添加表单字段参数验证和测试

Co-authored-by: binarywang <1343140+binarywang@users.noreply.github.com>

Author: Copilot

weixin-java-common/src/main/java/me/chanjar/weixin/common/bean/CommonUploadParam.java

@@ -75,6 +75,12 @@ public static CommonUploadParam fromBytes(String name, @Nullable String fileName
    * @return 当前对象，支持链式调用
    */
   public CommonUploadParam addFormField(String fieldName, String fieldValue) {
+    if (fieldName == null || fieldName.trim().isEmpty()) {
+      throw new IllegalArgumentException("表单字段名不能为空");
+    }
+    if (fieldValue == null) {
+      throw new IllegalArgumentException("表单字段值不能为null");
+    }
     if (this.formFields == null) {
       this.formFields = new HashMap<>();
     }

weixin-java-common/src/test/java/me/chanjar/weixin/common/bean/CommonUploadParamTest.java

@@ -95,4 +95,25 @@ public void testToString() {
     Assert.assertTrue(str.contains("name:media"));
     Assert.assertTrue(str.contains("formFields:"));
   }
+
+  @Test(expectedExceptions = IllegalArgumentException.class)
+  public void testAddFormFieldWithNullFieldName() {
+    File file = new File("test.txt");
+    CommonUploadParam param = CommonUploadParam.fromFile("media", file);
+    param.addFormField(null, "value");
+  }
+
+  @Test(expectedExceptions = IllegalArgumentException.class)
+  public void testAddFormFieldWithEmptyFieldName() {
+    File file = new File("test.txt");
+    CommonUploadParam param = CommonUploadParam.fromFile("media", file);
+    param.addFormField("", "value");
+  }
+
+  @Test(expectedExceptions = IllegalArgumentException.class)
+  public void testAddFormFieldWithNullFieldValue() {
+    File file = new File("test.txt");
+    CommonUploadParam param = CommonUploadParam.fromFile("media", file);
+    param.addFormField("fieldName", null);
+  }
 }