Snapshot Testing

Purpose

Provide snapshot testing capabilities for vibe_piper data structures.

When To Use

• User wants to test that pipeline outputs, transformations, or data processing results remain consistent across code changes.
• Use snapshot testing to catch regressions in data processing logic.

API

from tests.helpers.snapshots import assert_match_snapshot, assert_json_snapshot, assert_snapshot_matches_data


# Create snapshot (auto-created on first run)
assert_match_snapshot(data, "my_pipeline_output")

# Compare against expected (shows diff if mismatch)
assert_match_snapshot(actual_data, "expected_snapshot")

Features

• JSON-based snapshot storage in tests/snapshots/
• Automatic snapshot creation on first run
• Diff visualization with unified diff on mismatches
• Max depth protection for nested structures
• Sorted keys for reproducibility
• Support for --update-snapshots flag to update existing snapshots

Data Types Supported

• Primitive types (str, int, float, bool, None)
• Collections (list, dict, tuple, set)
• Dataclasses with dict
• Nested structures up to max_depth (default 10)

Configuration

• update: If True, update the snapshot with new value
• test_file_path: Override auto-detection of test file path
• max_depth: Maximum nesting depth for serialization

Test Fixtures

• snapshot_tmp: Temporary directory for test snapshot files

Error Handling

• Clear diff output showing expected vs actual
• Line-by-line comparison using unified diff
• Helpful error messages with snapshot name

Usage Examples

# Test pipeline output against snapshot
def test_pipeline_output():
    result = pipeline.execute(data)
    assert_match_snapshot(result, "pipeline_output_snapshot")

# Test API response matches expected format
def test_api_response():
    response = api_client.get_users()
    assert_json_snapshot(response, "api_users_snapshot")

Dependencies

• Built-in: json, difflib, pathlib
• Test framework: pytest (via conftest and test imports)
• Vibe Piper types: Schema, DataRecord, etc.

Files

• tests/helpers/snapshots.py - Core implementation
• tests/helpers/test_snapshots.py - Test suite
• tests/snapshots/ - Snapshot storage directory

Manual notes

This section is preserved when the skill is updated. Put human notes, caveats, and exceptions here.