Merge pull request #2612 from microsoft/fix/yaml-empty-strings-to-main

fix: empty strings should be quoted in yaml

Author: baywet

src/Microsoft.OpenApi.YamlReader/YamlConverter.cs

@@ -140,9 +140,10 @@ ScalarStyle.Plain when YamlNullRepresentations.Contains(yaml.Value) => (JsonValu
         }
 
         private static bool NeedsQuoting(string value) =>
+        string.IsNullOrEmpty(value) ||
         decimal.TryParse(value, NumberStyles.Float, CultureInfo.InvariantCulture, out _) ||
-                                   bool.TryParse(value, out _) ||
-                                   YamlNullRepresentations.Contains(value);
+        bool.TryParse(value, out _) ||
+        YamlNullRepresentations.Contains(value);
 
         private static YamlScalarNode ToYamlScalar(this JsonValue val)
         {

test/Microsoft.OpenApi.Readers.Tests/YamlConverterTests.cs

@@ -315,6 +315,23 @@ public void ItDoesNotSerializeTheSentinelValue()
         var scalarNode = Assert.IsType<YamlScalarNode>(yamlValue);
         Assert.Equal("null", scalarNode.Value, StringComparer.OrdinalIgnoreCase);
     }
+    [Fact]
+    public void RoundTripEmptyStringsValues()
+    {
+        // Given
+        var yamlInput =
+        """
+        emptyString: ""
+        """;
+
+        // When
+        var jsonNode = ConvertYamlStringToJsonNode(yamlInput);
+        var convertedBack = jsonNode.ToYamlNode();
+        var convertedBackOutput = ConvertYamlNodeToString(convertedBack);
+
+        // Then
+        Assert.Equal(yamlInput.MakeLineBreaksEnvironmentNeutral(), convertedBackOutput.MakeLineBreaksEnvironmentNeutral());
+    }
 
     private static JsonNode ConvertYamlStringToJsonNode(string yamlInput)
     {