litert-model-equivalence-test

Testing & Quality

Validates equivalence between LiteRT models (litert_lm) and PyTorch models (transformers). Use when you need to verify that an exported LiteRT model produces the same outputs as the original Hugging Face model. Supports multi-turn conversations and custom prompts.

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LiteRT Model Equivalence Test

This skill provides instructions for running equivalence tests between LiteRT models and their PyTorch source models.

Usage

Use the equivalence_test script to compare the outputs of a Hugging Face model and its exported LiteRT version.

Running the Test

Run the test using bazel run from your workspace:

bazel run \
  //third_party/py/litert_torch/generative/export_hf/experimental/validation:equivalence_test \
  -- \
  --model_id={model_id} \
  [--prompt={prompt}] \
  [--prompt_file={prompt_file}] \
  [--max_new_tokens={max_new_tokens}] \
  [--max_num_tokens={max_num_tokens}] \
  [--work_dir={work_dir}] \
  [--externalize_embedder] \
  [--single_token_embedder] \
  [--split_cache] \
  [--backend={backend}]

Flags

--model_id: The Hugging Face model ID to validate (e.g., google/gemma-3-270m-it).
--prompt: Prompt to test. Specify multiple times for multi-turn conversations.
--prompt_file: Path to a file containing one (complex) prompt. Overrides --prompt.
--max_new_tokens: Maximum new tokens to generate per turn (default: 20).
--max_num_tokens: KV cache length for the model (default: 2048).
--work_dir: Base directory for model export. If not specified, a temporary directory under HOME is used.
--externalize_embedder: Externalize the embedder during export (default: False).
--single_token_embedder: Use single token embedder during export (default: False).
--split_cache: Split KV cache during export (default: False).
--backend: Hardware backend to use for LiteRT LM (cpu | npu, default: cpu).

Examples

Single-turn test with custom prompt:

bazel run \
  //third_party/py/litert_torch/generative/export_hf/experimental/validation:equivalence_test \
  -- \
  --model_id=google/gemma-3-270m-it \
  --prompt="What is the capital of France?"

Multi-turn test:

bazel run \
  //third_party/py/litert_torch/generative/export_hf/experimental/validation:equivalence_test \
  -- \
  --model_id=google/gemma-3-270m-it \
  --prompt="What's the capital of France?" \
  --prompt="How about Germany?"

Testing with a prompt file:

bazel run \
  //third_party/py/litert_torch/generative/export_hf/experimental/validation:equivalence_test \
  -- \
  --model_id=google/gemma-3-270m-it \
  --prompt_file=/path/to/prompts.txt

Testing with externalized embedder:

bazel run \
  //third_party/py/litert_torch/generative/export_hf/experimental/validation:equivalence_test \
  -- \
  --model_id=google/gemma-3-270m-it \
  --externalize_embedder \
  --single_token_embedder

Testing NPU export variant:

bazel run \
  //third_party/py/litert_torch/generative/export_hf/experimental/validation:equivalence_test \
  -- \
  --model_id=google/gemma-3-270m-it \
  --externalize_embedder \
  --split_cache \
  --backend=npu