jMatch

jMatch is a testsuite for JSON/YAML files. It allows you to check these files against a specification based on defined patterns. This is useful if you need to check lots of JSON files or if you want to check your JSON files in a continuous integration pipeline.

Table of Contents

• Installation
• Usage
• Support

Installation

Install via PIP

Make sure, you have python3 with pip installed. Use pip to install jMatch in your shell as follows:

pip install jmatch

Usage

As soon as jMatch is installed, it is used to check JSON/YAML documents against a predefined specification. jMatch uses JSON/YAML to define specification options as a search pattern.

Example Specification Pattern

Example usecase: Imagine, a bunch of JSON-formated config files, all of those config files should specify the same text-encoding (UTF-8) to make sure that all systems interoperate correctly.

Solution: To implement a solution for the given usecase, another JSON-document needs to be specified, which contains at least the following data concerning the given problem.

• type: info or error
• message: A message to print if the pattern matches
• pattern: An info or error case pattern that is searched in the document to check.

[{
  "_type": "error",
  "_message": "The encoding should be UTF-8, but it is not.",
  "_pattern": {
    "encoding": {"_not": "UTF-8"}
  }
}]

We want to mark the problem as critical, we use the error type. If used in a CI-pipeline, the type error forces the Pipeline to fail, if the pattern matches. For the pattern we want to search for a encoding, with a value different from UTF-8.

Check if the pattern exists in a JSON document

If we want to check a configfile.json file if it matches our check-encoding-utf8.json. We can perform the following operation, assuming that both files are in our current working directory:

jmatch --target configfile.json check-encoding-utf8.json

If the configfile contains the pattern specified in check-encoding-utf8.json, the _message specified is displayed.

Check for multiple patterns at once

jMatch allows to check many patterns at once, therefore all pattern files must be provided when running jMatch.

jmatch --target configfile.json pattern1.json pattern2.json [...]

To provide multiple pattern files for jMatch, wildcard expressions can be used, to specify many pattern files easily:

jmatch --target hello.json pattern*.json

Flags

There are many different flags which change jMatchs default behavior. You can use the --help flag to show all available options.

Support

Please open an issue for support.