Extend IterableOnce in FactTable and add unit tests

core-v1/src/main/scala/data/FactTable.scala

@@ -14,7 +14,7 @@ import scala.collection.immutable.SortedMap
   *
   * @note some expressions can update the fact table for sub-expressions.
   */
-trait FactTable extends Any {
+trait FactTable extends Any with IterableOnce[Fact] {
   protected type Self <: FactTable
 
   protected def build(factsByName: SortedMap[String, FactSet]): Self
@@ -44,6 +44,8 @@ trait FactTable extends Any {
     matchingFacts.reduceOption(_ | _).map(TypedFactSet.from).getOrElse(Set.empty)
   }
 
+  final override def iterator: Iterator[Fact] = factsByName.valuesIterator.flatMap(_.iterator)
+
   // TODO: Better support for formatting here
   override def toString: String = if (factsByName.isEmpty) "FactTable.empty" else {
     val factMap = factsByName.iterator.map {

core-v1/src/test/scala/data/FactTableSpec.scala

@@ -0,0 +1,30 @@
+package com.rallyhealth.vapors.v1
+
+package data
+
+import munit.FunSuite
+
+import java.time.LocalDate
+
+class FactTableSpec extends FunSuite {
+
+  import example.FactTypes._
+
+  test("FactTable.iterator removes duplicates") {
+    val allFacts = Seq[Fact](Age(23), Age(23), DateOfBirth(LocalDate.now()))
+    val factTable = FactTable(allFacts)
+    assertEquals(factTable.iterator.toSeq.sorted, allFacts.distinct.sorted)
+  }
+
+  test("FactTable.toSet") {
+    val allFacts = Seq[Fact](Age(23), DateOfBirth(LocalDate.now()), Age(24))
+    val factTable = FactTable(allFacts)
+    assertEquals(factTable.iterator.toSet, allFacts.toSet)
+  }
+
+  test("FactTable.toSeq") {
+    val allFacts = Seq[Fact](Age(23), DateOfBirth(LocalDate.now()), Age(24))
+    val factTable = FactTable(allFacts)
+    assertEquals(factTable.iterator.toSeq.sorted, allFacts.sorted)
+  }
+}