feat(context): implement token budget management (Phase 2)
Add TokenCalculator with LLM Gateway integration for accurate token counting with in-memory caching and fallback character-based estimation. Implement TokenBudget for tracking allocations per context type with budget enforcement, and BudgetAllocator for creating budgets based on model context window sizes. - TokenCalculator: MCP integration, caching, model-specific ratios - TokenBudget: allocation tracking, can_fit/allocate/deallocate/reset - BudgetAllocator: model context sizes, budget creation and adjustment - 35 comprehensive tests covering all budget functionality Part of #61 - Context Management Engine 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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backend/tests/services/context/test_budget.py
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533
backend/tests/services/context/test_budget.py
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"""Tests for token budget management."""
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from unittest.mock import AsyncMock, MagicMock
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import pytest
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from app.services.context.budget import (
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BudgetAllocator,
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TokenBudget,
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TokenCalculator,
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)
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from app.services.context.config import ContextSettings
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from app.services.context.exceptions import BudgetExceededError
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from app.services.context.types import ContextType
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class TestTokenBudget:
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"""Tests for TokenBudget dataclass."""
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def test_creation(self) -> None:
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"""Test basic budget creation."""
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budget = TokenBudget(total=10000)
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assert budget.total == 10000
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assert budget.system == 0
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assert budget.total_used() == 0
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def test_creation_with_allocations(self) -> None:
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"""Test budget creation with allocations."""
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budget = TokenBudget(
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total=10000,
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system=500,
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task=1000,
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knowledge=4000,
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conversation=2000,
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tools=500,
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response_reserve=1500,
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buffer=500,
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)
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assert budget.system == 500
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assert budget.knowledge == 4000
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assert budget.response_reserve == 1500
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def test_get_allocation(self) -> None:
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"""Test getting allocation for a type."""
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budget = TokenBudget(
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total=10000,
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system=500,
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knowledge=4000,
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)
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assert budget.get_allocation(ContextType.SYSTEM) == 500
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assert budget.get_allocation(ContextType.KNOWLEDGE) == 4000
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assert budget.get_allocation("system") == 500
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def test_remaining(self) -> None:
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"""Test remaining budget calculation."""
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budget = TokenBudget(
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total=10000,
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system=500,
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knowledge=4000,
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)
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# Initially full
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assert budget.remaining(ContextType.SYSTEM) == 500
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assert budget.remaining(ContextType.KNOWLEDGE) == 4000
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# After allocation
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budget.allocate(ContextType.SYSTEM, 200)
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assert budget.remaining(ContextType.SYSTEM) == 300
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def test_can_fit(self) -> None:
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"""Test can_fit check."""
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budget = TokenBudget(
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total=10000,
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system=500,
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knowledge=4000,
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)
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assert budget.can_fit(ContextType.SYSTEM, 500) is True
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assert budget.can_fit(ContextType.SYSTEM, 501) is False
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assert budget.can_fit(ContextType.KNOWLEDGE, 4000) is True
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def test_allocate_success(self) -> None:
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"""Test successful allocation."""
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budget = TokenBudget(
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total=10000,
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system=500,
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)
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result = budget.allocate(ContextType.SYSTEM, 200)
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assert result is True
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assert budget.get_used(ContextType.SYSTEM) == 200
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assert budget.remaining(ContextType.SYSTEM) == 300
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def test_allocate_exceeds_budget(self) -> None:
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"""Test allocation exceeding budget."""
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budget = TokenBudget(
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total=10000,
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system=500,
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)
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with pytest.raises(BudgetExceededError) as exc_info:
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budget.allocate(ContextType.SYSTEM, 600)
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assert exc_info.value.allocated == 500
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assert exc_info.value.requested == 600
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def test_allocate_force(self) -> None:
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"""Test forced allocation exceeding budget."""
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budget = TokenBudget(
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total=10000,
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system=500,
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)
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# Force should allow exceeding
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result = budget.allocate(ContextType.SYSTEM, 600, force=True)
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assert result is True
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assert budget.get_used(ContextType.SYSTEM) == 600
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def test_deallocate(self) -> None:
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"""Test deallocation."""
