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mlx-video/tests/test_wan_attention.py

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Python

"""Tests for Wan attention components and RoPE."""
import mlx.core as mx
import numpy as np
# ---------------------------------------------------------------------------
# RoPE Tests
# ---------------------------------------------------------------------------
class TestRoPE:
"""Tests for 3-way factorized RoPE."""
def test_rope_params_shape(self):
from mlx_video.models.wan2.rope import rope_params
freqs = rope_params(1024, 64)
mx.eval(freqs)
assert freqs.shape == (1024, 32, 2) # [max_seq_len, dim//2, 2]
def test_rope_params_different_dims(self):
from mlx_video.models.wan2.rope import rope_params
for dim in [32, 64, 128]:
freqs = rope_params(512, dim)
mx.eval(freqs)
assert freqs.shape == (512, dim // 2, 2)
def test_rope_params_cos_sin_range(self):
from mlx_video.models.wan2.rope import rope_params
freqs = rope_params(256, 64)
mx.eval(freqs)
cos_vals = np.array(freqs[:, :, 0])
sin_vals = np.array(freqs[:, :, 1])
assert np.all(cos_vals >= -1.0) and np.all(cos_vals <= 1.0)
assert np.all(sin_vals >= -1.0) and np.all(sin_vals <= 1.0)
def test_rope_params_position_zero(self):
"""At position 0, cos should be 1 and sin should be 0."""
from mlx_video.models.wan2.rope import rope_params
freqs = rope_params(10, 64)
mx.eval(freqs)
np.testing.assert_allclose(np.array(freqs[0, :, 0]), 1.0, atol=1e-6)
np.testing.assert_allclose(np.array(freqs[0, :, 1]), 0.0, atol=1e-6)
def test_rope_apply_output_shape(self):
from mlx_video.models.wan2.rope import rope_apply, rope_params
B, L, N, D = 1, 24, 4, 32 # batch, seq, heads, head_dim
x = mx.random.normal((B, L, N, D))
freqs = rope_params(1024, D)
grid_sizes = [(2, 3, 4)] # F*H*W = 24 = L
out = rope_apply(x, grid_sizes, freqs)
mx.eval(out)
assert out.shape == (B, L, N, D)
def test_rope_apply_preserves_norm(self):
"""RoPE rotation should preserve vector norms."""
from mlx_video.models.wan2.rope import rope_apply, rope_params
B, N, D = 1, 2, 16
F, H, W = 2, 3, 4
L = F * H * W
x = mx.random.normal((B, L, N, D))
freqs = rope_params(1024, D)
out = rope_apply(x, [(F, H, W)], freqs)
mx.eval(x, out)
x_np = np.array(x[0])
out_np = np.array(out[0])
for i in range(L):
for h in range(N):
norm_in = np.linalg.norm(x_np[i, h])
norm_out = np.linalg.norm(out_np[i, h])
np.testing.assert_allclose(norm_in, norm_out, rtol=1e-4)
def test_rope_apply_with_padding(self):
"""When seq_len < L, extra tokens should be preserved unchanged."""
from mlx_video.models.wan2.rope import rope_apply, rope_params
B, N, D = 1, 2, 16
F, H, W = 2, 2, 2
seq_len = F * H * W # 8
pad = 4
L = seq_len + pad
x = mx.random.normal((B, L, N, D))
freqs = rope_params(1024, D)
out = rope_apply(x, [(F, H, W)], freqs)
mx.eval(x, out)
# Padded tokens should be unchanged
np.testing.assert_allclose(
np.array(out[0, seq_len:]),
np.array(x[0, seq_len:]),
atol=1e-6,
)
def test_rope_apply_batch(self):
"""Test with batch_size > 1 and different grid sizes."""
from mlx_video.models.wan2.rope import rope_apply, rope_params
B, N, D = 2, 2, 16
grids = [(2, 3, 4), (2, 3, 4)]
L = 2 * 3 * 4
x = mx.random.normal((B, L, N, D))
freqs = rope_params(1024, D)
out = rope_apply(x, grids, freqs)
mx.eval(out)
assert out.shape == (B, L, N, D)
def test_rope_frequency_split(self):
"""Verify the 3-way frequency dimension split matches Wan2.2 convention."""
