[YAML][NFC] precommit wrong test case (llvm#131782)

Author: HerrCai0907

llvm/unittests/Support/YAMLIOTest.cpp

@@ -1273,6 +1273,36 @@ TEST(YAMLIO, TestReadWriteBlockScalarValue) {
   }
 }
 
+struct V {
+  MultilineStringType doc;
+  std::string str;
+};
+template <> struct 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
 //===----------------------------------------------------------------------===//