json-schema-testgen

Generate test files from the official JSON-Schema-Test-Suite for validating JSON Schema implementations.

Supports generating tests for Bun, Vitest, and Jest.

Usage

# With npx
npx json-schema-testgen --help

# With bunx
bunx json-schema-testgen --help

Generating tests

# Generate required tests for all drafts (default runner: bun)
npx json-schema-testgen

# Generate tests for vitest or jest
npx json-schema-testgen --runner vitest
npx json-schema-testgen --runner jest

# Generate only specific drafts
npx json-schema-testgen --drafts draft7,draft2020-12

# Include optional tests
npx json-schema-testgen --include-optional

# Custom output directory
npx json-schema-testgen --output ./my-tests

CLI options

| Option | Description | Default | |---|---|---| | --runner <runner> | Test runner: bun, vitest, jest | bun | | --drafts <list> | Comma-separated drafts to include | all drafts | | --include-optional | Include optional tests | false | | --output <dir> | Output directory | ./generated-tests | | --version | Show version | | | --help | Show help message | |

Plugging in your validator

Create a setup file that calls setValidator before tests run:

import { setValidator } from "json-schema-testgen";

setValidator((schema, data, draft) => {
  // Return { valid: boolean, errors?: string[] }
  // `draft` is e.g. "draft7", "draft2020-12"
  const result = myValidator.validate(schema, data);
  return { valid: result.valid, errors: result.errors };
});

How you preload the setup file depends on the runner:

• Bun — add preload = ["./setup.ts"] to bunfig.toml, then bun test
• Vitest — add setupFiles: ["./setup.ts"] to your vitest config, then vitest
• Jest — add setupFilesAfterFramework: ["./setup.ts"] to your jest config, then jest

Supported drafts

• draft3
• draft4
• draft6
• draft7
• draft2019-09
• draft2020-12

Test output

Generated tests show verbose details on failure:

Schema: {
  "type": "integer"
}
Data:   1.1
Expected: invalid
Got:      valid
Errors: type mismatch: expected integer

Development

bun install
git submodule update --init   # fetch the official test suite
bun run build-data            # embed test data into src/test-data.ts

To update when the upstream test suite changes:

cd official-tests && git pull origin main && cd ..
bun run build-data