D = 128 # head_dim for 14B model
half_d = D // 2
d_t = half_d - 2 * (half_d // 3)
d_h = half_d // 3
d_w = half_d // 3
assert d_t + d_h + d_w == half_d
# Temporal gets more capacity
assert d_t >= d_h
assert d_t >= d_w
# ---------------------------------------------------------------------------
# Attention Tests
# ---------------------------------------------------------------------------
class TestWanRMSNorm:
def test_output_shape(self):
from mlx_video.models.wan2.attention import WanRMSNorm
norm = WanRMSNorm(64)
x = mx.random.normal((2, 10, 64))
out = norm(x)
mx.eval(out)
assert out.shape == (2, 10, 64)
def test_zero_mean_variance(self):
"""RMS norm should make RMS ≈ 1 before scaling."""
from mlx_video.models.wan2.attention import WanRMSNorm
norm = WanRMSNorm(64)
x = mx.random.normal((1, 5, 64)) * 10.0
out = norm(x)
mx.eval(out)
out_np = np.array(out[0])
for i in range(5):
rms = np.sqrt(np.mean(out_np[i] ** 2))
# After RMS norm with weight=1, RMS should be ~1
np.testing.assert_allclose(rms, 1.0, rtol=0.1)
def test_dtype_preservation(self):
"""RMSNorm weight is float32, so output is promoted to float32."""
from mlx_video.models.wan2.attention import WanRMSNorm
norm = WanRMSNorm(32)
x = mx.random.normal((1, 4, 32)).astype(mx.bfloat16)
out = norm(x)
mx.eval(out)
# Weight is float32, so multiplication promotes result to float32
assert out.dtype == mx.float32
class TestWanLayerNorm:
def test_output_shape(self):
from mlx_video.models.wan2.attention import WanLayerNorm
norm = WanLayerNorm(64)
x = mx.random.normal((2, 10, 64))
out = norm(x)
mx.eval(out)
assert out.shape == (2, 10, 64)
def test_without_affine(self):
from mlx_video.models.wan2.attention import WanLayerNorm
norm = WanLayerNorm(64, elementwise_affine=False)
x = mx.random.normal((1, 4, 64))
out = norm(x)
mx.eval(out)
# Mean should be ~0, variance should be ~1
out_np = np.array(out[0])
for i in range(4):
np.testing.assert_allclose(np.mean(out_np[i]), 0.0, atol=0.05)
np.testing.assert_allclose(np.std(out_np[i]), 1.0, rtol=0.1)
def test_with_affine(self):
from mlx_video.models.wan2.attention import WanLayerNorm
norm = WanLayerNorm(32, elementwise_affine=True)
assert hasattr(norm, "weight")
assert hasattr(norm, "bias")
x = mx.random.normal((1, 4, 32))
out = norm(x)
mx.eval(out)
assert out.shape == (1, 4, 32)
class TestWanSelfAttention:
def setup_method(self):
mx.random.seed(42)
self.dim = 64
self.num_heads = 4
def test_output_shape(self):
from mlx_video.models.wan2.attention import WanSelfAttention
from mlx_video.models.wan2.rope import rope_params
attn = WanSelfAttention(self.dim, self.num_heads)
B, L = 1, 24
F, H, W = 2, 3, 4
x = mx.random.normal((B, L, self.dim))
freqs = rope_params(1024, self.dim // self.num_heads)
out = attn(x, seq_lens=[L], grid_sizes=[(F, H, W)], freqs=freqs)
mx.eval(out)
assert out.shape == (B, L, self.dim)
def test_with_qk_norm(self):
from mlx_video.models.wan2.attention import WanSelfAttention
attn = WanSelfAttention(self.dim, self.num_heads, qk_norm=True)
assert attn.norm_q is not None
assert attn.norm_k is not None
def test_without_qk_norm(self):
from mlx_video.models.wan2.attention import WanSelfAttention
attn = WanSelfAttention(self.dim, self.num_heads, qk_norm=False)
assert attn.norm_q is None
assert attn.norm_k is None
def test_masking(self):
"""Test that masking works: shorter seq_lens should mask later tokens."""
from mlx_video.models.wan2.attention import WanSelfAttention
from mlx_video.models.wan2.rope import rope_params
attn = WanSelfAttention(self.dim, self.num_heads, qk_norm=False)
B, L = 1, 24
F, H, W = 2, 3, 4
x = mx.random.normal((B, L, self.dim))
freqs = rope_params(1024, self.dim // self.num_heads)
# Full sequence
out_full = attn(x, seq_lens=[L], grid_sizes=[(F, H, W)], freqs=freqs)
# Shorter sequence (mask last 4 tokens)
out_masked = attn(x, seq_lens=[L - 4], grid_sizes=[(F, H, W)], freqs=freqs)
mx.eval(out_full, out_masked)
# Outputs should differ when masking is applied
assert not np.allclose(np.array(out_full), np.array(out_masked), atol=1e-5)
class TestWanCrossAttention:
def setup_method(self):
mx.random.seed(42)
self.dim = 64
self.num_heads = 4
def test_output_shape(self):
from mlx_video.models.wan2.attention import WanCrossAttention
attn = WanCrossAttention(self.dim, self.num_heads)
B, L_q, L_kv = 1, 24, 16
x = mx.random.normal((B, L_q, self.dim))
context = mx.random.normal((B, L_kv, self.dim))
out = attn(x, context)
mx.eval(out)
assert out.shape == (B, L_q, self.dim)
def test_with_context_mask(self):
from mlx_video.models.wan2.attention import WanCrossAttention
attn = WanCrossAttention(self.dim, self.num_heads)
B, L_q, L_kv = 1, 12, 16
x = mx.random.normal((B, L_q, self.dim))
context = mx.random.normal((B, L_kv, self.dim))
out = attn(x, context, context_lens=[10])
mx.eval(out)
assert out.shape == (B, L_q, self.dim)
# ---------------------------------------------------------------------------
# bfloat16 Autocast Tests
# ---------------------------------------------------------------------------
class TestBFloat16Autocast:
"""Tests that attention and FFN cast inputs to weight dtype (bfloat16)
for efficient matmul, matching official PyTorch autocast behavior."""
