[S2GRAPH-171]: Support "undirected" label's direction when create Edge

s2core/src/main/scala/org/apache/s2graph/core/GraphElementBuilder.scala

@@ -69,7 +69,7 @@ class GraphElementBuilder(graph: S2GraphLike) {
     val (ts, operation, logType, srcId, tgtId, label) = (parts(0), parts(1), parts(2), parts(3), parts(4), parts(5))
     val props = if (parts.length >= 7) fromJsonToProperties(Json.parse(parts(6)).asOpt[JsObject].getOrElse(Json.obj())) else Map.empty[String, Any]
     val tempDirection = if (parts.length >= 8) parts(7) else "out"
-    val direction = if (tempDirection != "out" && tempDirection != "in") "out" else tempDirection
+    val direction = if (tempDirection != "out" && tempDirection != "in" && tempDirection != "undirected") "out" else tempDirection
     val edge = toEdge(srcId, tgtId, label, direction, props, ts.toLong, operation)
     Option(edge)
   } recover {

s2core/src/test/scala/org/apache/s2graph/core/GraphElementBuilderTest.scala

@@ -0,0 +1,57 @@
+package org.apache.s2graph.core
+
+import org.apache.s2graph.core.mysqls.Label
+import org.scalatest._
+
+class GraphElementBuilderTest extends FunSuite with Matchers with TestCommon with TestCommonWithModels {
+  initTests()
+
+  /*
+    In Test CommonWithModels,
+      - labelName: undirectedLabelName is created as undirected label.
+      - labelName: labelName is created as directed label.
+   */
+  val timestamp = "1"
+  val operation = "insert"
+  val logType = "edge"
+  val srcId = 1L
+  val tgtId = 101L
+  val props = "{}"
+  val outDirection = "out"
+  val inDirection = "in"
+
+
+  test("toEdge with directed label. direction out.") {
+    val parts = Array(
+      timestamp, operation, logType, srcId.toString, tgtId.toString, labelName, props, outDirection
+    )
+
+    val s2EdgeLike = builder.toEdge(parts).get
+    s2EdgeLike.srcVertex.id.innerId.value shouldBe(srcId)
+    s2EdgeLike.tgtVertex.id.innerId.value shouldBe(tgtId)
+    s2EdgeLike.getDirection() shouldBe("out")
+
+  }
+  test("toEdge with directed label. direction in.") {
+    val parts = Array(
+      timestamp, operation, logType, srcId.toString, tgtId.toString, labelName, props, inDirection
+    )
+
+    val s2EdgeLike = builder.toEdge(parts).get
+    s2EdgeLike.srcVertex.id.innerId.value shouldBe(srcId)
+    s2EdgeLike.tgtVertex.id.innerId.value shouldBe(tgtId)
+    s2EdgeLike.getDirection() shouldBe("in")
+
+  }
+  test("toEdge with undirected label. direction out.") {
+    // undirectedLabelName has tgtColumnType as string.
+    val parts = Array(
+      timestamp, operation, logType, srcId.toString, tgtId.toString, undirectedLabelName, props, outDirection
+    )
+
+    val s2EdgeLike = builder.toEdge(parts).get
+    s2EdgeLike.srcVertex.id.innerId.value shouldBe(srcId)
+    s2EdgeLike.tgtVertex.id.innerId.value shouldBe(tgtId.toString)
+    s2EdgeLike.getDirection() shouldBe("out")
+  }
+}