Layout and the test you can afford

Open this once, after ls /testbed tells you which tree you are in. Then stop reading it.

astroid

Package root astroid/. Inference of builtins and third-party modules lives in astroid/brain/. Turning live objects into nodes is astroid/raw_building.py (attach_dummy_node, build_dummy). The bootstrapped builtin module is built from astroid/interpreter/objectmodel.py and the brain for builtins. Class bases, metaclasses, and six.with_metaclass are inferred in astroid/brain/brain_six.py and the class node in astroid/nodes/scoped_nodes. Tests sit in tests/, with tests/brain/ for the brains.

Run, from /testbed, the smallest file that names the symbol:

python -m pytest tests/brain/test_brain.py tests/brain/test_six.py -q --tb=line

Widen only if that file is not the one your symbol lives in. Use tests/test_builder.py, tests/test_inference.py, tests/test_nodes.py, tests/test_scoped_nodes.py, or tests/test_object_model.py the same way, one file at a time.

sqlglot

Package root sqlglot/. Parsing is sqlglot/parser.py. Dialects override tokens and generators under sqlglot/dialects/. Expressions are sqlglot/expressions.py. sqlglot.transpile is parse then generate. ALTER TABLE lives in the parser's alter rules and the expression for Alter / AlterColumn.

Run:

python -m pytest tests/test_transpile.py -q --tb=line -k alter

If the issue is identity of generated SQL rather than one statement, drop the -k and accept a longer run only after the first edit.

python-docx

Package root docx/. Section page setup is docx/section.py, backed by docx/oxml/section.py (CT_SectPr, CT_PageMar). Lengths are EMU in the public property and twips in w:pgMar attributes (w:top, w:bottom, w:left, w:right, w:header, w:footer, w:gutter). Shared length helpers are docx/shared.py.

Run:

python -m pytest tests/test_section.py -q --tb=line

python-pptx

Package root pptx/. Paragraph spacing is pptx/text/text.py (Paragraph, space_before, space_after, line_spacing) writing a:spcBef / a:spcAft / a:lnSpc through pptx/oxml/text.py. A setter must update the child it owns and leave sibling spacing elements in place.

Run:

python -m pytest tests/text/test_text.py -q --tb=line

Shared

PYTHONPATH=/testbed if the package is not installed. Add --tb=line -q always. Do not pass --snapshot-update or any flag that rewrites fixtures.