def setup_method(self):
mx.random.seed(42)
self.dim = 64
self.num_heads = 4
@staticmethod
def _to_bf16(params):
"""Recursively cast all arrays in params to bfloat16."""
if isinstance(params, dict):
return {k: TestBFloat16Autocast._to_bf16(v) for k, v in params.items()}
elif isinstance(params, list):
return [TestBFloat16Autocast._to_bf16(v) for v in params]
elif isinstance(params, mx.array):
return params.astype(mx.bfloat16)
return params
def test_self_attn_casts_to_weight_dtype(self):
"""Self-attention should cast input to weight dtype for QKV projections."""
from mlx_video.models.wan2.attention import WanSelfAttention
from mlx_video.models.wan2.rope import rope_params
attn = WanSelfAttention(self.dim, self.num_heads)
attn.update(self._to_bf16(attn.parameters()))
x = mx.random.normal((1, 8, self.dim))
freqs = rope_params(1024, self.dim // self.num_heads)
out = attn(x, seq_lens=[8], grid_sizes=[(2, 2, 2)], freqs=freqs)
mx.eval(out)
assert out.shape == (1, 8, self.dim)
assert np.isfinite(np.array(out.astype(mx.float32))).all()
def test_cross_attn_casts_to_weight_dtype(self):
"""Cross-attention should cast input to weight dtype."""
from mlx_video.models.wan2.attention import WanCrossAttention
attn = WanCrossAttention(self.dim, self.num_heads)
attn.update(self._to_bf16(attn.parameters()))
x = mx.random.normal((1, 8, self.dim))
ctx = mx.random.normal((1, 4, self.dim))
out = attn(x, ctx)
mx.eval(out)
assert out.shape == (1, 8, self.dim)
assert np.isfinite(np.array(out.astype(mx.float32))).all()
def test_cross_attn_kv_cache_uses_weight_dtype(self):
"""prepare_kv should cast context to weight dtype."""
from mlx_video.models.wan2.attention import WanCrossAttention
attn = WanCrossAttention(self.dim, self.num_heads)
attn.update(self._to_bf16(attn.parameters()))
ctx = mx.random.normal((1, 4, self.dim))
k, v = attn.prepare_kv(ctx)
mx.eval(k, v)
assert k.dtype == mx.bfloat16
assert v.dtype == mx.bfloat16
def test_ffn_casts_to_weight_dtype(self):
"""FFN should cast input to weight dtype for linear layers."""
from mlx_video.models.wan2.transformer import WanFFN
ffn = WanFFN(self.dim, 128)
ffn.update(self._to_bf16(ffn.parameters()))
x = mx.random.normal((1, 8, self.dim))
out = ffn(x)
mx.eval(out)
assert out.shape == (1, 8, self.dim)
assert np.isfinite(np.array(out.astype(mx.float32))).all()
def test_self_attn_rope_in_float32(self):
"""RoPE should be applied in float32 for precision, even with bf16 weights."""
from mlx_video.models.wan2.attention import WanSelfAttention
from mlx_video.models.wan2.rope import rope_params
attn = WanSelfAttention(self.dim, self.num_heads)
attn.update(self._to_bf16(attn.parameters()))
x = mx.random.normal((1, 8, self.dim))
freqs = rope_params(1024, self.dim // self.num_heads)
assert freqs.dtype == mx.float32
out = attn(x, seq_lens=[8], grid_sizes=[(2, 2, 2)], freqs=freqs)
mx.eval(out)
assert np.isfinite(np.array(out.astype(mx.float32))).all()
def test_block_float32_residual_with_bf16_weights(self):
"""Full block: residual stream stays float32, matmuls use bf16 weights."""
from mlx_video.models.wan2.rope import rope_params
from mlx_video.models.wan2.transformer import WanAttentionBlock
block = WanAttentionBlock(self.dim, 128, self.num_heads, cross_attn_norm=True)
block.update(self._to_bf16(block.parameters()))
B, L = 1, 8
x = mx.random.normal((B, L, self.dim))
e = mx.random.normal((B, L, 6, self.dim))
ctx = mx.random.normal((B, 4, self.dim))
freqs = rope_params(1024, self.dim // self.num_heads)
out = block(x, e, [L], [(2, 2, 2)], freqs, ctx)
mx.eval(out)
assert out.dtype == mx.float32
assert np.isfinite(np.array(out)).all()