fix: Pipeline TypeError: can only concatenate list (not "NoneType") to list Using Sou (#5518)

[aviruthen]

Description

Fix TypeError when SourceCode.requirements is None in Pipeline

Fixes a TypeError that occurs when using SourceCode without setting requirements (which defaults to None) in a Pipeline context.

Problem

When SourceCode.requirements is None and a TrainingStep is compiled in a pipeline, the None value is passed as the dependencies parameter to get_training_code_hash(). While the function has if dependencies: guards in some branches, the get_processing_code_hash() function performs list concatenation ([source_dir] + dependencies) without checking if dependencies is None, which would cause a TypeError: can only concatenate list (not "NoneType") to list.

Fix

Added defensive dependencies = dependencies or [] at the start of both:

• get_processing_code_hash()
• get_training_code_hash()

This ensures dependencies is always a list, preventing TypeError from list concatenation with None and providing defense-in-depth even where existing if dependencies: guards exist.

Testing

Added test cases:

• test_get_training_code_hash_with_none_dependencies_source_dir — source_dir with dependencies=None
• test_get_training_code_hash_with_entry_point_only_and_none_dependencies — entry_point only with dependencies=None
• test_get_processing_code_hash_with_none_dependencies_source_dir — source_dir with dependencies=None
• test_get_processing_code_hash_with_none_dependencies_code_only — code only with dependencies=None

Related Issue

Fixes aws#5518

Changes Made

The bug occurs when SourceCode.requirements is not set (defaults to None), which gets passed as the dependencies parameter to get_training_code_hash() in sagemaker-core/src/sagemaker/core/workflow/utilities.py. The current code already has if dependencies: guards in get_training_code_hash, but the defensive fix of defaulting None to [] at the start of the function is more robust and prevents regressions. Additionally, get_processing_code_hash has the same latent bug where it performs [source_dir] + dependencies / [code] + dependencies without checking if dependencies is None. Both functions should default None dependencies to an empty list at the start of the function body.

AI-Generated PR

This PR was automatically generated by the PySDK Issue Agent.

• Confidence score: 92%
• Classification: bug
• SDK version target: V3

Merge Checklist

• Changes are backward compatible
• Commit message follows prefix: description format
• Unit tests added/updated
• Integration tests added (if applicable)
• Documentation updated (if applicable)

[aviruthen]

Can you add a comment over your source code changes explaining why you default to []?