Verify the round trip

A verification is a typed claim about a lens property. Here we test whether put(get(source)) returns source for three records: ordinary text, an empty string, and Unicode text.

Run the verifier

From the repository root:

cargo run --quiet \
  --manifest-path scripts/publish-tutorial-lens/Cargo.toml \
  --bin verify-tutorial-lens

result = Holds
kind   = RoundtripTest
tool   = idiolect-verify/roundtrip-test 0.12.1

The executable gives the corpus to RoundtripTestRunner and runs it against the published lens:

let runner = RoundtripTestRunner::new(
    resolver,
    loader,
    Protocol::default(),
    corpus,
);
let verification = runner.run(&target).await?;

For each source record, the runner calls apply_lens and then apply_lens_put. Holds means that all three records round-tripped exactly. It supports a claim about this corpus; it is not a proof over every possible record.

Distinguish a finding from a failure

A counterexample produces a typed verification with result = Falsified. That finding is a successful verifier run and can be published. Transport, schema-loading, and malformed-input problems instead return VerifyError, because the runner could not evaluate the property.

The verification value is already shaped like a dev.idiolect.verification record. Chapter 5 publishes a recommendation that identifies the same lens and the source schema under which it applies.