parse.hpp"
+#include "c4/yml/tree.hpp"
+#include <gtest/gtest.h>
+#include <string>
+
+namespace c4 {
+namespace yml {
+
+/**
+    See also issue 263.
+ */
+
+C4_SUPPRESS_WARNING_GCC_WITH_PUSH("-Wuseless-cast")
+
+constexpr const NodeType_e DQV = (NodeType_e)(DOC | QV);
+
+TEST(empty_scalar, parse_zero_length_strings)
+{
+    char inp[] = R"(
+- ""
+- ''
+- >
+- |
+)";
+
+    Tree tr = parse_in_place(inp);
+
+    ASSERT_EQ(tr.rootref().num_children(), 4);
+    for(const auto &child : tr.rootref().children())
+    {
+        ASSERT_EQ(child.type(), QV);
+        ASSERT_EQ(child.val(), "");
+        ASSERT_FALSE(child.val_is_null());
+    }
+}
+
+TEST(empty_scalar, build_zero_length_string)
+{
+    Tree tr;
+    NodeRef root = tr.rootref();
+    root |= MAP;
+
+    NodeRef non_quoted = root["non_quoted"];
+    non_quoted |= SEQ;
+
+    const std::string e;  // empty std::string
+
+    non_quoted.append_child() << "";
+    non_quoted.append_child() = "";
+    non_quoted.append_child() << e;
+
+    NodeRef quoted = root["quoted"];
+    quoted |= SEQ;
+    {auto r = quoted.append_child(); r << ""; r.set_type(r.type() | VALQUO);}
+    {auto r = quoted.append_child(); r = "";  r.set_type(r.type() | VALQUO);}
+    {auto r = quoted.append_child(); r << e;  r.set_type(r.type() | VALQUO);}
+
+    ASSERT_EQ(non_quoted.num_children(), 3);
+    for(const auto &child : non_quoted.children())
+    {
+        EXPECT_EQ(child.type(), VAL);
+        EXPECT_EQ(child.val(), "");
+        EXPECT_FALSE(child.val_is_null());
+    }
+
+    ASSERT_EQ(quoted.num_children(), 3);
+    for(const auto &child : quoted.children())
+    {
+        EXPECT_EQ(child.type(), VAL | VALQUO);
+        EXPECT_EQ(child.val(), "");
+        EXPECT_FALSE(child.val_is_null());
+    }
+}
+
+CASE_GROUP(EMPTY_SCALAR)
+{
+ADD_CASE_TO_GROUP("empty scalar, single quoted",
+                  "''",
+                  N(DQV, "")
+);
+}
+
+} // namespace yml
+} // namespace c4
+
+C4_SUPPRESS_WARNING_GCC_POP