fix(core/singletask): guard BASE_MODEL_URL assignment against None in…

[g-k-s-03]

Description

SingleTaskLearning._train() unconditionally assigns
os.environ["BASE_MODEL_URL"] = initial_model, where initial_model
is None when initial_model_url is absent from the algorithm YAML.
This raises TypeError: str expected, not NoneType immediately.

A secondary issue exists in multi-test-case benchmarks: when test
cases run sequentially in the same process via testcase.py, a stale
BASE_MODEL_URL set by a prior test case persists into subsequent
ones that omit initial_model_url, causing the wrong pretrained
checkpoint to be loaded silently.

Fix

Replaced the unconditional assignment with a guarded block:

if initial_model is not None:
    os.environ["BASE_MODEL_URL"] = initial_model
else:
    os.environ.pop("BASE_MODEL_URL", None)

The pop with a default value clears any stale entry from a prior
test case, preventing cross-test-case environment pollution.

Files Changed

• core/testcasecontroller/algorithm/paradigm/singletask_learning/singletask_learning.py

Fixes #574

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[gemini-code-assist]

Code Review

This pull request updates the _train method in singletask_learning.py to conditionally set or remove the BASE_MODEL_URL environment variable depending on whether initial_model is provided. The review feedback suggests a more robust check (if initial_model:) to handle both None and empty string values, preventing potential issues in downstream components that check for the presence of this environment variable.

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[gemini-code-assist]

In Algorithm, self.initial_model_url is initialized as an empty string ("") by default. If initial_model_url is omitted from the configuration, initial_model can be passed as "" rather than None.

Setting os.environ["BASE_MODEL_URL"] = "" can cause issues in downstream components or subprocesses that check for the presence of the environment variable (e.g., "BASE_MODEL_URL" in os.environ).

To make this guard more robust against both None and empty strings, consider checking if initial_model: instead of if initial_model is not None:.

Suggested change

	if initial_model is not None:
	os.environ["BASE_MODEL_URL"] = initial_model
	else:
	os.environ.pop("BASE_MODEL_URL", None)
	if initial_model:
	os.environ["BASE_MODEL_URL"] = initial_model
	else:
	os.environ.pop("BASE_MODEL_URL", None)

[g-k-s-03]

Valid point; updated to if initial_model: to handle both None and empty string cases, since self.initial_model_url defaults to "" in the base class