Add unit tests for MTP module

Add 28 unit tests covering:
- Weight extraction from layer 61
- MTPModule forward pass and initialization
- MTPTransformerBlock
- Weight loading into MTPModule
- Sanitize patching and restoration
- Model ID detection for DeepSeek V3/R1
- Parameter flattening utility
- ModelWithHiddenStates wrapper
- KV cache quantization logic
- Speculative decoding acceptance/rejection logic
- MTPGenerationResponse dataclass
- Integration test with mock model

Co-Authored-By: Claude Opus 4.5 <[email protected]>
This commit is contained in:
Alex Cheema
2026-01-22 01:53:04 +00:00
co-authored by Claude Opus 4.5
parent 33bacfa7d8
commit b394a1b665
4 changed files with 667 additions and 0 deletions
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"""Tests for MTP module."""
@@ -0,0 +1,412 @@
"""Unit tests for MTP module components."""
import mlx.core as mx
import mlx.nn as nn
import pytest
from exo.worker.engines.mlx.mtp.module import (
MTP_LAYER_INDEX,
MTPModule,
MTPTransformerBlock,
extract_mtp_weights,
load_mtp_weights_into_module,
)
class MockModelArgs:
"""Mock ModelArgs for testing without importing deepseek_v3."""
def __init__(
self,
hidden_size: int = 256,
intermediate_size: int = 512,
num_attention_heads: int = 4,
num_key_value_heads: int = 4,
rms_norm_eps: float = 1e-6,
vocab_size: int = 1000,
q_lora_rank: int | None = None,
kv_lora_rank: int = 64,
qk_rope_head_dim: int = 16,
v_head_dim: int = 32,
qk_nope_head_dim: int = 32,
rope_theta: float = 10000.0,
rope_scaling: dict | None = None,
attention_bias: bool = False,
max_position_embeddings: int = 2048,
):
self.hidden_size = hidden_size
self.intermediate_size = intermediate_size
self.num_attention_heads = num_attention_heads
self.num_key_value_heads = num_key_value_heads
self.rms_norm_eps = rms_norm_eps
self.vocab_size = vocab_size
self.q_lora_rank = q_lora_rank
self.kv_lora_rank = kv_lora_rank
self.qk_rope_head_dim = qk_rope_head_dim
self.v_head_dim = v_head_dim
self.qk_nope_head_dim = qk_nope_head_dim
self.rope_theta = rope_theta
self.rope_scaling = rope_scaling
self.attention_bias = attention_bias
self.max_position_embeddings = max_position_embeddings
class TestExtractMTPWeights:
"""Tests for extract_mtp_weights function."""
def test_extracts_layer_61_weights(self) -> None:
"""Should extract only layer 61 weights."""
weights = {
"model.layers.60.self_attn.weight": mx.zeros((10, 10)),
"model.layers.61.enorm.weight": mx.ones((10,)),
"model.layers.61.hnorm.weight": mx.ones((10,)) * 2,
"model.layers.61.eh_proj.weight": mx.ones((10, 20)),
"model.layers.62.self_attn.weight": mx.zeros((10, 10)),
"model.embed_tokens.weight": mx.zeros((100, 10)),
}
mtp_weights = extract_mtp_weights(weights)
assert len(mtp_weights) == 3
assert "enorm.weight" in mtp_weights
assert "hnorm.weight" in mtp_weights
assert "eh_proj.weight" in mtp_weights
# Check values are preserved
assert mx.allclose(mtp_weights["enorm.weight"], mx.ones((10,)))
assert mx.allclose(mtp_weights["hnorm.weight"], mx.ones((10,)) * 2)
def test_returns_empty_dict_when_no_layer_61(self) -> None:
"""Should return empty dict when layer 61 doesn't exist."""
weights = {
"model.layers.0.self_attn.weight": mx.zeros((10, 10)),
"model.layers.60.self_attn.weight": mx.zeros((10, 10)),
}
mtp_weights = extract_mtp_weights(weights)
assert len(mtp_weights) == 0
def test_handles_nested_layer_61_weights(self) -> None:
"""Should handle nested weight paths like self_attn.q_proj.weight."""
weights = {
f"model.layers.{MTP_LAYER_INDEX}.self_attn.q_a_proj.weight": mx.zeros(
(10, 10)
),
f"model.layers.{MTP_LAYER_INDEX}.mlp.gate_proj.weight": mx.zeros((20, 10)),
}
mtp_weights = extract_mtp_weights(weights)
assert "self_attn.q_a_proj.weight" in mtp_weights
assert "mlp.gate_proj.weight" in mtp_weights
class TestMTPTransformerBlock:
"""Tests for MTPTransformerBlock."""
