Grails and Hibernate Plugin

Question

I am quite new to Grails, and I am on version 2.2.4. I got some tests I want to run:

package racetrack

import grails.test.mixin.*
import org.junit.*

/**
 * See the API for {@link grails.test.mixin.domain.DomainClassUnitTestMixin} for usage instructions
 */
@TestFor(User)
class UserTests {

  void testSomething() {
    // fail "Implement me"
  }

  void testSimpleContraints(){
    mockForConstraintsTests(User)
    def user = new User(login:"someone",
      password:"blah",
      role:"SuperUser")
    assertFalse user.validate()
    assertEquals "inList", user.errors["role"]
  }
}

and the test seems to be running although the last one fails, but I get this at the end:

| Error Error loading plugin manager: Could not create a new instance of class [HibernateGrailsPlugin]! (Use --stacktrace to see the full trace)

Even if I remove the above test I get the same thing. I dont know if it is relevant but I got this in my BuildConfig.groovy file:

grails.servlet.version = "2.5" // Change depending on target container compliance (2.5 or 3.0)
grails.project.class.dir = "target/classes"
grails.project.test.class.dir = "target/test-classes"
grails.project.test.reports.dir = "target/test-reports"
grails.project.target.level = 1.6
grails.project.source.level = 1.6
//grails.project.war.file = "target/${appName}-${appVersion}.war"

// uncomment (and adjust settings) to fork the JVM to isolate classpaths
//grails.project.fork = [
//   run: [maxMemory:1024, minMemory:64, debug:false, maxPerm:256]
//]

grails.project.dependency.resolution = {
    // inherit Grails' default dependencies
    inherits("global") {
        // specify dependency exclusions here; for example, uncomment this to disable ehcache:
        // excludes 'ehcache'
    }
    log "error" // log level of Ivy resolver, either 'error', 'warn', 'info', 'debug' or 'verbose'
    checksums true // Whether to verify checksums on resolve
    legacyResolve false // whether to do a secondary resolve on plugin installation, not advised and here for backwards compatibility

    repositories {
        inherits true // Whether to inherit repository definitions from plugins

        grailsPlugins()
        grailsHome()
        grailsCentral()

        mavenLocal()
        mavenCentral()

        // uncomment these (or add new ones) to enable remote dependency resolution from public Maven repositories
        //mavenRepo "http://snapshots.repository.codehaus.org"
        //mavenRepo "http://repository.codehaus.org"
        //mavenRepo "http://download.java.net/maven/2/"
        //mavenRepo "http://repository.jboss.com/maven2/"
    }

    dependencies {
        // specify dependencies here under either 'build', 'compile', 'runtime', 'test' or 'provided' scopes e.g.

        // runtime 'mysql:mysql-connector-java:5.1.22'
    }

    plugins {
        runtime ":hibernate:$grailsVersion"
        runtime ":jquery:1.8.3"
        runtime ":resources:1.2"

        // Uncomment these (or add new ones) to enable additional resources capabilities
        //runtime ":zipped-resources:1.0"
        //runtime ":cached-resources:1.0"
        //runtime ":yui-minify-resources:0.1.5"

        build ":tomcat:$grailsVersion"

        runtime ":database-migration:1.3.2"

        compile ':cache:1.0.1'
    }
}

Any help plox?