[ci] move fanout_test_helpers to tests/

slime/rollout/_fanout_test_helpers.py → tests/fanout_test_helpers.py

@@ -1,11 +1,8 @@
-"""Test-internal compact-rollout helpers used by ``test_qwen2.5_0.5B_fanout_short.py``.
-
-The underscore prefix marks this as test infrastructure — it is not part
-of the user-facing slime API and is not re-exported anywhere. It lives
-in ``slime/`` only so the test can reference it by a dotted module path
-(``--custom-generate-function-path`` / ``--custom-reward-post-process-path``
-resolve a string via ``importlib.import_module``, which can't handle the
-dots in the e2e test's filename).
+"""Compact-rollout helpers for ``test_qwen2.5_0.5B_fanout_short.py``.
+
+These helpers are imported by module path from the Ray job started by the E2E
+test. They live on the test-only portion of ``PYTHONPATH`` because they are
+test fixtures, not part of slime's public or internal runtime API.
 
 Two helpers:
 

tests/test_qwen2.5_0.5B_fanout_short.py

@@ -20,10 +20,9 @@
        num_rollouts (not num_samples), keeping grad magnitude stable
        independent of fan-out
 
-The fan-out function itself lives in
-``slime/rollout/_fanout_test_helpers.py`` — it has to be at a dot-free
-module path so ``importlib.import_module`` can resolve the string
-``--custom-generate-function-path`` flag (this filename has dots).
+The fan-out functions live in ``tests/fanout_test_helpers.py``. The
+dedicated helper module gives ``importlib.import_module`` a valid module
+path even though this E2E test's filename itself contains dots.
 
 Test choices
 ------------
@@ -47,6 +46,7 @@
 MODEL_NAME = "Qwen2.5-0.5B-Instruct"
 MODEL_TYPE = "qwen2.5-0.5B"
 NUM_GPUS = 4
+TESTS_DIR = os.path.dirname(os.path.abspath(__file__))
 
 # Counter file used by the compact_generate helper. We pass its path
 # through to the Ray-submitted job via an env var so all worker
@@ -99,7 +99,7 @@ def execute():
         "--rollout-temperature 0.8 "
         "--global-batch-size 4 "
         "--balance-data "
-        "--custom-generate-function-path slime.rollout._fanout_test_helpers.compact_generate "
+        "--custom-generate-function-path fanout_test_helpers.compact_generate "
         # GRPO normalization needs per-prompt grouping. The default
         # ``_post_process_rewards`` (slime/ray/rollout.py:618) reshapes
         # by ``n_samples_per_prompt`` and falls back to "one big group"
@@ -109,7 +109,7 @@ def execute():
         # compact_generate preserves it across siblings) so each prompt's
         # siblings normalize against each other, matching the GRPO
         # semantics the default targets in the uniform case.
-        "--custom-reward-post-process-path slime.rollout._fanout_test_helpers.grpo_normalize_by_group_index "
+        "--custom-reward-post-process-path fanout_test_helpers.grpo_normalize_by_group_index "
     )
 
     perf_args = (
@@ -186,9 +186,13 @@ def execute():
         train_args=train_args,
         num_gpus_per_node=NUM_GPUS,
         megatron_model_type=MODEL_TYPE,
-        # Make the counter path visible inside the Ray-submitted job
-        # (helper picks it up via os.environ).
-        extra_env_vars={"SLIME_FANOUT_TEST_COUNTER_FILE": FANOUT_COUNTER_FILE},
+        extra_env_vars={
+            # Make the helper importable by both the Ray driver and workers
+            # without installing test modules as part of the slime package.
+            "PYTHONPATH": f"{TESTS_DIR}:{U.repo_base_dir}:/root/Megatron-LM/",
+            # The helper picks up the shared counter path via os.environ.
+            "SLIME_FANOUT_TEST_COUNTER_FILE": FANOUT_COUNTER_FILE,
+        },
     )
 
     # Post-train assertion: compact_generate must have been called exactly