Add RFC3339 formats with offset

src/KubernetesClient/KubernetesJson.cs

@@ -24,7 +24,7 @@
             public override void Write(Utf8JsonWriter writer, TimeSpan value, JsonSerializerOptions options)
             {
                 var iso8601TimeSpanString = XmlConvert.ToString(value); // XmlConvert for TimeSpan uses ISO8601, so delegate serialization to it
                 writer.WriteStringValue(iso8601TimeSpanString);
             }
         }
 
@@ -34,27 +34,34 @@
             private const string RFC3339NanoFormat = "yyyy-MM-dd'T'HH':'mm':'ss.fffffffZ";
             private const string RFC3339Format = "yyyy'-'MM'-'dd'T'HH':'mm':'ssZ";
 
+            private const string RFC3339MicroWithOffsetFormat = "yyyy'-'MM'-'dd'T'HH':'mm':'ss.ffffffK";
+            private const string RFC3339NanoWithOffsetFormat = "yyyy-MM-dd'T'HH':'mm':'ss.fffffffK";
+            private const string RFC3339WithOffsetFormat = "yyyy'-'MM'-'dd'T'HH':'mm':'ssK";
+
+            private static readonly string[] StandardFormats = { RFC3339Format, RFC3339MicroFormat, RFC3339WithOffsetFormat, RFC3339MicroWithOffsetFormat };
+            private static readonly string[] NanoFormats = { RFC3339NanoFormat, RFC3339NanoWithOffsetFormat };
+
             public override DateTimeOffset Read(ref Utf8JsonReader reader, Type typeToConvert, JsonSerializerOptions options)
             {
                 var str = reader.GetString();
 
-                if (DateTimeOffset.TryParseExact(str, new[] { RFC3339Format, RFC3339MicroFormat }, CultureInfo.InvariantCulture, DateTimeStyles.None, out var result))
+                // Try standard formats first
+                if (DateTimeOffset.TryParseExact(str, StandardFormats, CultureInfo.InvariantCulture, DateTimeStyles.None, out var result))
                 {
                     return result;
                 }
 
-                // try RFC3339NanoLenient by trimming 1-9 digits to 7 digits
+                // Try RFC3339NanoLenient by trimming 1-9 digits to 7 digits
                 var originalstr = str;
                 str = Regex.Replace(str, @"\.\d+", m => (m.Value + "000000000").Substring(0, 7 + 1)); // 7 digits + 1 for the dot
-                if (DateTimeOffset.TryParseExact(str, new[] { RFC3339NanoFormat }, CultureInfo.InvariantCulture, DateTimeStyles.None, out result))
+                if (DateTimeOffset.TryParseExact(str, NanoFormats, CultureInfo.InvariantCulture, DateTimeStyles.None, out result))
                 {
                     return result;
                 }
 
                 throw new FormatException($"Unable to parse {originalstr} as RFC3339 RFC3339Micro or RFC3339Nano");
             }
 
-
             public override void Write(Utf8JsonWriter writer, DateTimeOffset value, JsonSerializerOptions options)
             {
                 // Output as RFC3339Micro
@@ -66,7 +73,7 @@
                 {
                     // No fractional seconds - use format without fractional part
                     var basePart = date.ToString("yyyy-MM-dd'T'HH:mm:ss", CultureInfo.InvariantCulture);
                     writer.WriteStringValue(basePart + "Z");
                 }
                 else
                 {
@@ -180,7 +187,7 @@
         public static string Serialize(object value, JsonSerializerOptions jsonSerializerOptions = null)
         {
 #if NET8_0_OR_GREATER
             var info = (jsonSerializerOptions ?? JsonSerializerOptions).GetTypeInfo(value.GetType());
             return JsonSerializer.Serialize(value, info);
 #else
             return JsonSerializer.Serialize(value, jsonSerializerOptions ?? JsonSerializerOptions);
@@ -190,7 +197,7 @@
         public static string Serialize(JsonDocument value, JsonSerializerOptions jsonSerializerOptions = null)
         {
 #if NET8_0_OR_GREATER
             var info = (jsonSerializerOptions ?? JsonSerializerOptions).GetTypeInfo(value.GetType());
             return JsonSerializer.Serialize(value, info);
 #else
             return JsonSerializer.Serialize(value, jsonSerializerOptions ?? JsonSerializerOptions);
@@ -210,7 +217,7 @@
         public static string Serialize(JsonNode value, JsonSerializerOptions jsonSerializerOptions = null)
         {
 #if NET8_0_OR_GREATER
             var info = (jsonSerializerOptions ?? JsonSerializerOptions).GetTypeInfo(value.GetType());
             return JsonSerializer.Serialize(value, info);
 #else
             return JsonSerializer.Serialize(value, jsonSerializerOptions ?? JsonSerializerOptions);

tests/KubernetesClient.Tests/KubernetesJsonTests.cs

@@ -169,4 +169,36 @@ public void DateTimeWithFractionalSecondsAlwaysHasSixDigits()
         // Also verify it doesn't have 5 digits (which would fail in Kubernetes)
         Assert.DoesNotContain("2025-11-17T22:52:34.96217Z", json);
     }
+
+    [Fact]
+    public void DateTimeWithTimezoneOffsetParsesCorrectly()
+    {
+        // Test that datetime with explicit timezone offset (e.g., +00:00) is parsed correctly
+        // This uses the "last resort" general DateTimeOffset parsing fallback
+        var json = "{\"metadata\":{\"creationTimestamp\":\"2025-12-12T16:16:55.079293+00:00\"}}";
+
+        var secret = KubernetesJson.Deserialize<V1Secret>(json);
+
+        Assert.NotNull(secret.Metadata?.CreationTimestamp);
+        var dt = secret.Metadata.CreationTimestamp.Value;
+
+        Assert.Equal(2025, dt.Year);
+        Assert.Equal(12, dt.Month);
+        Assert.Equal(12, dt.Day);
+        Assert.Equal(16, dt.Hour);
+        Assert.Equal(16, dt.Minute);
+        Assert.Equal(55, dt.Second);
+        Assert.Equal(79, dt.Millisecond);
+#if NET7_0_OR_GREATER
+        Assert.Equal(293, dt.Microsecond);
+#endif
+    }
+
+    [Fact]
+    public void DateTimeNonRfc3339FormatIsRejected()
+    {
+        var json = "{\"metadata\":{\"creationTimestamp\":\"12/31/2023\"}}";
+
+        Assert.Throws<FormatException>(() => KubernetesJson.Deserialize<V1Secret>(json));
+    }
 }