Fix flaky test_unique_id by making ID counter thread-local - #4
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`test_unique_id` reset the global ID counter and asserted exact values
(_1, _2, foo3), but the counter was a process-global AtomicUsize. Rust
runs tests in parallel within a binary, so other tests calling unique_id
(via layout -> acyclic's unique_id("rev")) concurrently bumped the
counter between assertions, intermittently producing "_3" instead of
"_2".
Generated IDs only need to be unique within a single graph, and a layout
runs entirely on one thread, so a thread-local counter is correct and
removes the cross-test interference. dagre layout has no internal
parallelism, and nothing relies on the counter being shared across
threads.
Verified deterministic over 150 consecutive runs of the dagre test
binary; full workspace suite green.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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cmwright
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Jun 9, 2026
Bump workspace crates to 0.1.2 and publish the fixes landed since 0.1.1: - Fix overlapping parallel edges between same node pair (#3) - Fix flaky test_unique_id: make ID counter thread-local (#4) Update inter-crate dependency pins (mermaid-core -> mermaid-dagre, mermaid-rs-cli -> mermaid-core) to 0.1.2. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Problem
util::tests::test_unique_idwas flaky, intermittently failing with:Reproduced reliably (~1 in 18 runs of the dagre test binary).
Root cause
The test resets the global ID counter and asserts exact values (
_1,_2,foo3). ButID_COUNTERwas a process-globalAtomicUsize, and Rust runs tests in parallel within a test binary. Other tests that callunique_idconcurrently — chiefly vialayout()→acyclic'sunique_id("rev")— bumped the counter between this test's assertions, so the second call returned_3instead of_2.Fix
Make the counter
thread_local!. Generated IDs only need to be unique within a single graph, and a dagre layout runs entirely on one thread (no rayon / thread spawning in the layout path), so a per-thread counter is correct. Each test thread now gets its own counter, eliminating cross-test interference while preserving the exact-value assertions.Nothing relies on the counter being shared across threads, and
add_dummy_nodeonly consultsunique_idon a name collision, so normal layout output (bare_d/_ep/_rootprefixes) is unchanged.Testing
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