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budget = TokenBudget(
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total=10000,
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system=500,
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)
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budget.allocate(ContextType.SYSTEM, 300)
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assert budget.get_used(ContextType.SYSTEM) == 300
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budget.deallocate(ContextType.SYSTEM, 100)
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assert budget.get_used(ContextType.SYSTEM) == 200
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def test_deallocate_below_zero(self) -> None:
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"""Test deallocation doesn't go below zero."""
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budget = TokenBudget(
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total=10000,
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system=500,
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)
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budget.allocate(ContextType.SYSTEM, 100)
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budget.deallocate(ContextType.SYSTEM, 200)
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assert budget.get_used(ContextType.SYSTEM) == 0
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def test_total_remaining(self) -> None:
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"""Test total remaining calculation."""
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budget = TokenBudget(
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total=10000,
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system=500,
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knowledge=4000,
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response_reserve=1500,
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buffer=500,
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)
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# Usable = total - response_reserve - buffer = 10000 - 1500 - 500 = 8000
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assert budget.total_remaining() == 8000
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# After allocation
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budget.allocate(ContextType.SYSTEM, 200)
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assert budget.total_remaining() == 7800
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def test_utilization(self) -> None:
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"""Test utilization calculation."""
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budget = TokenBudget(
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total=10000,
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system=500,
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response_reserve=1500,
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buffer=500,
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)
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# No usage = 0%
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assert budget.utilization(ContextType.SYSTEM) == 0.0
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# Half used = 50%
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budget.allocate(ContextType.SYSTEM, 250)
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assert budget.utilization(ContextType.SYSTEM) == 0.5
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# Total utilization
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assert budget.utilization() == 250 / 8000 # 250 / (10000 - 1500 - 500)
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def test_reset(self) -> None:
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"""Test reset clears usage."""
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budget = TokenBudget(
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total=10000,
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system=500,
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)
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budget.allocate(ContextType.SYSTEM, 300)
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assert budget.get_used(ContextType.SYSTEM) == 300
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budget.reset()
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assert budget.get_used(ContextType.SYSTEM) == 0
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assert budget.total_used() == 0
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def test_to_dict(self) -> None:
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"""Test to_dict conversion."""
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budget = TokenBudget(
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total=10000,
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system=500,
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task=1000,
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knowledge=4000,
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)
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budget.allocate(ContextType.SYSTEM, 200)
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data = budget.to_dict()
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assert data["total"] == 10000
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assert data["allocations"]["system"] == 500
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assert data["used"]["system"] == 200
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assert data["remaining"]["system"] == 300
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class TestBudgetAllocator:
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"""Tests for BudgetAllocator."""
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def test_create_budget(self) -> None:
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"""Test budget creation with default allocations."""
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allocator = BudgetAllocator()
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budget = allocator.create_budget(100000)
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assert budget.total == 100000
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assert budget.system == 5000 # 5%
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assert budget.task == 10000 # 10%
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assert budget.knowledge == 40000 # 40%
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assert budget.conversation == 20000 # 20%
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assert budget.tools == 5000 # 5%
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assert budget.response_reserve == 15000 # 15%
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assert budget.buffer == 5000 # 5%
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def test_create_budget_custom_allocations(self) -> None:
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"""Test budget creation with custom allocations."""
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allocator = BudgetAllocator()
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budget = allocator.create_budget(
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100000,
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custom_allocations={
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"system": 0.10,
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"task": 0.10,
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"knowledge": 0.30,
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"conversation": 0.25,
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"tools": 0.05,
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"response": 0.15,
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"buffer": 0.05,
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},
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)
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assert budget.system == 10000 # 10%
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assert budget.knowledge == 30000 # 30%
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def test_create_budget_for_model(self) -> None:
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"""Test budget creation for specific model."""
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allocator = BudgetAllocator()
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# Claude models have 200k context
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budget = allocator.create_budget_for_model("claude-3-sonnet")
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assert budget.total == 200000
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# GPT-4 has 8k context
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budget = allocator.create_budget_for_model("gpt-4")
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assert budget.total == 8192
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# GPT-4-turbo has 128k context
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budget = allocator.create_budget_for_model("gpt-4-turbo")
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assert budget.total == 128000
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def test_get_model_context_size(self) -> None:
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"""Test model context size lookup."""
