Rendered from docs/verifications/0003-a-fixture-tree-of-three-list-anchors-proves-that-the-export-carries-list-members.md in the Headwater corpus. Every document on this half of the site is typed by the taxonomy the descriptor names: corpus.json.

A fixture tree of three list anchors proves that the export carries list members

Approach

The fixture tree at engine/crates/generate/fixtures/listanchor/ holds one decision, docs/decisions/0001-govern-two-lists.md, with the identifier DR-FIX-0001. engine/crates/generate/fixtures/listanchor.taxonomy.yml declares its kind and its relations.

The decision governs four entries, and each one is a case of HW-AC-0004:

  • src/c.rs is a single pattern, which carries no patterns field.
  • [src/a.rs, src/b.rs] is a list of two members.
  • [src/c.rs, "src/a, b.txt"] holds a member whose name holds ,. An emitter that split a joined display string on , reads three members there and fails.
  • [src/c.rs, src/b.rs, src/a.rs] holds three members out of order. An emitter that wrote members only for a list of exactly two drops it, and one that did not sort them writes the wrong order.

The four files under src/ hold no code. They exist because a code_path anchor binds only when its pattern matches at least one entry on the tree.

The test the_native_export_carries_the_members_of_a_list_anchor in engine/crates/generate/tests/fixtures.rs builds the corpus and emits the native JSON export with the default profile. It reads the export back, and it first checks that there are four anchor nodes and four anchor edges. It then compares the patterns field of each node and edge target with the expected members.

cargo test -p headwater-generate --test fixtures the_native_export_carries_the_members_of_a_list_anchor --manifest-path engine/Cargo.toml --locked

What this does not cover

The test reads the native JSON export only. It does not read any other emitter, and it does not read the text form of headwater explain.

This document governs the fixture tree and its taxonomy, and not the test file. engine/crates/generate/tests/fixtures.rs holds many other tests, and this document states the design of one of them. The doc comment of that test cites HW-VER-0003, and that comment binds the cited_in edge.