@pytest.fixture
def config(self) -> MockModelArgs:
return MockModelArgs(
hidden_size=64, intermediate_size=128, num_attention_heads=2
)
def test_forward_shape(self, config: MockModelArgs) -> None:
"""Forward pass should preserve input shape."""
# Skip if deepseek_v3 imports fail (CI without mlx_lm)
pytest.importorskip("mlx_lm.models.deepseek_v3")
block = MTPTransformerBlock(config) # type: ignore[arg-type]
x = mx.random.normal((1, 5, config.hidden_size))
output = block(x)
assert output.shape == x.shape
def test_forward_with_mask(self, config: MockModelArgs) -> None:
"""Forward pass should work with attention mask."""
pytest.importorskip("mlx_lm.models.deepseek_v3")
block = MTPTransformerBlock(config) # type: ignore[arg-type]
x = mx.random.normal((1, 5, config.hidden_size))
# Create causal mask
mask = mx.triu(mx.full((5, 5), float("-inf")), k=1)
output = block(x, mask=mask)
assert output.shape == x.shape
class TestMTPModule:
"""Tests for MTPModule."""
@pytest.fixture
def config(self) -> MockModelArgs:
return MockModelArgs(
hidden_size=64,
intermediate_size=128,
num_attention_heads=2,
vocab_size=100,
)
@pytest.fixture
def shared_components(
self, config: MockModelArgs
) -> tuple[nn.Embedding, nn.Linear, nn.RMSNorm]:
embedding = nn.Embedding(config.vocab_size, config.hidden_size)
lm_head = nn.Linear(config.hidden_size, config.vocab_size, bias=False)
output_norm = nn.RMSNorm(config.hidden_size, eps=config.rms_norm_eps)
return embedding, lm_head, output_norm
def test_initialization(
self,
config: MockModelArgs,
shared_components: tuple[nn.Embedding, nn.Linear, nn.RMSNorm],
) -> None:
"""MTPModule should initialize with correct components."""
pytest.importorskip("mlx_lm.models.deepseek_v3")
embedding, lm_head, output_norm = shared_components
mtp = MTPModule(
config=config, # type: ignore[arg-type]
shared_embedding=embedding,
shared_lm_head=lm_head,
output_norm=output_norm,
)
assert mtp.hnorm is not None
assert mtp.enorm is not None
assert mtp.eh_proj is not None
assert mtp.transformer_block is not None
def test_forward_output_shapes(
self,
config: MockModelArgs,
shared_components: tuple[nn.Embedding, nn.Linear, nn.RMSNorm],
) -> None:
"""Forward pass should return correct output shapes."""
pytest.importorskip("mlx_lm.models.deepseek_v3")
embedding, lm_head, output_norm = shared_components
mtp = MTPModule(
config=config, # type: ignore[arg-type]
shared_embedding=embedding,
shared_lm_head=lm_head,
output_norm=output_norm,
)
batch_size = 2
seq_len = 1
hidden_state = mx.random.normal((batch_size, seq_len, config.hidden_size))
draft_token = mx.array([[5], [10]]) # [batch, seq_len]
logits, new_hidden = mtp(hidden_state, draft_token)
assert logits.shape == (batch_size, seq_len, config.vocab_size)
assert new_hidden.shape == (batch_size, seq_len, config.hidden_size)
def test_shares_embedding_and_lm_head(
self,
config: MockModelArgs,
shared_components: tuple[nn.Embedding, nn.Linear, nn.RMSNorm],
) -> None:
"""MTPModule should use shared embedding and lm_head."""
pytest.importorskip("mlx_lm.models.deepseek_v3")
embedding, lm_head, output_norm = shared_components
mtp = MTPModule(
config=config, # type: ignore[arg-type]
shared_embedding=embedding,
shared_lm_head=lm_head,
output_norm=output_norm,
)
# Verify they're the same objects
assert mtp._shared_embedding is embedding
assert mtp._shared_lm_head is lm_head
assert mtp._output_norm is output_norm
class TestLoadMTPWeights:
"""Tests for load_mtp_weights_into_module."""
