I've created a domain class in Grails like this:

class MyObject {
    static hasMany = [tags: String]
    // Have to declare this here, as nullable constraint does not seem to be honoured
    Set tags = new HashSet() 

    static constraints = {
        tags(nullable: false)
    }
}

Writing unit tests to check the size and content of the MyObject.tags property, I found I had to do the following:

assertLength(x, myObject.tags as Object[])
assertEquals(new HashSet([...]), myObject.tags)

To make the syntax nicer for writing the tests, I implemented the following methods:

void assertEquals(List expected, Set actual) {
    assertEquals(new HashSet(expected), actual)
}

void assertLength(int expected, Set set) {
    assertLength(expected, set as Object[])
}

I can now call the assertLength() and assertEquals() methods directly on an instance of Set, e.g. assertLength(x, myObject.tags) assertEquals([...], myObject.tags)

I'm new to Groovy and Grails, so unaware how dangerous method overloading like this is. Is it safe? If so, I'm slightly* surprised that these methods (or similar) aren't already available - please let me know if they are.

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* I can see how these methods could also introduce ambiguity if people weren't expecting them. E.g. assertLength(1, set) always passes, no matter what the content of set