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allocator = BudgetAllocator()
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# Known models
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assert allocator.get_model_context_size("claude-3-opus") == 200000
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assert allocator.get_model_context_size("gpt-4") == 8192
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assert allocator.get_model_context_size("gemini-1.5-pro") == 2000000
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# Unknown model gets default
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assert allocator.get_model_context_size("unknown-model") == 8192
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def test_adjust_budget(self) -> None:
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"""Test budget adjustment."""
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allocator = BudgetAllocator()
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budget = allocator.create_budget(10000)
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original_system = budget.system
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original_buffer = budget.buffer
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# Increase system by taking from buffer
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budget = allocator.adjust_budget(budget, ContextType.SYSTEM, 200)
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assert budget.system == original_system + 200
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assert budget.buffer == original_buffer - 200
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def test_adjust_budget_limited_by_buffer(self) -> None:
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"""Test that adjustment is limited by buffer size."""
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allocator = BudgetAllocator()
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budget = allocator.create_budget(10000)
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original_buffer = budget.buffer
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# Try to increase more than buffer allows
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budget = allocator.adjust_budget(budget, ContextType.SYSTEM, 10000)
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# Should only increase by buffer amount
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assert budget.buffer == 0
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assert budget.system <= original_buffer + budget.system
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def test_rebalance_budget(self) -> None:
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"""Test budget rebalancing."""
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allocator = BudgetAllocator()
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budget = allocator.create_budget(10000)
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# Use most of knowledge budget
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budget.allocate(ContextType.KNOWLEDGE, 3500)
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# Rebalance prioritizing knowledge
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budget = allocator.rebalance_budget(
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budget,
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prioritize=[ContextType.KNOWLEDGE],
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)
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# Knowledge should have gotten more tokens
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# (This is a fuzzy test - just check it runs)
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assert budget is not None
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class TestTokenCalculator:
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"""Tests for TokenCalculator."""
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def test_estimate_tokens(self) -> None:
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"""Test token estimation."""
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calc = TokenCalculator()
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# Empty string
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assert calc.estimate_tokens("") == 0
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# Short text (~4 chars per token)
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text = "This is a test message"
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estimate = calc.estimate_tokens(text)
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assert 4 <= estimate <= 8
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def test_estimate_tokens_model_specific(self) -> None:
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"""Test model-specific estimation ratios."""
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calc = TokenCalculator()
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text = "a" * 100
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# Claude uses 3.5 chars per token
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claude_estimate = calc.estimate_tokens(text, "claude-3-sonnet")
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# GPT uses 4.0 chars per token
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gpt_estimate = calc.estimate_tokens(text, "gpt-4")
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# Claude should estimate more tokens (smaller ratio)
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assert claude_estimate >= gpt_estimate
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@pytest.mark.asyncio
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async def test_count_tokens_no_mcp(self) -> None:
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"""Test token counting without MCP (fallback to estimation)."""
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calc = TokenCalculator()
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text = "This is a test"
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count = await calc.count_tokens(text)
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# Should use estimation
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assert count > 0
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@pytest.mark.asyncio
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async def test_count_tokens_with_mcp_success(self) -> None:
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"""Test token counting with MCP integration."""
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# Mock MCP manager
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mock_mcp = MagicMock()
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mock_result = MagicMock()
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mock_result.success = True
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mock_result.data = {"token_count": 42}
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mock_mcp.call_tool = AsyncMock(return_value=mock_result)
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calc = TokenCalculator(mcp_manager=mock_mcp)
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count = await calc.count_tokens("test text")
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assert count == 42
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mock_mcp.call_tool.assert_called_once()
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@pytest.mark.asyncio
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async def test_count_tokens_with_mcp_failure(self) -> None:
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"""Test fallback when MCP fails."""
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# Mock MCP manager that fails
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mock_mcp = MagicMock()
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mock_mcp.call_tool = AsyncMock(side_effect=Exception("Connection failed"))
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calc = TokenCalculator(mcp_manager=mock_mcp)
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count = await calc.count_tokens("test text")
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# Should fall back to estimation
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assert count > 0
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@pytest.mark.asyncio
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async def test_count_tokens_caching(self) -> None:
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"""Test that token counts are cached."""
