[llvm] Reapply "[YAML][NFC] precommit wrong test case (#131782)" (PR #132936)

[Congcong Cai via llvm-commits]

https://github.com/HerrCai0907 created https://github.com/llvm/llvm-project/pull/132936

This reverts commit 64779455b8f4875c7de690dd4c3e324dbbcb3029.


>From aa83e10f8c0cf080b569b2cc507116c7357af04d Mon Sep 17 00:00:00 2001
From: Congcong Cai <congcongcai0907 at 163.com>
Date: Tue, 25 Mar 2025 14:09:10 +0000
Subject: [PATCH] Reapply "[YAML][NFC] precommit wrong test case (#131782)"

This reverts commit 64779455b8f4875c7de690dd4c3e324dbbcb3029.
---
 llvm/unittests/Support/YAMLIOTest.cpp | 30 +++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/llvm/unittests/Support/YAMLIOTest.cpp b/llvm/unittests/Support/YAMLIOTest.cpp
index c0e9c57a77f19..f03563cd5bc2e 100644
--- a/llvm/unittests/Support/YAMLIOTest.cpp
+++ b/llvm/unittests/Support/YAMLIOTest.cpp
@@ -1273,6 +1273,36 @@ TEST(YAMLIO, TestReadWriteBlockScalarValue) {
   }
 }
 
+struct V {
+  MultilineStringType doc;
+  std::string str;
+};
+template <> struct llvm::yaml::MappingTraits<V> {
+  static void mapping(IO &io, V &v) {
+    io.mapRequired("block_scalac", v.doc);
+    io.mapRequired("scalar", v.str);
+  }
+};
+template <> struct llvm::yaml::SequenceElementTraits<V> {
+  static const bool flow = false;
+};
+TEST(YAMLIO, TestScalarAfterBlockScalar) {
+  std::vector<V> v{V{}};
+  v[0].doc.str = "AA\nBB";
+  v[0].str = "a";
+  std::string output;
+  llvm::raw_string_ostream ostr(output);
+  Output yout(ostr);
+  yout << v;
+  EXPECT_EQ(output, R"(---
+- block_scalac:     |
+    AA
+    BB
+scalar:          a
+...
+)");
+}
+
 //===----------------------------------------------------------------------===//
 //  Test flow sequences
 //===----------------------------------------------------------------------===//