Fix #1135: Connect PythonASTAnalyzer to the analysis pipeline

[anushkagupta200615-jpg]

Description

This PR modifies backend/app/services/ast_analyzer.py to correctly call analyze_python_ast(source) within the main analyze() function. Previously, the PythonASTAnalyzer class was instantiated but never executed, skipping vital checks for mutable default arguments, bare except: blocks, eval/exec usage, and builtin variable shadowing.

By appending the results of analyze_python_ast(source) to the issues list, these AST-based checks are now successfully integrated into the analysis pipeline.

Related Issue

Fixes #1135

Type of change

• Bug fix
• New feature / enhancement
• Documentation update
• Test addition
• Refactor

Checklist

• I have read CONTRIBUTING.md
• My branch is up to date with main
• I have run pytest -v and all tests pass (for ast_analyzer.py)
• I have not introduced duplicate issues or features
• My PR title follows the format: feat/fix/docs/test: short description
• I have added tests for new features (Level 2 and 3 issues)
• No hardcoded secrets or API keys in my code
• This PR is linked to a GSSoC 2026 issue

Screenshots (if frontend change)

N/A

Test evidence

$ pytest backend/tests/test_ast_analyzer.py -v
============================= test session starts =============================
platform win32 -- Python 3.10.0, pytest-9.1.1, pluggy-1.6.0
collected 40 items

backend/tests/test_ast_analyzer.py::test_mutable_default_list PASSED     [  2%]
backend/tests/test_ast_analyzer.py::test_mutable_default_dict PASSED     [  5%]
backend/tests/test_ast_analyzer.py::test_mutable_default_set PASSED      [  7%]
backend/tests/test_ast_analyzer.py::test_no_mutable_default_with_none PASSED [ 10%]
backend/tests/test_ast_analyzer.py::test_no_mutable_default_immutable PASSED [ 12%]
backend/tests/test_ast_analyzer.py::test_bare_except_detected PASSED     [ 15%]
backend/tests/test_ast_analyzer.py::test_bare_except_line_number PASSED  [ 17%]
backend/tests/test_ast_analyzer.py::test_specific_except_not_flagged PASSED [ 20%]
backend/tests/test_ast_analyzer.py::test_except_exception_not_flagged PASSED [ 22%]
backend/tests/test_ast_analyzer.py::test_eval_detected PASSED            [ 25%]
backend/tests/test_ast_analyzer.py::test_exec_detected PASSED            [ 27%]
backend/tests/test_ast_analyzer.py::test_eval_line_number PASSED         [ 30%]
backend/tests/test_ast_analyzer.py::test_eval_severity_is_error PASSED   [ 32%]
backend/tests/test_ast_analyzer.py::test_no_false_positive_ast_literal_eval PASSED [ 35%]
backend/tests/test_ast_analyzer.py::test_shadow_list PASSED              [ 37%]
backend/tests/test_ast_analyzer.py::test_shadow_id PASSED                [ 40%]
backend/tests/test_ast_analyzer.py::test_shadow_len PASSED               [ 42%]
backend/tests/test_ast_analyzer.py::test_shadow_print PASSED             [ 45%]
backend/tests/test_ast_analyzer.py::test_no_shadow_for_user_names PASSED [ 47%]
backend/tests/test_ast_analyzer.py::test_unreachable_after_return PASSED [ 50%]
backend/tests/test_ast_analyzer.py::test_unreachable_after_raise PASSED  [ 52%]
backend/tests/test_ast_analyzer.py::test_reachable_code_not_flagged PASSED [ 55%]
backend/tests/test_ast_analyzer.py::test_unreachable_line_number PASSED  [ 57%]
backend/tests/test_ast_analyzer.py::test_syntax_error_returns_issue PASSED [ 60%]
backend/tests/test_ast_analyzer.py::test_syntax_error_severity PASSED    [ 62%]
backend/tests/test_ast_analyzer.py::test_syntax_error_does_not_crash PASSED [ 65%]
backend/tests/test_ast_analyzer.py::test_clean_code_returns_no_ast_issues PASSED [ 67%]
backend/tests/test_ast_analyzer.py::test_issue_shape_has_required_fields PASSED [ 70%]
backend/tests/test_ast_analyzer.py::test_unreachable_code PASSED         [ 72%]
backend/tests/test_ast_analyzer.py::test_unused_import PASSED            [ 75%]
backend/tests/test_ast_analyzer.py::test_unused_argument PASSED          [ 77%]
backend/tests/test_ast_analyzer.py::test_clean_code_no_false_positives PASSED [ 80%]
backend/tests/test_ast_analyzer.py::test_correct_line_number_unreachable PASSED [ 82%]
backend/tests/test_ast_analyzer.py::test_self_not_flagged_as_unused PASSED [ 85%]
backend/tests/test_ast_analyzer.py::test_underscore_param_not_flagged PASSED [ 87%]
backend/tests/test_ast_analyzer.py::test_used_alias_not_flagged PASSED   [ 90%]
backend/tests/test_ast_analyzer.py::test_too_many_returns_exact_boundary PASSED [ 92%]
backend/tests/test_ast_analyzer.py::test_unreachable_only_flags_after_not_before PASSED [ 95%]
backend/tests/test_ast_analyzer.py::test_nested_function_returns_not_counted_in_outer PASSED [ 97%]
backend/tests/test_ast_analyzer.py::test_deep_nesting_exact_boundary PASSED [100%]

============================= 40 passed in 0.15s ==============================