@pytest.fixture
def config(self) -> MockModelArgs:
return MockModelArgs(
hidden_size=64,
intermediate_size=128,
num_attention_heads=2,
vocab_size=100,
)
def test_loads_norm_weights(self, config: MockModelArgs) -> None:
"""Should load enorm and hnorm weights."""
pytest.importorskip("mlx_lm.models.deepseek_v3")
embedding = nn.Embedding(config.vocab_size, config.hidden_size)
lm_head = nn.Linear(config.hidden_size, config.vocab_size, bias=False)
output_norm = nn.RMSNorm(config.hidden_size, eps=config.rms_norm_eps)
mtp = MTPModule(
config=config, # type: ignore[arg-type]
shared_embedding=embedding,
shared_lm_head=lm_head,
output_norm=output_norm,
)
# Create test weights
test_enorm = mx.ones((config.hidden_size,)) * 3.0
test_hnorm = mx.ones((config.hidden_size,)) * 5.0
mtp_weights = {
"enorm.weight": test_enorm,
"hnorm.weight": test_hnorm,
}
load_mtp_weights_into_module(mtp, mtp_weights)
assert mx.allclose(mtp.enorm.weight, test_enorm)
assert mx.allclose(mtp.hnorm.weight, test_hnorm)
class TestSanitizePatch:
"""Tests for the sanitize patching logic."""
def test_patch_preserves_layer_61(self) -> None:
"""Patching sanitize should preserve layer 61 weights."""
from exo.worker.engines.mlx.utils_mlx import (
_patch_deepseek_sanitize_for_mtp,
_restore_deepseek_sanitize,
)
deepseek_v3 = pytest.importorskip("mlx_lm.models.deepseek_v3")
model_cls = deepseek_v3.Model
# Get original sanitize behavior
original_sanitize = model_cls.sanitize
try:
# Apply patch
_patch_deepseek_sanitize_for_mtp()
# Note: we can't easily test the full sanitize without a real model
# This test verifies the patch is applied
assert model_cls.sanitize is not original_sanitize
finally:
_restore_deepseek_sanitize()
# Verify restore worked
assert model_cls.sanitize is original_sanitize
def test_restore_sanitize(self) -> None:
"""Restoring sanitize should return to original behavior."""
from exo.worker.engines.mlx.utils_mlx import (
_patch_deepseek_sanitize_for_mtp,
_restore_deepseek_sanitize,
)
deepseek_v3 = pytest.importorskip("mlx_lm.models.deepseek_v3")
model_cls = deepseek_v3.Model
original_sanitize = model_cls.sanitize
_patch_deepseek_sanitize_for_mtp()
assert model_cls.sanitize is not original_sanitize
_restore_deepseek_sanitize()
assert model_cls.sanitize is original_sanitize
def test_double_patch_is_safe(self) -> None:
"""Calling patch twice should be safe (idempotent)."""
from exo.worker.engines.mlx.utils_mlx import (
_patch_deepseek_sanitize_for_mtp,
_restore_deepseek_sanitize,
)
deepseek_v3 = pytest.importorskip("mlx_lm.models.deepseek_v3")
model_cls = deepseek_v3.Model
original_sanitize = model_cls.sanitize
try:
_patch_deepseek_sanitize_for_mtp()
patched_sanitize = model_cls.sanitize
# Patch again - should be no-op
_patch_deepseek_sanitize_for_mtp()
assert model_cls.sanitize is patched_sanitize
finally:
_restore_deepseek_sanitize()
assert model_cls.sanitize is original_sanitize
class TestModelIdDetection:
"""Tests for DeepSeek V3 model ID detection."""
def test_detects_deepseek_v3(self) -> None:
"""Should detect DeepSeek V3 model IDs."""
from exo.worker.engines.mlx.utils_mlx import _might_be_deepseek_v3
assert _might_be_deepseek_v3("deepseek-ai/DeepSeek-V3")
assert _might_be_deepseek_v3("deepseek-ai/deepseek-v3-base")
assert _might_be_deepseek_v3("mlx-community/DeepSeek-V3-4bit")
def test_detects_deepseek_r1(self) -> None:
"""Should detect DeepSeek R1 model IDs (also uses MTP)."""
from exo.worker.engines.mlx.utils_mlx import _might_be_deepseek_v3
assert _might_be_deepseek_v3("deepseek-ai/DeepSeek-R1")
assert _might_be_deepseek_v3("mlx-community/DeepSeek-R1-4bit")
def test_rejects_non_deepseek(self) -> None:
"""Should reject non-DeepSeek model IDs."""
