asset-tests — Daml Script unit tests with dpm trace test

A small, self-contained Daml package that shows how to run Daml Script unit tests through dpm trace test and wire it into CI/CD.

daml test runs your Script tests but only prints a coverage summary; the transaction trees go to per-script HTML files meant for the IDE, and a failing test gives you a verbose message with no rendered source. dpm trace test runs the same tests and, in the terminal and as JSON:

• renders each script's transaction tree (creates, exercises, archives, submitMustFail guard nodes, parties, arguments, source locations);
• maps every failed test back to source — the test call site and the contract invariant (assertMsg/abort/ensure) that rejected it;
• returns a non-zero exit code when any test fails, so it gates CI;
• emits a machine-readable report with --print-json and standard JUnit XML with --junit.

No Canton node is involved: daml test uses the in-memory IDE ledger, so this runs anywhere a Daml toolchain runs.

Layout

daml/Asset.daml   # an IOU-style Asset contract: Transfer, Split, Burn, ensure quantity > 0
daml/Test.daml    # Daml Script unit tests: happy paths + submitMustFail guards (the gate)
daml/FailureDemo.daml      # one deliberately failing test, to show source-mapped failures
.github/workflows/ci.yml   # GitHub Actions CI using `dpm trace test` as the gate
run-demo.sh       # green run -> inject a regression -> red run -> revert

The tests mix the cases a real suite has:

Test	What it exercises
testIssue	create, payload/observer visibility
testTransfer	consuming exercise → archive + child create
testSplit	exercise → two child creates
testCannotIssueZero	ensure quantity > 0 rejection (submitMustFail)
testStrangerCannotTransfer	authorization rejection (submitMustFail)
testBadSplitFails	in-choice assertMsg rejection (submitMustFail)

Run it

# from this directory
daml build                       # produces .daml/dist/asset-tests-1.0.0.dar (optional but recommended)

dpm trace test .                 # run every Script test, render trees, gate on failures
dpm trace test . --no-trees      # summary + failures only (compact CI logs)
dpm trace test . --print-json    # machine-readable report
dpm trace test . -p testSplit    # run a subset by pattern

If the dpm plugin is not on your PATH, run the CLI directly:

PYTHONPATH=../dpm-trace/src python3 -m dpm_trace.cli test . --daml daml

Pass --dar .daml/dist/asset-tests-1.0.0.dar to verify failure text against the compiled package with damlc inspect before resolving it against local sources.

Demo: catching a regression

./run-demo.sh shows the full story end to end: a green run, then it weakens ensure quantity > 0 to >= 0, re-runs, and the zero-quantity guard test fails with a source-mapped diagnostic and a non-zero exit code — then it reverts.

FAIL  testCannotIssueZero
      message: ... Expected submit to fail but it succeeded
      daml/Test.daml:63:3
      > 63 |   submitMustFail issuer do
               ^

CI/CD

.github/workflows/ci.yml is a complete example. The key line is just:

dpm trace test . --junit dpm-trace-results.xml --no-trees

A non-zero exit fails the job; the JUnit XML is uploaded for the test-report UI; and any failure is printed with its source location in the job log.