Test Firebase security rules without connecting to Firebase.
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dinoboff chore: group mocha options into test/mocha.opts
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Completely and thoroughly test your Firebase security rules without connecting to Firebase.


All you need to do is supply the security rules and some mock data, then write tests describing the expected behavior of the rules. Targaryen will interpret the rules and run the tests.

const assert = require('assert');
const targaryen = require('targaryen');

const rules = {
  rules: {
    foo: {
      '.write': 'true'
const data = {foo: 1};
const auth = {uid: 'someuid'};

const database = targaryen.database(rules, data).as(auth).with({debug: true});
const {allowed, newDatabase, info} = database.write('/foo', 2);

console.log('Rule evaluations:\n', info);

assert.equal(newDatabase.rules, database.rules);
assert.equal(newDatabase.root.foo.$value(), 2);
assert.equal(newDatabase.auth, auth);

Targaryen provides three convenient ways to run tests:

  • as a standalone command-line utility:

    targaryen path/to/rules.json path/to/tests.json
  • as a set of custom matchers for Jasmine:

    const targaryen = require('targaryen/plugins/jasmine');
    const rules = targaryen.json.loadSync(RULES_PATH);
    describe('my security rules', function() {
      beforeEach(function() {
      it('should allow authenticated user to read all data', function() {
        expect({uid: 'foo'}).canRead('/');
  • as a plugin for Chai.

    const chai = require('chai');
    const targaryen = require('targaryen/plugins/chai');
    const expect = chai.expect;
    const rules = targaryen.json.loadSync(RULES_PATH);
    describe('my security rules', function() {
      before(function() {
      it('should allow authenticated user to read all data', function() {
        expect({uid: 'foo'}).can.read.path('/');
  • or as a set of custom matchers for Jest:

    const targaryen = require('targaryen/plugins/jest');
    const rules = targaryen.json.loadSync(RULES_PATH);
      toAllowRead: targaryen.toAllowRead,
      toAllowUpdate: targaryen.toAllowUpdate,
      toAllowWrite: targaryen.toAllowWrite
    describe('my security rules', function() {
      const database = targaryen.getDatabase(rules, require(DATA_PATH));
      it('should allow authenticated user to read all data', function() {
        expect(database.as({uid: 'foo'})).toAllowRead('/');

When a test fails, you get detailed debug information that explains why the read/write operation succeeded/failed.

See USAGE.md for more information.

How does Targaryen work?

Targaryen statically analyzes your security rules using esprima. It then conducts two passes over the abstract syntax tree. The first pass, during the parsing process, checks the types of variables and the syntax of the rules for correctness. The second pass, during the testing process, evaluates the expressions in the security rules given a set of state variables (the RuleDataSnapshots, auth data, the present time, and any wildchildren).


npm install targaryen@3


  • targaryen.database(rules: object|Ruleset, data: object|DataNode, now: null|number): Database

    Creates a set of rules and initial data to simulate read, write and update of operations.

    The Database objects are immutable; to get an updated Database object with different the user auth data, rules, data or timestamp, use its with(options) method.

  • Database.prototype.with({rules: {rules: object}, data: any, auth: null|object, now: number, debug: boolean}): Database

    Extends the database object with new rules, data, auth data, or time stamp.

  • Database.prototype.as(auth: null|object): Database

    Extends the database object with auth data.

  • Database.prototype.read(path: string, options: {now: number, query: object}): Result

    Simulates a read operation.

  • Database.prototype.write(path: string, value: any, options: {now: number, priority: any}): Result

    Simulates a write operation.

  • Database.prototype.update(path: string, patch: object, options: {now: number}): Result

    Simulates an update operation (including multi-location update).

  • Result: {path: string, auth: any, allowed: boolean, info: string, database: Database, newDatabase: Database, newValue: any}

    It holds:

    • path: operation path;
    • auth: operation authentication data;
    • type: operation authentication type (read|write|patch);
    • allowed: success status;
    • info: rule evaluation info;
    • database: original database.

    For write and update operations, it also includes:

    • newDatabase: the resulting database;
    • newValue: the value written to the database.
  • targaryen.store(data: object|DataNode, options: {now: number|null, path: string|null, priority: string|number|null}): DataNode

    Can be used to create the database root ahead of time and check its validity.

    The path option defines the relative path of the data from the root; e.g. targaryen.store(1, {path: 'foo/bar/baz'}) is equivalent to targaryen.store({foo: {bar: {baz: 1}}}).

  • targaryen.store(rules: object|Ruleset): Ruleset

    Can be used to create the database rule set ahead of time and check its validity.

  • targaryen.util

    Set of helper functions used by the jasmine and chai plugins reference implementations.

Why is it named Targaryen?

There were trials. Of a sort. Lord Rickard demanded trial by combat, and the king granted the request. Stark armored himself as for battle, thinking to duel one of the Kingsguard. Me, perhaps. Instead they took him to the throne room and suspended him from the rafters while two of Aerys's pyromancers kindled a flame beneath him. The king told him that fire was the champion of House Targaryen. So all Lord Rickard needed to do to prove himself innocent of treason was... well, not burn.

George R.R. Martin, A Clash of Kings, chapter 55, New York: Bantam Spectra, 1999.