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    1.3.1 • Public • Published


    This package provides the assertion testing functionality for the Web of Things Playground. You can find more information about the Thingweb-Playground here.

    Validation tool for W3C WoT Thing Descriptions. Your Thing Descriptions should be written according to the W3C standard found here.


    • There is limited nested validation. This is due to the JSON Schema specification which doesn't allow infinite references with $ref keywords. Because of this, an enum key in a e.g. #/actions/input/properties/enum will not be necessarily checked. More information can be found here.


    You can use this package to integrate TD assertion testing in your own Browser/NPM application.

    • Install this package via NPM (npm install @thing-description-playground/assertions) (or clone repo and install the package with npm install)

    • Node.js or Browser import:

      • Node.js: Require the package and use the assertion Testing function
      const tdAssertions = require("@thing-description-playground/assertions")
      • Browser: Import the tdAssertions function as a global by adding a script tag to your html.
      <script src="./node_modules/@thing-description-playground/assertions/dist/web-bundle.min.js"></script>
    • Now you can call the assertion testing function and handle the result.

      tdAssertions([simpleTD], fileLoad, /*OPT: log Function*/, /*OPT: manual report*/)
      .then( result => {
      }, err => {

      You can also find examples on how to use this package in the example-scripts folder or the web and cli packages.


    • index.js contains the package import/export structure, application flow (assertion testing, merging, print stats), and handles loading of the assertion schemas
    • assertionTests.js contains the actual assertion testing functionalities
    • checkCoverage.js can output stats about a given assertion testing report
    • list.json a list of all filenames in the assertions folder. Required, for browser usage of the package (since no access to ddirectory content exists there).
    • manual.csv example of a manual report part. Used if no other file is specified as manual assertion report.
    • mergeResults.js can merge several assertion testing reports to one single report, representing the assertions results of an whole implementation instead of single TDs.
    • update-list.js Has to be executed after applying changes of files in the assertions directory. Updates the list.json with the current filenames.


    Licensed under the MIT license, see License.

    Script based Thing Description Validation

    This is a Node.js based tool.

    • You can use core package as an API to validate TDs in your own packages.
    • You can use the cli package to test one/multiple TDs via the command line.
    • You can use this package to integrate assertion testing via an API in your own packages.
    • You can use the web package to host/adapt your own browser version of the WoT playground. Remember you need to deliver its files by a web server (also locally possible via localhost), simply opening the index.html with a browser won't do the job.

    Script based Assertion Tester

    297 out of 349 assertions of the TD specification can be tested with this tool.

    This tool checks which assertions are satisfied by a given Thing Description(s). The assertions are modeled as JSON Schema or as scripts. 'AssertionTester/Assertions' has the JSON Schema assertions.

    To use the assertion testing via the command line please use the cli package.

    WARNING: If you see an error like ajv.errors[0].params.allowedValue this very probably means that your TD is not valid at a specific point. Scroll up to see the precise error message


    You can contribute by providing new JSON Schemas for assertions or by correcting them. There are two types of assertions:

    • Not-complex: This is generally used to check assertions that are in the Thing instance or mandatory assertions. You simply put the JSON key to be checked in the required validation keyword.

    • Complex: This type uses the if-then-else structure of JSON Schema Draft 7. You should put an if for the keyword you want to check and the following object in the then:

        "then": {
            "const": "td-data-schema_description=pass"

      This way, the validation will surely fail at the const keyword and display that the JSON data has to be "td-data-schema_description=pass" string. This will be then detected by the assertion testing tool which will look for the = sign to find the result. If the schema doesn't fail, it implies that this if was false, which in turn implies that the assertion you wanted to test was not implemented in the given TD.

    Known Bugs




    npm i @thing-description-playground/assertions

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