Manually write JSON

src/Exercism.TestRunner.CSharp/TestRun.cs

@@ -11,37 +11,19 @@ internal enum TestStatus
 
     internal class TestResult
     {
-        [JsonPropertyName("name")]
         public string Name { get; set; }
-
-        [JsonPropertyName("status")]
         public TestStatus Status { get; set; }
-
-        [JsonPropertyName("task_id")]
         public int? TaskId { get; set; }
-
-        [JsonPropertyName("message")]
         public string Message { get; set; }
-
-        [JsonPropertyName("output")]
         public string Output { get; set; }
-
-        [JsonPropertyName("test_code")]
         public string TestCode { get; set; }
     }
 
     internal class TestRun
     {
-        [JsonPropertyName("version")]
         public int Version { get; set; } = 3;
-
-        [JsonPropertyName("status")]
         public TestStatus Status { get; set; }
-
-        [JsonPropertyName("message")]
         public string Message { get; set; }
-
-        [JsonPropertyName("tests")]
         public TestResult[] Tests { get; set; }
     }
 }

src/Exercism.TestRunner.CSharp/TestRunWriter.cs

@@ -1,30 +1,59 @@
 using System.IO;
 using System.Text.Json;
-using System.Text.Json.Serialization;
 
 namespace Exercism.TestRunner.CSharp
 {
     internal static class TestRunWriter
     {
-        public static void WriteToFile(this TestRun testRun, Options options) =>
-            File.WriteAllText(options.ResultsJsonPath(), testRun.ToJson());
+        private static readonly JsonWriterOptions JsonWriterOptions = new() {Indented = true};
 
-        private static string ResultsJsonPath(this Options options) =>
-            Path.GetFullPath(Path.Combine(options.OutputDirectory, "results.json"));
-
-        private static string ToJson(this TestRun testRun) =>
-            JsonSerializer.Serialize(testRun, CreateJsonSerializerOptions());
-
-        private static JsonSerializerOptions CreateJsonSerializerOptions()
+        public static void WriteToFile(this TestRun testRun, Options options)
+        {
+            using var fileStream = File.Create(options.ResultsJsonPath());
+            using var jsonWriter = new Utf8JsonWriter(fileStream, JsonWriterOptions);
+            jsonWriter.WriteStartObject();
+            jsonWriter.WriteNumber("version", testRun.Version);
+            jsonWriter.WriteString("status", testRun.Status.ToString().ToLower());
+            jsonWriter.WriteStringIfNotEmpty("message", testRun.Message);
+            jsonWriter.WriteTestResults(testRun.Tests);
+            jsonWriter.WriteEndObject();
+            jsonWriter.Flush();
+            fileStream.WriteByte((byte)'\n');
+        }
+
+        private static void WriteTestResults(this Utf8JsonWriter jsonWriter, TestResult[] testResults)
         {
-            var options = new JsonSerializerOptions
+            if (testResults.Length == 0)
+                return;
+
+            jsonWriter.WriteStartArray("tests");
+
+            foreach (var testResult in testResults)
             {
-                DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull,
-                WriteIndented = true,
-            };
-            options.Converters.Add(new JsonStringEnumConverter(JsonNamingPolicy.CamelCase));
+                jsonWriter.WriteStartObject();
+                jsonWriter.WriteString("name", testResult.Name);
+                jsonWriter.WriteString("status", testResult.Status.ToString().ToLower());
+                if (testResult.TaskId.HasValue)
+                    jsonWriter.WriteNumber("task_id", testResult.TaskId.Value);
+                jsonWriter.WriteStringIfNotEmpty("message", testResult.Message);
+                jsonWriter.WriteStringIfNotEmpty("output", testResult.Output);
+                jsonWriter.WriteStringIfNotEmpty("test_code", testResult.TestCode);
+                jsonWriter.WriteEndObject();
+            }
+
+            jsonWriter.WriteEndArray();
+        }
 
-            return options;
+        private static void WriteStringIfNotEmpty(this Utf8JsonWriter jsonWriter, string property, string value)
+        {
+            if (string.IsNullOrWhiteSpace(value))
+                return;
+
+            jsonWriter.WriteString(property, value);
         }
+
+
+        private static string ResultsJsonPath(this Options options) =>
+            Path.GetFullPath(Path.Combine(options.OutputDirectory, "results.json"));
     }
 }