Add test to check thrift field IDs (#602)

* Add test to check thrift field IDs

---------

Signed-off-by: Vikrant Puppala <vikrant.puppala@databricks.com>

Author: vikrantpuppala

tests/unit/test_thrift_field_ids.py

@@ -0,0 +1,97 @@
+import inspect
+import pytest
+
+from databricks.sql.thrift_api.TCLIService import ttypes
+
+
+class TestThriftFieldIds:
+    """
+    Unit test to validate that all Thrift-generated field IDs comply with the maximum limit.
+
+    Field IDs in Thrift must stay below 3329 to avoid conflicts with reserved ranges
+    and ensure compatibility with various Thrift implementations and protocols.
+    """
+
+    MAX_ALLOWED_FIELD_ID = 3329
+
+    # Known exceptions that exceed the field ID limit
+    KNOWN_EXCEPTIONS = {
+        ('TExecuteStatementReq', 'enforceEmbeddedSchemaCorrectness'): 3353,
+        ('TSessionHandle', 'serverProtocolVersion'): 3329,
+    }
+
+    def test_all_thrift_field_ids_are_within_allowed_range(self):
+        """
+        Validates that all field IDs in Thrift-generated classes are within the allowed range.
+        
+        This test prevents field ID conflicts and ensures compatibility with different
+        Thrift implementations and protocols.
+        """
+        violations = []
+        
+        # Get all classes from the ttypes module
+        for name, obj in inspect.getmembers(ttypes):
+            if (inspect.isclass(obj) and 
+                hasattr(obj, 'thrift_spec') and 
+                obj.thrift_spec is not None):
+                
+                self._check_class_field_ids(obj, name, violations)
+        
+        if violations:
+            error_message = self._build_error_message(violations)
+            pytest.fail(error_message)
+
+    def _check_class_field_ids(self, cls, class_name, violations):
+        """
+        Checks all field IDs in a Thrift class and reports violations.
+        
+        Args:
+            cls: The Thrift class to check
+            class_name: Name of the class for error reporting
+            violations: List to append violation messages to
+        """
+        thrift_spec = cls.thrift_spec
+        
+        if not isinstance(thrift_spec, (tuple, list)):
+            return
+            
+        for spec_entry in thrift_spec:
+            if spec_entry is None:
+                continue
+                
+            # Thrift spec format: (field_id, field_type, field_name, ...)
+            if isinstance(spec_entry, (tuple, list)) and len(spec_entry) >= 3:
+                field_id = spec_entry[0]
+                field_name = spec_entry[2]
+                
+                # Skip known exceptions
+                if (class_name, field_name) in self.KNOWN_EXCEPTIONS:
+                    continue
+                
+                if isinstance(field_id, int) and field_id >= self.MAX_ALLOWED_FIELD_ID:
+                    violations.append(
+                        "{} field '{}' has field ID {} (exceeds maximum of {})".format(
+                            class_name, field_name, field_id, self.MAX_ALLOWED_FIELD_ID - 1
+                        )
+                    )
+
+    def _build_error_message(self, violations):
+        """
+        Builds a comprehensive error message for field ID violations.
+        
+        Args:
+            violations: List of violation messages
+            
+        Returns:
+            Formatted error message
+        """
+        error_message = (
+            "Found Thrift field IDs that exceed the maximum allowed value of {}.\n"
+            "This can cause compatibility issues and conflicts with reserved ID ranges.\n"
+            "Violations found:\n".format(self.MAX_ALLOWED_FIELD_ID - 1)
+        )
+        
+        for violation in violations:
+            error_message += "  - {}\n".format(violation)
+            
+        return error_message