spectool

March 16, 2026 · View on GitHub

A conformance testing tool for WDL (Workflow Description Language) execution engines.

Overview

spectool extracts conformance tests from the WDL specification and runs them against WDL execution engines to verify compliance with the specification. Tests are extracted from the WDL SPEC.md file and compiled into executable WDL files that can be run against any WDL engine.

Building

# Build `spectool` at `target/release/spectool`.
cargo build --release

# Install `spectool` to the path.
cargo install --path .

Usage

spectool has a number of options that allow it to call all major WDL execution engines. You can use spectool like so,

spectool test "sprocket run ~{path} ~{input} -t ~{target}" --redirect-stdout

The command template supports the following substitutions:

~{path} — path to the WDL test file
~{input} — path to the input JSON file
~{output} — path to the output JSON file
~{target} — name of the workflow or task to execute

Common Options

Specify the WDL specification directory:

spectool test "sprocket run ~{path} ~{input} -t ~{target}" --redirect-stdout -s ~/openwdl/wdl

Save compiled tests to a directory:

spectool test "sprocket run ~{path} ~{input} -t ~{target}" --redirect-stdout -c ./conformance-tests

Filter tests by name:

# Run only tests matching "array"
spectool test "sprocket run ~{path} ~{input} -t ~{target}" --include array

# Exclude tests matching "fail"
spectool test "sprocket run ~{path} ~{input} -t ~{target}" --exclude fail

Inject a different WDL version:

# Replace version 1.2 with version development
spectool test "cromwell run ~{path} -i ~{input}" --inject-wdl-version development --redirect-stdout

Transform output JSON before validation:

# Extract .outputs field from the engine's output
spectool test "miniwdl run ~{path} -i ~{input}" --output-selector '.outputs' --redirect-stdout

Test with specific capabilities:

spectool test "..." --capabilities optional_inputs,optional_outputs

Fail with a non-zero exit code if any tests fail:

spectool test "sprocket run ~{path} ~{input} -t ~{target}" --redirect-stdout --strict

Example Workflows

Testing Cromwell

To test Cromwell, you can use the following script.

spectool test \
  "cromwell run ~{path} -i ~{input} --metadata-output ~{output}" \
  --inject-wdl-version development \
  --output-selector .outputs \
  --redirect-stdout \
  --all-capabilities

This script assumes you have cromwell installed using Homebrew. If you don't, you'll have to substitute the cromwell script with java -jar cromwell.jar.

Testing MiniWDL

To test MiniWDL, you can use the following script.

spectool test \
  "miniwdl run ~{path} -i ~{input}" \
  --inject-wdl-version development \
  --output-selector '.outputs' \
  --redirect-stdout \
  --all-capabilities

Testing Toil

To test Toil, you can use the following script.

spectool test \
  "toil-wdl-runner ~{path} --inputs ~{input}" \
  --inject-wdl-version development \
  --redirect-stdout \
  --all-capabilities

Testing Sprocket

To test Sprocket, you can use the following script.

spectool test \
  "sprocket run ~{path} ~{input} -t ~{target}" \
  --redirect-stdout \
  --all-capabilities

License

This tool is made available to you under the BSD 3-Clause License.