issubset.go

package issubset

import "reflect"

// Check to see if `expected` is a subset of `actual`. A "subset" is an object that is equivalent to
// the other object, but where map keys found in actual that are not defined in expected are ignored.
func IsSubset(expected, actual interface{}) bool {
	if reflect.TypeOf(expected) != reflect.TypeOf(actual) {
		return false
	}

	if reflect.DeepEqual(expected, actual) {
		return true
	}

	if reflect.TypeOf(expected).Kind() == reflect.Slice {
		if reflect.ValueOf(expected).Len() != reflect.ValueOf(actual).Len() {
			return false
		}

		for i := 0; i < reflect.ValueOf(expected).Len(); i++ {
			if ! IsSubset(reflect.ValueOf(expected).Index(i).Interface(), reflect.ValueOf(actual).Index(i).Interface()) {
				return false
			}
		}
	} else if reflect.TypeOf(expected).Kind() == reflect.Map {
		iter := reflect.ValueOf(expected).MapRange()

		for iter.Next() {
			actualValue := reflect.ValueOf(actual).MapIndex(iter.Key())

			if ! actualValue.IsValid() {
				return false
			}

			if ! IsSubset(iter.Value().Interface(), actualValue.Interface()) {
				return false
			}
		}
	} else {
		return false
	}

	return true
}