!8754 Fix test team issues for python API

From: @alex-yuyue
Reviewed-by: 
Signed-off-by:

mindspore/ccsrc/minddata/dataset/engine/datasetops/dataset_op.cc

@@ -313,7 +313,7 @@ Status DatasetOp::GetNumClasses(int64_t *num_classes) {
     return child_[0]->GetNumClasses(num_classes);
   } else {
     *num_classes = -1;
-    RETURN_STATUS_UNEXPECTED("Can't get the number of classes for the current tree.");
+    return Status::OK();
   }
 }
 

mindspore/ccsrc/minddata/dataset/engine/ir/datasetops/dataset_node.cc

@@ -173,11 +173,15 @@ Status ValidateDatasetColumnParam(const std::string &dataset_name, const std::st
       RETURN_STATUS_SYNTAX_ERROR(err_msg);
     }
   }
-  std::set<std::string> columns_set(columns.begin(), columns.end());
-  if (columns_set.size() != columns.size()) {
-    std::string err_msg = dataset_name + ":" + column_param + ": Every column name should not be same with others";
-    MS_LOG(ERROR) << err_msg;
-    RETURN_STATUS_SYNTAX_ERROR(err_msg);
+  std::set<std::string> columns_set;
+  for (auto &column_name : columns) {
+    auto result = columns_set.insert(column_name);
+    if (result.second == false) {
+      std::string err_msg = dataset_name + ":" + column_param +
+                            ": Invalid parameter, duplicate column names are not allowed: " + *result.first;
+      MS_LOG(ERROR) << err_msg;
+      RETURN_STATUS_SYNTAX_ERROR(err_msg);
+    }
   }
   return Status::OK();
 }

mindspore/ccsrc/minddata/dataset/engine/ir/datasetops/dataset_node.h

@@ -128,7 +128,6 @@ class DatasetNode : public std::enable_shared_from_this<DatasetNode> {
 
  protected:
   std::vector<std::shared_ptr<DatasetNode>> children;
-  std::shared_ptr<DatasetNode> parent;
   std::shared_ptr<DatasetCache> cache_;
   Status AddCacheOp(std::vector<std::shared_ptr<DatasetOp>> *node_ops);
 

mindspore/ccsrc/minddata/dataset/engine/ir/datasetops/sync_wait_node.cc

@@ -50,12 +50,6 @@ Status SyncWaitNode::ValidateParams() {
     RETURN_STATUS_SYNTAX_ERROR(err_msg);
   }
 
-  if (condition_name_.empty()) {
-    std::string err_msg = "SyncWaitNode: condition_name must not be empty.";
-    MS_LOG(ERROR) << err_msg;
-    RETURN_STATUS_SYNTAX_ERROR(err_msg);
-  }
-
   return Status::OK();
 }