from exo.worker.engines.mlx.utils_mlx import _might_be_deepseek_v3
assert not _might_be_deepseek_v3("meta-llama/Llama-3-70B")
assert not _might_be_deepseek_v3("mistralai/Mixtral-8x7B")
assert not _might_be_deepseek_v3("deepseek-ai/DeepSeek-V2") # V2, not V3
def test_case_insensitive(self) -> None:
"""Detection should be case insensitive."""
from exo.worker.engines.mlx.utils_mlx import _might_be_deepseek_v3
assert _might_be_deepseek_v3("DEEPSEEK-AI/DEEPSEEK-V3")
assert _might_be_deepseek_v3("DeepSeek-AI/deepseek-v3")
class TestFlattenParams:
"""Tests for parameter flattening utility."""
def test_flattens_nested_dict(self) -> None:
"""Should flatten nested parameter dict."""
from exo.worker.engines.mlx.utils_mlx import _flatten_params
params = {
"model": {
"layers": {
"0": {
"weight": mx.zeros((10,)),
}
},
"embed": mx.ones((5,)),
}
}
flat = _flatten_params(params)
assert "model.layers.0.weight" in flat
assert "model.embed" in flat
assert mx.allclose(flat["model.layers.0.weight"], mx.zeros((10,)))
assert mx.allclose(flat["model.embed"], mx.ones((5,)))
def test_handles_flat_dict(self) -> None:
"""Should handle already-flat dict."""
from exo.worker.engines.mlx.utils_mlx import _flatten_params
params = {
"weight": mx.zeros((10,)),
"bias": mx.ones((10,)),
}
flat = _flatten_params(params)
assert flat == params
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"""Unit tests for MTP speculative decoding."""
import mlx.core as mx
import mlx.nn as nn
import pytest
from exo.worker.engines.mlx.mtp.speculative_decode import (
ModelWithHiddenStates,
maybe_quantize_kv_cache,
)
class MockModel(nn.Module):
"""Mock model for testing speculative decoding."""
def __init__(self, hidden_size: int = 64, vocab_size: int = 100) -> None:
super().__init__()
self.hidden_size = hidden_size
self.vocab_size = vocab_size
# Create simple model components
self.model = MockInnerModel(hidden_size)
self.lm_head = nn.Linear(hidden_size, vocab_size, bias=False)
self._layers = [nn.Linear(hidden_size, hidden_size) for _ in range(3)]
def __call__(
self,
inputs: mx.array,
cache: list | None = None,
) -> mx.array:
hidden = self.model(inputs, cache)
return self.lm_head(hidden)
@property
def layers(self) -> list[nn.Module]:
return self._layers
class MockInnerModel(nn.Module):
"""Mock inner model (like DeepseekV3Model)."""
def __init__(self, hidden_size: int) -> None:
super().__init__()
self.embed_tokens = nn.Embedding(100, hidden_size)
self.norm = nn.RMSNorm(hidden_size)
def __call__(
self,
inputs: mx.array,
cache: list | None = None,
) -> mx.array:
# Simple embedding + norm
embedded = self.embed_tokens(inputs)
return self.norm(embedded)
class TestModelWithHiddenStates:
"""Tests for ModelWithHiddenStates wrapper."""
@pytest.fixture
def mock_model(self) -> MockModel:
return MockModel(hidden_size=64, vocab_size=100)
def test_forward_returns_logits(self, mock_model: MockModel) -> None:
"""Standard forward should return logits."""
wrapped = ModelWithHiddenStates(mock_model)
inputs = mx.array([[1, 2, 3]])
logits = wrapped.forward(inputs)
assert logits.shape == (1, 3, mock_model.vocab_size)
def test_forward_with_hidden_returns_tuple(self, mock_model: MockModel) -> None:
"""Forward with hidden should return (logits, hidden)."""
wrapped = ModelWithHiddenStates(mock_model)
inputs = mx.array([[1, 2, 3]])
logits, hidden = wrapped.forward_with_hidden(inputs)
assert logits.shape == (1, 3, mock_model.vocab_size)
assert hidden.shape == (1, 3, mock_model.hidden_size)
def test_layers_property(self, mock_model: MockModel) -> None:
"""Should expose layers property from base model."""
wrapped = ModelWithHiddenStates(mock_model)
assert wrapped.layers == mock_model.layers
assert len(wrapped.layers) == 3
class TestMaybeQuantizeKVCache:
"""Tests for KV cache quantization."""
def test_no_quantization_when_bits_none(self) -> None:
"""Should not quantize when kv_bits is None."""
