test(batch): verify tags serialize in batch payloads

src/main/java/com/resend/services/batch/Batch.java

@@ -33,6 +33,8 @@ public Batch(final String apiKey) {
     /**
      * Sends up to 100 batch emails.
      *
+     * <p>Each email supports standard send options plus {@code tags}.
+     *
      * @param emails batch emails to send.
      * @return The emails ids.
      * @throws ResendException If an error occurs while sending batch emails.
@@ -54,6 +56,8 @@ public CreateBatchEmailsResponse send(List<CreateEmailOptions> emails) throws Re
     /**
      * Sends up to 100 batch emails.
      *
+     * <p>Each email supports standard send options plus {@code tags}.
+     *
      * @param emails batch emails to send.
      * @param requestOptions The options with additional headers.
      * @return The emails ids.

src/test/java/com/resend/services/batch/BatchTest.java

@@ -12,6 +12,7 @@
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
+import org.mockito.ArgumentCaptor;
 import org.mockito.Mock;
 import org.mockito.MockitoAnnotations;
 
@@ -50,6 +51,21 @@ public void tearDown() throws Exception {
         mocks.close();
     }
 
+    @Test
+    public void testCreateBatchEmails_SerializesTags() throws ResendException {
+        List<CreateEmailOptions> batchEmailsRequest = EmailsUtil.createBatchEmailOptions();
+        ArgumentCaptor<String> payloadCaptor = ArgumentCaptor.forClass(String.class);
+        AbstractHttpResponse<String> httpResponse = new AbstractHttpResponse<>(200, BATCH_RESPONSE_JSON, true);
+
+        when(httpClient.perform(eq("/emails/batch"), anyString(), eq(HttpMethod.POST), payloadCaptor.capture(), any(MediaType.class)))
+                .thenReturn(httpResponse);
+
+        batch.send(batchEmailsRequest);
+
+        String payload = payloadCaptor.getValue();
+        assertTrue(payload.contains("\"tags\":[{\"name\":\"tagName\",\"value\":\"tagValue\"}]"));
+    }
+
     @Test
     public void testCreateBatchEmails_Success() throws ResendException {
         List<CreateEmailOptions> batchEmailsRequest = EmailsUtil.createBatchEmailOptions();

src/test/java/com/resend/services/util/EmailsUtil.java

@@ -99,8 +99,21 @@ public static CancelEmailResponse cancelEmailResponse() {
         return new CancelEmailResponse("123", "emails");
     }
 
+    public static CreateEmailOptions createBatchEmailOption() {
+        return CreateEmailOptions.builder()
+                .from("Acme <onboarding@resend.dev>")
+                .to(Arrays.asList("example@resend.dev"))
+                .cc(Arrays.asList("example@resend.dev"))
+                .bcc(Arrays.asList("example@resend.dev"))
+                .replyTo(Arrays.asList("example@resend.dev", "example@resend.dev"))
+                .text("Hello, this is a batch email.")
+                .subject("Test batch email with tags")
+                .tags(Arrays.asList(createTag()))
+                .build();
+    }
+
     public static List<CreateEmailOptions> createBatchEmailOptions() {
-        return Arrays.asList(createEmailOptions(), createEmailOptions());
+        return Arrays.asList(createBatchEmailOption(), createBatchEmailOption());
     }
 
     public static CreateBatchEmailsResponse createBatchEmailsResponse() {