Add LinearBoundary unit test

modules/core/src/main/java/org/locationtech/jts/operation/relateng/LinearBoundary.java

@@ -49,6 +49,10 @@ private boolean checkBoundary(Map<Coordinate, Integer> vertexDegree) {
     return false;
   }
 
+  public boolean hasBoundary() {
+    return hasBoundary;
+  }
+
   public boolean isBoundary(Coordinate pt) {
     if (! vertexDegree.containsKey(pt))
       return false;
@@ -75,13 +79,5 @@ private static void addEndpoint(Coordinate p, Map<Coordinate, Integer> degree) {
     dim++;
     degree.put(p, dim);
   }
-
-  public Set<Coordinate> getEndPoints() {
-    return vertexDegree.keySet();
-  }
-
-  public boolean hasBoundary() {
-    return hasBoundary;
-  }
 
 }

modules/core/src/test/java/org/locationtech/jts/operation/relateng/LinearBoundaryTest.java

@@ -0,0 +1,97 @@
+/*
+ * Copyright (c) 2024 Martin Davis.
+ *
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * and Eclipse Distribution License v. 1.0 which accompanies this distribution.
+ * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v20.html
+ * and the Eclipse Distribution License is available at
+ *
+ * http://www.eclipse.org/org/documents/edl-v10.php.
+ */
+package org.locationtech.jts.operation.relateng;
+
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+import org.locationtech.jts.algorithm.BoundaryNodeRule;
+import org.locationtech.jts.geom.Coordinate;
+import org.locationtech.jts.geom.Geometry;
+import org.locationtech.jts.geom.LineString;
+import org.locationtech.jts.geom.util.LineStringExtracter;
+
+import junit.textui.TestRunner;
+import test.jts.GeometryTestCase;
+
+public class LinearBoundaryTest extends GeometryTestCase {
+  public static void main(String args[]) {
+    TestRunner.run(LinearBoundaryTest.class);
+  }
+
+  public LinearBoundaryTest(String name) {
+    super(name);
+  }
+
+  public void testLineMod2() {
+    checkLinearBoundary("LINESTRING (0 0, 9 9)", 
+        BoundaryNodeRule.MOD2_BOUNDARY_RULE,
+        "MULTIPOINT((0 0), (9 9))");   
+  }
+
+  public void testLines2Mod2() {
+    checkLinearBoundary("MULTILINESTRING ((0 0, 9 9), (9 9, 5 1))", 
+        BoundaryNodeRule.MOD2_BOUNDARY_RULE,
+        "MULTIPOINT((0 0), (5 1))");   
+  }
+
+  public void testLines3Mod2() {
+    checkLinearBoundary("MULTILINESTRING ((0 0, 9 9), (9 9, 5 1), (9 9, 1 5))", 
+        BoundaryNodeRule.MOD2_BOUNDARY_RULE,
+        "MULTIPOINT((0 0), (5 1), (1 5), (9 9))");   
+  }
+
+  public void testLines3Monvalent() {
+    checkLinearBoundary("MULTILINESTRING ((0 0, 9 9), (9 9, 5 1), (9 9, 1 5))", 
+        BoundaryNodeRule.MONOVALENT_ENDPOINT_BOUNDARY_RULE,
+        "MULTIPOINT((0 0), (5 1), (1 5))");   
+  }
+
+  private void checkLinearBoundary(String wkt, BoundaryNodeRule bnr, String wktBdyExpected) {
+    Geometry geom = read(wkt);
+    LinearBoundary lb = new LinearBoundary(extractLines(geom), bnr);
+    boolean hasBoundaryExpected = wktBdyExpected == null ? false : true;
+    assertEquals("HasBoundary", hasBoundaryExpected, lb.hasBoundary());
+
+    checkBoundaryPoints(lb, geom, wktBdyExpected);
+  }
+
+  private void checkBoundaryPoints(LinearBoundary lb, Geometry geom, String wktBdyExpected) {
+    Set<Coordinate> bdySet = extractPoints(wktBdyExpected);
+
+    for (Coordinate p : bdySet) {
+      assertTrue(lb.isBoundary(p));
+    }
+
+    Coordinate[] allPts = geom.getCoordinates();
+    for (Coordinate p : allPts) {
+      if (! bdySet.contains(p)) {
+        assertFalse(lb.isBoundary(p));
+      }
+    }
+  }
+
+  private Set<Coordinate> extractPoints(String wkt) {
+    Set<Coordinate> ptSet = new HashSet<Coordinate>();
+    if (wkt == null) return ptSet;
+    Coordinate[] pts = read(wkt).getCoordinates();
+    for (Coordinate p : pts) {
+      ptSet.add(p);
+    }
+    return ptSet;
+  }
+
+  private List<LineString> extractLines(Geometry geom) {
+    return LineStringExtracter.getLines(geom);
+  }
+}