react-native-firebase/bridge/e2e/database/transactions.e2e.js

const { setDatabaseContents } = TestHelpers.database;

// TODO use testRunId in refs to prevent multiple test instances interfering with each other
describe('database()', () => {
  before(() => setDatabaseContents());
  describe('ref.transaction()', () => {
    it('increments a value', async () => {
      let valueBefore = 1;
      const ref = firebase.database().ref('tests/transaction');

      const { committed, snapshot } = await ref.transaction(currentData => {
        if (currentData === null) {
          return valueBefore + 10;
        }
        valueBefore = currentData;
        return valueBefore + 10;
      }, true);

      should.equal(committed, true, 'Transaction did not commit.');
      snapshot.val().should.equal(valueBefore + 10);
    });

    it('aborts if undefined returned', async () => {
      const ref = firebase.database().ref('tests/transaction');

      const { committed } = await ref.transaction(() => undefined, true);
      should.equal(
        committed,
        false,
        'Transaction committed and did not abort.'
      );
    });
  });
});