@json-schema-org/tests

@json-schema-org/tests

NPM / node.js-specific support for the JSON Schema test suite

The JSON Schema Test Suite is meant to be a language agnostic test suite for testing JSON Schema validation libraries. It is generally added to projects as a git submodule. However, to simplify things for Node.js developers, the test suite has also been made available as an npm package.

npm install @json-schema-org/tests

Usage:

There are a number of ways to load tests from the suite:

const testSuite = require('@json-schema-org/tests');

// this will load all (required and optional) draft6 tests
const tests = testSuite.loadSync();

// optional `filter` is a function that takes 3 arguments (filename, parent, optional)
// and returns true if the test should be included. The optional argument is true
// for all files under the `<draft>/optional` directory.
// optional `draft` should be either `'draft3'`, `'draft4'` or `'draft6'`

const tests = testSuite.loadSync(filter, draft);

// convenience functions:

// The following take an optional `filter` as described previously (undefined will load all tests)
const draft3 = testSuite.draft3();
const draft4 = testSuite.draft4();
const draft6 = testSuite.draft6();

// The following take an optional `draft` argument (defaults to 'draft6')
const all = testSuite.loadAllSync();
const required = testSuite.loadRequiredSync();
const optional = testSuite.loadOptionalSync();

The return value of these functions is an array of objects that correspond to each file under tests/<draft> that passed the filter (the default is all, so the array will also include all the optional files).

Each object has the following structure (using tests/draft4/additionalItems.json as an example):

{
  name:    'additionalItems',
  file:     'additionalItems.json',
  optional: false,  // true if a file under the optional directory
  schemas:  []
}

The schemas property contains the array of objects loaded from the test file. Each object consists of a schema and description, along with a number of tests used for validation. Using the first schema object in the array from tests/draft4/additionalItems.json as an example:

{
  description: 'additionalItems as schema',
  schema: {
    items: [{}],
    additionalItems: { type: "integer" }
  },
  tests: [
    {
      description: "additional items match schema",
      data: [ null, 2, 3, 4 ],
      valid: true
    },
    {
      description: "additional items do not match schema",
      data: [ null, 2, 3, "foo" ],
      valid: false
    }
  ]
}

Testing a JSON Validator

You can apply a validator against all the tests. You need to create a validator factory function that takes a JSON schema and an options argument, and returns an object with a validate method. The validate function should take a JSON object to be validated against the schema. It should return an object with a valid property set to true or false, and if not valid, an errors property that is an array of one or more validation errors.

The following are examples of Tiny Validator (tv4) and z-schema validator factories used by the unit test.

tv4

const tv4 = require('tv4');

const tv4Factory = function (schema, options) {
  return {
    validate: function (json) {
      try {
        const valid = tv4.validate(json, schema);
        return valid ? { valid: true } : { valid: false, errors: [ tv4.error ] };
      } catch (err) {
        return { valid: false, errors: [err.message] };
      }
    }
  };
};

ZSchema

const ZSchema = require('z-schema');

const zschemaFactory = function (schema, options) {
  const zschema = new ZSchema(options);

  return {
    validate: function (json) {
      try {
        const valid = zschema.validate(json, schema);
        return valid ? { valid: true } : { valid: false, errors: zschema.getLastErrors() };
      } catch (err) {
        return { valid: false, errors: [err.message] };
      }
    }
  };
};

Testing the Validator

Using a validator factory as described above, you can test it as follows.

const testSuite = require('json-schema-test-suite');

const tests = testSuite.testSync(factory);

The tests return value is as described previously in the Usage section, with an additional property for each test object that corresponds to the test result:

{
  description: 'additionalItems as schema',
  schema: {
    items: [{}],
    additionalItems: { type: "integer" }
  },
  tests: [
    {
      description: "additional items match schema",
      data: [ null, 2, 3, 4 ],
      valid: true,
      result: {
        valid: false,
        errors: [ ... ]
      }
    },
    {
      description: "additional items do not match schema",
      data: [ null, 2, 3, "foo" ],
      valid: false,
      result: {
        true
      }
    }
  ]
}

Tests

You can run the tests by doing:

npm test