Modified Context in ParseResults to verify that _commands does not co…

…ntain multiple Context or no Context. Doing so will raise a LookupError with a description of the problem. Two test cases are also included in tests/test_kerngen.py to verify that the correct error is raised.

kerngen/high_parser/parser.py

@@ -31,15 +31,32 @@ class ParseResults:
     """Queryable class about parse results"""
 
     def __init__(self, iterable, symbols_map):
-        self._commands = list(iterable)
+        self._commands = ParseResults._validate_commands(list(iterable))
         self._symbols_map = symbols_map
 
+    @staticmethod
+    def _get_context_from_commands_list(commands):
+        """Validates that the commands list contains a single context"""
+        context_list = [context for context in commands if isinstance(context, Context)]
+        if not context_list:
+            raise LookupError("No Context found for commands list for ParseResults")
+        if len(context_list) > 1:
+            raise LookupError(
+                "Multiple Context found in commands list for ParseResults"
+            )
+        return context_list[0]
+
+    @staticmethod
+    def _validate_commands(commands):
+        """Validate commands. Raises a LookupError if context is missing."""
+        ParseResults._get_context_from_commands_list(commands)
+        # Todo: add other checks here
+        return commands
+
     @property
     def context(self):
         """Return found context"""
-        return next(
-            context for context in self._commands if isinstance(context, Context)
-        )
+        return ParseResults._get_context_from_commands_list(self._commands)
 
     @property
     def commands(self):

kerngen/tests/test_kerngen.py

@@ -1,10 +1,15 @@
+# Copyright (C) 2024 Intel Corporation
+# SPDX-License-Identifier: Apache-2.0
+
 # Copyright (C) 2024 Intel Corporation
 
 """Test the expected behaviour of the kerngen script"""
 
 from enum import Enum
 from pathlib import Path
 from subprocess import run
+from high_parser.parser import ParseResults
+from high_parser.types import Context
 import pytest
 
 
@@ -93,6 +98,26 @@ def test_invalid_scheme(kerngen_path):
     assert result.returncode != 0
 
 
+def test_parse_results_missing_context_in_constructor():
+    """Test ParseResults constructor for missing context"""
+    with pytest.raises(LookupError) as e:
+        ParseResults([], {})
+    assert "No Context found for commands list for ParseResults" in str(e.value)
+
+
+def test_parse_results_multiple_context_in_constructor():
+    """Test ParseResults constructor for multiple context"""
+    with pytest.raises(LookupError) as e:
+        ParseResults(
+            [
+                Context(scheme="BGV", poly_order=8192, max_rns=1),
+                Context(scheme="CKKS", poly_order=8192, max_rns=1),
+            ],
+            {},
+        )
+    assert "Multiple Context found in commands list for ParseResults" in str(e.value)
+
+
 @pytest.fixture(name="gen_op_data")
 def fixture_gen_op_data(request):
     """Given an op name, return both the input and expected output strings"""

pytest.ini

@@ -0,0 +1,2 @@
+[pytest]
+pythonpath = kerngen