adds powerset test

src/main/kotlin/unibz.cs.semint.kprime/domain/ddl/Schema.kt

@@ -82,13 +82,13 @@ class Schema () {
 
     companion object {
 
-        fun <T> reducedPowerSet(originalSet: Set<T>): Set<Set<T>> {
+        private fun <T> reducedPowerSet(originalSet: Set<T>): Set<Set<T>> {
             var result = powerSet(originalSet)
             result = result.minus(HashSet<T>()) as Set<Set<T>>
             return result
         }
 
-        private fun <T> powerSet(originalSet: Set<T>): Set<Set<T>> {
+        fun <T> powerSet(originalSet: Set<T>): Set<Set<T>> {
             val sets = HashSet<Set<T>>()
             if (originalSet.isEmpty()) {
                 sets.add(HashSet<T>())
@@ -107,7 +107,6 @@ class Schema () {
             return sets
         }
 
-
         fun superkeys(attrs: Set<Column>, fds:Set<Constraint>): Set<Set<Column>> {
             val keys = HashSet<Set<Column>>()
             val  powerset = reducedPowerSet(attrs)

src/test/kotlin/unibz.cs.semint.kprime/domain/SchemaTest.kt

@@ -82,4 +82,27 @@ class SchemaTest {
         val setB = Constraint.set("A-->C,D; E-->A,H")
         assertTrue(Schema.equivalent(setA,setB))
     }
+
+
+    @Test
+    fun test_powerset() {
+        // given
+        val attrs = Column.set("A,B,C")
+        val notin = Column.set("D,E")
+        val fds = Constraint.set("A-->B,C;C,D-->E;E-->A;B-->D")
+        // when
+        val powerSet = Schema.powerSet(attrs)
+        // then
+        val map = HashMap<Set<Column>,Set<Column>>()
+        for (sa in powerSet) {
+            map.put(sa,Schema.closure(sa,fds))
+        }
+        for (k in map.keys) {
+            var v = map.get(k)
+            if (v!=null) {
+                v = v.minus(notin)
+                println(" $k = $v ")
+            }
+        }
+    }
 }
\ No newline at end of file