cache = [MockCache(offset=100)]
maybe_quantize_kv_cache(
cache,
quantized_kv_start=50,
kv_group_size=64,
kv_bits=None,
)
# Cache should be unchanged
assert not hasattr(cache[0], "quantized")
def test_respects_quantized_kv_start(self) -> None:
"""Should only quantize caches past the start threshold."""
cache_below = MockCache(offset=30)
cache_above = MockCache(offset=100)
caches = [cache_below, cache_above]
maybe_quantize_kv_cache(
caches,
quantized_kv_start=50,
kv_group_size=64,
kv_bits=4,
)
# Only cache_above should be quantized
assert not getattr(cache_below, "was_quantized", False)
assert getattr(caches[1], "was_quantized", False)
class MockCache:
"""Mock KV cache for testing."""
def __init__(self, offset: int = 0) -> None:
self.offset = offset
self.was_quantized = False
def to_quantized(self, group_size: int, bits: int) -> "MockCache":
quantized = MockCache(self.offset)
quantized.was_quantized = True
return quantized
class TestSpeculativeDecodingLogic:
"""Tests for the core speculative decoding logic."""
def test_draft_acceptance_identical_tokens(self) -> None:
"""When draft matches verification, both should be accepted."""
# This tests the logic, not the full generator
draft_token = 42
verify_token = 42
accepted = draft_token == verify_token
assert accepted
def test_draft_rejection_different_tokens(self) -> None:
"""When draft differs from verification, draft should be rejected."""
draft_token = 42
verify_token = 99
accepted = draft_token == verify_token
assert not accepted
class TestMTPGenerationResponse:
"""Tests for MTPGenerationResponse dataclass."""
def test_response_creation(self) -> None:
"""Should create response with all fields."""
from exo.worker.engines.mlx.mtp.speculative_decode import MTPGenerationResponse
response = MTPGenerationResponse(
text="Hello",
token=42,
logprobs=mx.array([0.1, 0.2]),
from_draft=True,
prompt_tokens=10,
prompt_tps=100.0,
generation_tokens=5,
generation_tps=50.0,
peak_memory=1.5,
finish_reason=None,
)
assert response.text == "Hello"
assert response.token == 42
assert response.from_draft is True
assert response.finish_reason is None
def test_response_with_finish_reason(self) -> None:
"""Should handle finish_reason."""
from exo.worker.engines.mlx.mtp.speculative_decode import MTPGenerationResponse
response = MTPGenerationResponse(
text="",
token=0,
logprobs=mx.array([0.0]),
from_draft=False,
prompt_tokens=10,
prompt_tps=100.0,
generation_tokens=100,
generation_tps=50.0,
peak_memory=1.5,
finish_reason="length",
)
assert response.finish_reason == "length"
class TestIntegration:
"""Integration tests for the full MTP pipeline."""
def test_mtp_module_with_mock_model(self) -> None:
"""Test MTP module can be created and run with mock components."""
pytest.importorskip("mlx_lm.models.deepseek_v3")
from exo.worker.engines.mlx.mtp.module import MTPModule
# Create mock config
class MockConfig:
hidden_size = 64
intermediate_size = 128
num_attention_heads = 2
num_key_value_heads = 2
rms_norm_eps = 1e-6
q_lora_rank = None
kv_lora_rank = 32
qk_rope_head_dim = 8
v_head_dim = 16
qk_nope_head_dim = 16
rope_theta = 10000.0
rope_scaling = None
attention_bias = False
max_position_embeddings = 2048
config = MockConfig()
embedding = nn.Embedding(100, config.hidden_size)
lm_head = nn.Linear(config.hidden_size, 100, bias=False)
output_norm = nn.RMSNorm(config.hidden_size)
mtp = MTPModule(
config=config, # type: ignore[arg-type]
shared_embedding=embedding,
shared_lm_head=lm_head,
output_norm=output_norm,
)
# Run forward pass
hidden = mx.random.normal((1, 1, config.hidden_size))
token = mx.array([[5]])
logits, new_hidden = mtp(hidden, token)
assert logits.shape == (1, 1, 100)
assert new_hidden.shape == (1, 1, config.hidden_size)
# Verify outputs are valid (not NaN)
assert not mx.any(mx.isnan(logits))
assert not mx.any(mx.isnan(new_hidden))
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@@ -3,6 +3,7 @@ import os
import resource
import sys
import time
from collections.abc import Callable
from pathlib import Path
from typing import Any, cast