From c297f2f2ca7d6bd21d9e79fddff4633b4995947a Mon Sep 17 00:00:00 2001
From: Pat Garrity <pfm@garrity.co>
Date: Mon, 26 Jan 2026 03:03:36 +0000
Subject: [PATCH] (patch) fix incoming algorithm -- inverted boolean (#7)

Reviewed-on: https://git.garrity.co/garrity-software/gs-graph/pulls/7
---
 .../main/scala/gs/graph/v0/Adjacency.scala    |  2 +-
 .../scala/gs/graph/v0/AdjacencyTests.scala    | 27 +++++++++++++++++++
 2 files changed, 28 insertions(+), 1 deletion(-)
 create mode 100644 modules/core/src/test/scala/gs/graph/v0/AdjacencyTests.scala

diff --git a/modules/core/src/main/scala/gs/graph/v0/Adjacency.scala b/modules/core/src/main/scala/gs/graph/v0/Adjacency.scala
index bc4966a..afd3666 100644
--- a/modules/core/src/main/scala/gs/graph/v0/Adjacency.scala
+++ b/modules/core/src/main/scala/gs/graph/v0/Adjacency.scala
@@ -32,7 +32,7 @@ final class Adjacency(val neighbors: Vector[Vector[Vertex]]):
     if vertex.ordinal >= neighbors.length then Vector.empty
     else
       neighbors.zipWithIndex
-        .filterNot {
+        .filter {
           // ignore the neighbors of the input vertex
           case (_, index) => index != vertex.ordinal
         }
diff --git a/modules/core/src/test/scala/gs/graph/v0/AdjacencyTests.scala b/modules/core/src/test/scala/gs/graph/v0/AdjacencyTests.scala
new file mode 100644
index 0000000..57fbfed
--- /dev/null
+++ b/modules/core/src/test/scala/gs/graph/v0/AdjacencyTests.scala
@@ -0,0 +1,27 @@
+package gs.graph.v0
+
+class AdjacencyTests extends munit.FunSuite:
+
+  test("should provide incoming") {
+    val N  = Size(7)
+    val vs = (0 until N.value).map(Vertex(_)).toArray
+    val E  = List(
+      Edge(vs(0), vs(1)),
+      Edge(vs(0), vs(2)),
+      Edge(vs(0), vs(3)),
+      Edge(vs(1), vs(4)),
+      Edge(vs(2), vs(4)),
+      Edge(vs(3), vs(4)),
+      Edge(vs(3), vs(5)),
+      Edge(vs(4), vs(6))
+    )
+    val A = Adjacency.fromDirectedEdges(N, E)
+
+    assertEquals(A.incoming(vs(0)), Vector.empty)
+    assertEquals(A.incoming(vs(1)), Vector(vs(0)))
+    assertEquals(A.incoming(vs(2)), Vector(vs(0)))
+    assertEquals(A.incoming(vs(3)), Vector(vs(0)))
+    assertEquals(A.incoming(vs(4)), Vector(vs(1), vs(2), vs(3)))
+    assertEquals(A.incoming(vs(5)), Vector(vs(3)))
+    assertEquals(A.incoming(vs(6)), Vector(vs(4)))
+  }