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mock_mcp = MagicMock()
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mock_result = MagicMock()
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mock_result.success = True
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mock_result.data = {"token_count": 42}
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mock_mcp.call_tool = AsyncMock(return_value=mock_result)
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calc = TokenCalculator(mcp_manager=mock_mcp)
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# First call
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count1 = await calc.count_tokens("test text")
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# Second call (should use cache)
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count2 = await calc.count_tokens("test text")
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assert count1 == count2 == 42
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# MCP should only be called once
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assert mock_mcp.call_tool.call_count == 1
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@pytest.mark.asyncio
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async def test_count_tokens_batch(self) -> None:
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"""Test batch token counting."""
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calc = TokenCalculator()
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texts = ["Hello", "World", "Test message here"]
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counts = await calc.count_tokens_batch(texts)
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assert len(counts) == 3
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assert all(c > 0 for c in counts)
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def test_cache_stats(self) -> None:
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"""Test cache statistics."""
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calc = TokenCalculator()
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stats = calc.get_cache_stats()
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assert stats["enabled"] is True
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assert stats["size"] == 0
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assert stats["hits"] == 0
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assert stats["misses"] == 0
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@pytest.mark.asyncio
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async def test_cache_hit_rate(self) -> None:
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"""Test cache hit rate tracking."""
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calc = TokenCalculator()
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# Make some calls
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await calc.count_tokens("text1")
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await calc.count_tokens("text2")
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await calc.count_tokens("text1") # Cache hit
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stats = calc.get_cache_stats()
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assert stats["hits"] == 1
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assert stats["misses"] == 2
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def test_clear_cache(self) -> None:
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"""Test cache clearing."""
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calc = TokenCalculator()
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calc._cache["test"] = 100
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calc._cache_hits = 5
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calc.clear_cache()
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assert len(calc._cache) == 0
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assert calc._cache_hits == 0
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def test_set_mcp_manager(self) -> None:
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"""Test setting MCP manager after initialization."""
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calc = TokenCalculator()
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assert calc._mcp is None
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mock_mcp = MagicMock()
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calc.set_mcp_manager(mock_mcp)
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assert calc._mcp is mock_mcp
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@pytest.mark.asyncio
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async def test_parse_token_count_formats(self) -> None:
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"""Test parsing different token count response formats."""
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calc = TokenCalculator()
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# Dict with token_count
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assert calc._parse_token_count({"token_count": 42}) == 42
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# Dict with tokens
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assert calc._parse_token_count({"tokens": 42}) == 42
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# Dict with count
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assert calc._parse_token_count({"count": 42}) == 42
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# Direct int
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assert calc._parse_token_count(42) == 42
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# JSON string
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assert calc._parse_token_count('{"token_count": 42}') == 42
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# Invalid
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assert calc._parse_token_count("invalid") is None
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class TestBudgetIntegration:
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"""Integration tests for budget management."""
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@pytest.mark.asyncio
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async def test_full_budget_workflow(self) -> None:
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"""Test complete budget allocation workflow."""
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# Create settings and allocator
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settings = ContextSettings()
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allocator = BudgetAllocator(settings)
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# Create budget for Claude
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budget = allocator.create_budget_for_model("claude-3-sonnet")
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assert budget.total == 200000
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# Create calculator (without MCP for test)
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calc = TokenCalculator()
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# Simulate context allocation
|
||||
system_text = "You are a helpful assistant." * 10
|
||||
system_tokens = await calc.count_tokens(system_text)
|
||||
|
||||
# Allocate
|
||||
assert budget.can_fit(ContextType.SYSTEM, system_tokens)
|
||||
budget.allocate(ContextType.SYSTEM, system_tokens)
|
||||
|
||||
# Check state
|
||||
assert budget.get_used(ContextType.SYSTEM) == system_tokens
|
||||
assert budget.remaining(ContextType.SYSTEM) == budget.system - system_tokens
|
||||
|
||||
@pytest.mark.asyncio
|
||||
async def test_budget_overflow_handling(self) -> None:
|
||||
"""Test handling budget overflow."""
|
||||
allocator = BudgetAllocator()
|
||||
budget = allocator.create_budget(1000) # Small budget
|
||||
|
||||
# Try to allocate more than available
|
||||
with pytest.raises(BudgetExceededError):
|
||||
budget.allocate(ContextType.KNOWLEDGE, 500)
|
||||
|
||||
# Force allocation should work
|
||||
budget.allocate(ContextType.KNOWLEDGE, 500, force=True)
|
||||
assert budget.get_used(ContextType.KNOWLEDGE) == 500
|
||||
Reference in New Issue
Block a user