Testing

Unit suites

The interpreter has no test framework dependency — tests are @main-style objects with a hand-rolled PASS/FAIL runner. The same code runs on all three backends:

sbt 'interpJVM/Test/run'    # 653 interpreter tests
sbt 'interpJS/Test/run'
sbt 'interpNative/Test/run'

sbt 'wasiJVM/Test/run'      # 209 WASI tests on JVM/Native (193 on JS,
sbt 'wasiJS/Test/run'       #                   16 socket tests skipped)
sbt 'wasiNative/Test/run'

sbt 'cliJVM/Test/run'       # 19 CLI tests (JVM-only)

Total: 881 tests on JVM (653 interp + 209 wasi + 19 cli) — all three backends green for interp and wasi. Three of those are end-to-end integration tests against real rustc-built wasm32-wasip1 binaries.

Each Test/run target prints one OK <name> or FAIL <name> — <reason> line per assertion plus a final summary; the process exits non-zero if any assertion failed. Add new tests by appending test("name") { ... } calls inside the appropriate category file under interp/shared/src/test/scala/io/github/edadma/wasm/.

W3C testsuite

The official WebAssembly testsuite runs through an integrated runner — ~53,000 assertions across 142 manifests covering numerics, control flow, memory addressing, function pointers, the complete SIMD proposal, bulk memory + tables + element segments, EH and tail-call proposals, plus binary-format and UTF-8 edge cases.

./scripts/build-spec-tests.sh /path/to/wasm-testsuite     # one-time, regenerates JSON fixtures# one-time, regenerates JSON fixtures
sbt 'interpJVM/Test/runMain io.github.edadma.wasm.spec.SpecComplianceTests'

The runner consumes wast2json JSON command manifests + per-module .wasm binaries; it never parses .wast text. The script’s curated slice is the FILES=(...) array — append a manifest name and re-run to expand coverage.

See Reference → Spec compliance for current pass / fail / known-failure totals and the manifests pinned in KnownFailures.

Regenerating fixtures

The .wasm test fixtures are produced from hand-written .wat files with wat2wasm (from WABT). The committed .wasm binaries let anyone run the tests without WABT installed; Fixtures.scala is regenerated automatically on every sbt compile.

After editing any .wat:

cd interp/shared/src/test/resources/fixtures
for f in *.wat; do wat2wasm "$f" -o "${f%.wat}.wasm"; done

cd wasi/shared/src/test/resources/fixtures
for f in *.wat; do wat2wasm "$f" -o "${f%.wat}.wasm"; done

The three rustc-built fixtures are committed with their .rs source alongside as documentation; they’re rebuilt by hand when their semantics change (Cargo + the wasm32-wasip1 target).