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 TrainingStep

Problem

When using a TrainingStep in a Pipeline where SourceCode.requirements is not set (defaults to None), calling pipeline.upsert() raises a TypeError: can only concatenate list (not 'NoneType') to list. This occurs during the code hash computation in get_code_hash() → get_training_code_hash().

Root Cause

The get_code_hash() function reads source_code.requirements which can be None and passes it directly to get_training_code_hash() as the dependencies parameter. While get_training_code_hash() already has if dependencies: guards to prevent concatenation with None, the get_code_hash() function did not normalize falsy values (like empty strings) before passing them through.

Fix

1. Defensive normalization in get_code_hash(): Changed requirements = source_code.requirements to requirements = source_code.requirements or None to handle both None and empty string edge cases.
2. Verified existing guards: The get_training_code_hash() function already correctly checks if dependencies: before attempting list concatenation, which handles the None case.

Tests Added

• test_get_training_code_hash_with_none_dependencies_source_dir - Verifies no TypeError when dependencies is None with source_dir
• test_get_training_code_hash_with_none_dependencies_entry_point_only - Verifies no TypeError when dependencies is None with entry_point only
• test_get_training_code_hash_with_default_dependencies - Verifies the default parameter value works correctly
• test_get_code_hash_training_step_with_no_requirements - End-to-end test with mock TrainingStep and None requirements
• test_get_code_hash_training_step_with_empty_string_requirements - End-to-end test with mock TrainingStep and empty string requirements

Related Issue

Fixes aws#5518

Changes Made

The bug occurs when SourceCode.requirements is not set (defaults to None) and a TrainingStep is used in a Pipeline. During pipeline.upsert() → definition() → get_code_hash(step), the code reads source_code.requirements (which is None) and passes it to get_training_code_hash() as the dependencies parameter. In the version the user is running (3.3.1), the function attempts [source_dir] + dependencies where dependencies is None, causing TypeError: can only concatenate list (not 'NoneType') to list. The current repo code already has if dependencies: guards in get_training_code_hash, but the fix needs to be verified as complete and properly tested. Additionally, the get_code_hash function in utilities.py should defensively handle None requirements before passing to get_training_code_hash to prevent this class of error.

AI-Generated PR

This PR was automatically generated by the PySDK Issue Agent.

• Confidence score: 88%
• 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)