Vasant K. Prabhu

"""Unit tests for bninja/analysis/scores.py — ObfuscationScores."""
import sys
import pytest
from unittest.mock import MagicMock

# Install binaryninja stubs before importing
from tests.unit.conftest_binja_stubs import (
    install_binja_stubs,
    HighLevelILOperation,
)
bn_mock = install_binja_stubs()

from redb.extractors.decompiler.bninja.analysis.scores import (
    ObfuscationScores,
    get_dominated_by,
    uses_mba,
)
import binaryninja.highlevelil as hlil_mod


# ============================================================================
# Helper: Mock HLIL instruction
# ============================================================================

class MockHLILInstruction(hlil_mod.HighLevelILInstruction):
    """Mock HLIL instruction with operation and operands."""
    def __init__(self, operation, operands=None):
        self.operation = operation
        self.operands = operands or []


class MockHLILBasicBlock:
    """Mock HLIL basic block for flattened score testing."""
    def __init__(self, incoming_edges=None, dominator_tree_children=None):
        self.incoming_edges = incoming_edges or []
        self.dominator_tree_children = dominator_tree_children or []


# ============================================================================
# 5a. ObfuscationScores
# ============================================================================


class TestFlattenedScore:
    def test_flattened_score_no_back_edges(self):
        """Linear CFG with no back edges -> score 0.0."""
        block = MockHLILBasicBlock(incoming_edges=[], dominator_tree_children=[])
        func = MagicMock()
        func.basic_blocks = [block]
        scores = ObfuscationScores(func)
        assert scores.flattened_score() == 0.0

    def test_flattened_score_with_loop(self):
        """CFG with a back edge -> score > 0.0."""
        block = MockHLILBasicBlock(dominator_tree_children=[])
        # Create a back edge: an incoming edge whose source is in the dominated set
        edge = MagicMock()
        edge.source = block  # source IS the dominator -> back edge
        block.incoming_edges = [edge]
        func = MagicMock()
        func.basic_blocks = [block]
        scores = ObfuscationScores(func)
        assert scores.flattened_score() > 0.0

    def test_flattened_score_fully_flat(self):
        """Flattened CFG: one block dominates all -> ratio close to 1.0."""
        children = [MockHLILBasicBlock() for _ in range(4)]
        root = MockHLILBasicBlock(dominator_tree_children=children)
        # Back edge from root incoming
        edge = MagicMock()
        edge.source = root
        root.incoming_edges = [edge]
        all_blocks = [root] + children
        func = MagicMock()
        func.basic_blocks = all_blocks
        scores = ObfuscationScores(func)
        assert scores.flattened_score() == pytest.approx(1.0)


class TestMBAScore:
    def test_mba_score_no_mixed_ops(self):
        """Instructions with only arithmetic -> score 0.0."""
        instr = MockHLILInstruction(HighLevelILOperation.HLIL_ADD, operands=[])
        func = MagicMock()
        func.instructions = [instr]
        scores = ObfuscationScores(func)
        assert scores.MBA_score() == 0.0

    def test_mba_score_mixed_ops(self):
        """Instructions with arithmetic + logic -> score > 0.0."""
        inner_logic = MockHLILInstruction(HighLevelILOperation.HLIL_XOR, operands=[])
        outer_arith = MockHLILInstruction(
            HighLevelILOperation.HLIL_ADD, operands=[inner_logic]
        )
        func = MagicMock()
        func.instructions = [outer_arith]
        scores = ObfuscationScores(func)
        assert scores.MBA_score() > 0.0

    def test_mba_score_all_mixed(self):
        """Every instruction has both -> score 1.0."""
        inner_logic = MockHLILInstruction(HighLevelILOperation.HLIL_NOT, operands=[])
        outer_arith = MockHLILInstruction(
            HighLevelILOperation.HLIL_SUB, operands=[inner_logic]
        )
        func = MagicMock()
        func.instructions = [outer_arith]
        scores = ObfuscationScores(func)
        assert scores.MBA_score() == 1.0


class TestGetDominatedBy:
    def test_get_dominated_by(self):
        child1 = MockHLILBasicBlock(dominator_tree_children=[])
        child2 = MockHLILBasicBlock(dominator_tree_children=[])
        root = MockHLILBasicBlock(dominator_tree_children=[child1, child2])
        result = get_dominated_by(root)
        assert root in result
        assert child1 in result
        assert child2 in result
        assert len(result) == 3


class TestUsesMBA:
    def test_uses_mba_arithmetic_only(self):
        instr = MockHLILInstruction(HighLevelILOperation.HLIL_ADD, operands=[])
        assert uses_mba(instr) is False

    def test_uses_mba_logic_only(self):
        instr = MockHLILInstruction(HighLevelILOperation.HLIL_XOR, operands=[])
        assert uses_mba(instr) is False

    def test_uses_mba_mixed(self):
        inner = MockHLILInstruction(HighLevelILOperation.HLIL_AND, operands=[])
        outer = MockHLILInstruction(HighLevelILOperation.HLIL_ADD, operands=[inner])
        assert uses_mba(outer) is True