Ledger API Test Tool

The Ledger API Test Tool is a command line tool for testing the correctness of implementations of the Ledger API, i.e. DAML ledgers. For example, it will show you if there are consistency or conformance problem with your implementation.

Its intended audience are developers of DAML ledgers, who are using the DAML Ledger Implementation Kit to develop a DAML ledger on top of their distributed-ledger or database of choice.

Use this tool to verify if your Ledger API endpoint conforms to the DA Ledger Model.

Please note that currently the tool is in ALPHA status:

  • ALPHA: contains a subset of the tests we use internally to test our ledger implementations.
  • BETA: will be reached once we extended the coverage to include the full set of our test as per <https://github.com/digital-asset/daml/issues/146>.

Downloading the tool

Run the following command to fetch the tool:

curl -L 'https://bintray.com/api/v1/content/digitalassetsdk/DigitalAssetSDK/com/daml/ledger/testtool/ledger-api-test-tool_2.12/$latest/ledger-api-test-tool_2.12-$latest.jar?bt_package=sdk-components' -o ledger-api-test-tool.jar

This will create a file ledger-api-test-tool.jar in your current directory.

Extracting .dar files required to run the tests

Before you can run the Ledger API test tool on your ledger, you need to load a specific set of DAML templates onto your ledger.

  1. To obtain the corresponding .dar files, run:

    $ java -jar ledger-api-test-tool.jar --extract
    

    This writes all .dar files required for the tests into the current directory.

  2. Load all .dar files into your Ledger.

Running the tool against a custom Ledger API endpoint

Run this command to test your Ledger API endpoint exposed at host <host> and at a port <port>:

$ java -jar ledger-api-test-tool.jar  -h <host> -p <port>

For example

$ java -jar ledger-api-test-tool.jar  -h localhost -p 6865

If any test embedded in the tool fails, it will print out details of the failure for further debugging.

Exploring options the tool provides

Run the tool with --help flag to obtain the list of options the tool provides:

$ java -jar ledger-api-test-tool.jar  --help

Selecting tests to run

Running the tool without any arguments runs the default tests. Use the following command line flags to select which tests to run:

  • --list: print all available tests to the console
  • --include: only run the tests provided as argument
  • --exclude: do not run the tests provided as argument
  • --all-tests: run all default and optional tests. This flag can be combined with the --exclude flag.

Examples:

Only run TestA
$ java -jar ledger-api-test-tool.jar --include TestA
Run all default tests, but not TestB
$ java -jar ledger-api-test-tool.jar --exclude TestB
Run all tests
$ java -jar ledger-api-test-tool.jar --all-tests
Run all tests, but not TestC
$ java -jar ledger-api-test-tool.jar --all-tests --exclude TestC

Try out the Ledger API Test Tool against DAML Sandbox

If you wanted to test out the tool, you can run it against DAML Sandbox. To do this:

$ java -jar ledger-api-test-tool.jar --extract
$ da sandbox -- *.dar
$ java -jar ledger-api-test-tool.jar

This should always succeed, as the Sandbox is tested to correctly implement the Ledger API. This is useful if you do not have yet a custom Ledger API endpoint.

You don’t need to supply the hosts and ports arguments, because the Ledger API Test Tool defaults to using localhost:6865, which the Sandbox uses by default.

Testing your tool from continuous integration pipelines

To test your ledger in a CI pipeline, run it as part of your pipeline:

$ java -jar ledger-api-test-tool 2>&1 /dev/null
$ echo $?
0

The tool is tailored to be used in CI pipelines: as customary, when the tests succeed, it will produce minimal output and return the success exit code.

Using the tool with a known-to-be-faulty Ledger API implementation

Use flag --must-fail if you expect one or more or the scenario tests to fail. If enabled, the tool will return the success exit code when at least one test fails, and it will return a failure exit code when all tests succeed:

java -jar ledger-api-test-tool.jar --must-fail -h localhost -p 6865

This is useful during development of a DAML ledger implementation, when tool needs to be used against a known-to-be-faulty implementation (e.g. in CI). It will still print information about failed tests.

We used this flag during tool development to ensure that the tool does not always return success.

Tuning the testing behaviour of the tool

Use the command line options --timeout-scale-factor and --command-submission-ttl-scale-factor to tune timeouts applied by the tool.

  • Set --timeout-scale-factor to a floating point value higher than 1.0 to make the tool wait longer for expected events coming from the DAML ledger implementation under test. Conversely use values smaller than 1.0 to make it wait shorter.
  • Set --command-submission-ttl-scale-factor to a value higher than 1.0 to make the test tool generate Ledger API Commands with higher than default maximum record time, which might be necessary for DAML ledger implementations which take a long time to commit a proposed transaction. Conversely use values smaller than 1.0 to make it give less time for a DAML ledger implementation to commit a proposed transaction.