Grails Integration test: Failure...Cannot invoke method addToPosts() on null object - grails

Question

:D
I was following a tutorial in a book, and I did follow it thoroughly.
However, come the part where I am supposed to write an integration test, it suddenly failed saying: Cannot invoke method addToPosts() on null object right after I ran the test. I wonder, what could be wrong... :| Please help! :) Below is the code for the test:
void testFirstPost() {
def user = new User(userID: 'joemillan', password:'youaretheonly',
homepage: 'www.geeee.com').save()
def post = new Post (content: 'hellloo oasdo sjdosa daodkao ')
user.addToPosts(post)
assertEquals 1, User.get(user.id).posts.size()
}
Here is the user class:
class User {
String userID
String password
String homepage
Profile profile
static hasMany=[posts:Post, tags:Tag]
static constraints = {
userID (unique: true, size: 6..20)
password (size: 6..20, validator:{password,userID-> return password !=userID.userID}) //validator = The password must not match the username.
homepage (url:true, nullable: true)
profile (nullable: true)
}
}
Here is the Post class:
class Post {
String content
Date dateCreated
static constraints = {
content (blank:false)
}
static belongsTo = [user:User]
static hasMany = [tags:Tag]
static mapping = {
sort dateCreated: "desc"
}
}

Answer 1

save() returns null if validation fails, and "www.geeee.com" isn't a valid URL. It would work with "http://www.geeee.com".
But you should split the creation and saving into 2 steps so you can check it:
def user = new User(userID: 'joemillan', password:'youaretheonly',
homepage: 'www.geeee.com')
user.save()
assertFalse user.hasErrors()
or use failOnError if you are confident that that part should succeed and only want to test the other parts, e.g.
def user = new User(userID: 'joemillan', password:'youaretheonly',
homepage: 'www.geeee.com').save(failOnError: true)