No transactionManager error in Grails 3 Integration test

I have created a new Grails 3.1.4 angular project along with a few domain objects and controllers extending RestfulController. I have created the Integration test below. When I run grails test-app -integration I get the error

java.lang.IllegalStateException: No transactionManager was specified. Using @Transactional or @Rollback requires a valid configured transaction manager. If you are running in a unit test ensure the test has been properly configured and that you run the test suite not an individual test method.
    at grails.transaction.GrailsTransactionTemplate.<init>(GrailsTransactionTemplate.groovy:60)
    at com.waldoware.invoicer.BillingEntityRestControllerIntegrationSpec.$tt__$spock_feature_0_0(BillingEntityRestControllerIntegrationSpec.groovy:29)
    at com.waldoware.invoicer.BillingEntityRestControllerIntegrationSpec.test all entities_closure2(BillingEntityRestControllerIntegrationSpec.groovy)
    at groovy.lang.Closure.call(Closure.java:426)
    at groovy.lang.Closure.call(Closure.java:442)
    at grails.transaction.GrailsTransactionTemplate$1.doInTransaction(GrailsTransactionTemplate.groovy:70)
    at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:133)
    at grails.transaction.GrailsTransactionTemplate.executeAndRollback(GrailsTransactionTemplate.groovy:67)
    at com.waldoware.invoicer.BillingEntityRestControllerIntegrationSpec.test all entities(BillingEntityRestControllerIntegrationSpec.groovy)

Test class:

package com.waldoware.invoicer

import grails.test.mixin.integration.Integration
import grails.transaction.*
import spock.lang.*

@Integration
@Rollback
class BillingEntityRestControllerIntegrationSpec extends Specification {

    def setupData() {
        def biller = new BillingEntity()
        biller.with {
            companyName = "Acme, Inc."
        }
        def ledger = new Ledger(name: "My Ledger", billingEntity: biller).save(failOnError: true, flush: true)
    }

    void 'test all entities'() {
        when:
        setupData()
        new BillingEntityRestController().index()

        then:
        response.contentType == 'application/json;charset=UTF-8'
        response.status == HttpServletResponse.SC_OK
        response.text == "[{}]"
    }
}