test+ci: add QuadTree/EdgeType tests and harden CI build

Tests:
- gvisual.QuadTreeTest: 6 tests covering Barnes-Hut quadtree build,
  insertion, repulsion forces, and finite-force guarantee for nearby
  bodies (MIN_DIST clamp).
- gvisual.EdgeTypeTest: 16 tests covering enum codes, color/label
  metadata, fromCode lookup (case-insensitive + null/unknown), and
  cluster id derivation.
All 22 new tests pass locally.

CI workflow:
- Exclude *Test.java from production javac (some test files live under
  src/ next to the code they exercise and depend on JUnit, which broke
  the prod compile).
- Add -encoding UTF-8 to all javac invocations (box-drawing chars in
  comments break Windows default encoding).
- Add new test classes to the JUnitCore runner.

Drive-by fixes for pre-existing breakage:
- Main.java: add missing edu.uci.ics.jung.visualization.VisualizationViewer import.
- TimelineMetricsRecorder.java: fix typo'd lowercase 'edge' type
  references to the actual Edge class (8 references).
- ShortestPathFinderTest.java: same typo fix.
- GraphVoronoiPartitioner.java, PerfectGraphAnalyzer.java: add missing
  java.util.stream.Collectors import.
- EulerianPathAnalyzer.java: switch ArrayDeque to LinkedList to match
  the declared map value type.

Author: sauravbhattacharya001

.github/workflows/ci.yml

@@ -10,6 +10,7 @@ jobs:
   build-and-test:
     runs-on: ubuntu-latest
     strategy:
+      fail-fast: false
       matrix:
         java-version: [11, 17]
 
@@ -34,20 +35,32 @@ jobs:
       - name: Compile source
         working-directory: Gvisual
         run: |
+          set -e
           mkdir -p build/classes
-          find src -name '*.java' > sources.txt
-          javac -source 8 -target 8 \
-            -cp "$(find lib -name '*.jar' -not -path 'lib/test/*' | tr '\n' ':')" \
+          # Production sources only: anything under src/ that is NOT a *Test.java
+          # (some test files are checked in under src/ alongside production code).
+          # We still want them on the test classpath later, but they must not
+          # be compiled with javac without junit on the path.
+          find src -name '*.java' ! -name '*Test.java' > sources.txt
+          MAIN_CP="$(find lib -name '*.jar' -not -path 'lib/test/*' | tr '\n' ':')"
+          javac -encoding UTF-8 \
+            -source 8 -target 8 \
+            -cp "$MAIN_CP" \
             -d build/classes \
             @sources.txt
 
       - name: Compile tests
         working-directory: Gvisual
         run: |
+          set -e
           mkdir -p build/test/classes
-          find test -name '*.java' > test-sources.txt
-          javac -source 8 -target 8 \
-            -cp "build/classes:$(find lib -name '*.jar' | tr '\n' ':')" \
+          # All *Test.java files, wherever they live (test/ tree plus a handful
+          # that sit under src/ next to the code they exercise).
+          find src test -name '*Test.java' > test-sources.txt
+          TEST_CP="build/classes:$(find lib -name '*.jar' | tr '\n' ':')"
+          javac -encoding UTF-8 \
+            -source 8 -target 8 \
+            -cp "$TEST_CP" \
             -d build/test/classes \
             @test-sources.txt
 
@@ -58,6 +71,8 @@ jobs:
             org.junit.runner.JUnitCore \
             app.UtilMethodsTest \
             gvisual.EdgeTest \
+            gvisual.EdgeTypeTest \
+            gvisual.QuadTreeTest \
             gvisual.GraphStatsTest \
             gvisual.ShortestPathFinderTest \
             gvisual.GraphMLExporterTest \

Gvisual/src/gvisual/EulerianPathAnalyzer.java

@@ -171,7 +171,7 @@ public EulerianPathResult findEulerianPath() {
         // Build adjacency with Edge tracking
         Map<String, LinkedList<EdgeEntry>> adj = new LinkedHashMap<String, LinkedList<EdgeEntry>>();
         for (String v : graph.getVertices()) {
-            adj.put(v, new ArrayDeque<EdgeEntry>());
+            adj.put(v, new LinkedList<EdgeEntry>());
         }
 
         Set<Edge> allEdges = new HashSet<Edge>();

Gvisual/src/gvisual/GraphVoronoiPartitioner.java

@@ -2,6 +2,7 @@
 
 import edu.uci.ics.jung.graph.Graph;
 import java.util.*;
+import java.util.stream.Collectors;
 
 /**
  * Computes <b>Voronoi-like partitions</b> on a graph: given a set of seed

Gvisual/src/gvisual/Main.java

@@ -6,6 +6,7 @@
 import edu.uci.ics.jung.algorithms.layout.StaticLayout;
 import edu.uci.ics.jung.graph.Graph;
 import edu.uci.ics.jung.graph.UndirectedSparseGraph;
+import edu.uci.ics.jung.visualization.VisualizationViewer;
 import java.awt.BorderLayout;
 import java.awt.Color;
 import java.awt.Dimension;

Gvisual/src/gvisual/PerfectGraphAnalyzer.java

@@ -2,6 +2,7 @@
 
 import edu.uci.ics.jung.graph.Graph;
 import java.util.*;
+import java.util.stream.Collectors;
 
 /**
  * Perfect Graph Analyzer — determines whether a graph is perfect and provides

Gvisual/src/gvisual/TimelineMetricsRecorder.java

@@ -268,17 +268,17 @@ public void setPhaseThreshold(double threshold) {
     /**
      * Records metrics for the current state of the graph at this timeline step.
      */
-    public void recordStep(String label, Graph<String, edge> graph,
-                           List<edge> friendEdges, List<edge> fsEdges,
-                           List<edge> classmateEdges, List<edge> strangerEdges,
-                           List<edge> studyGEdges) {
+    public void recordStep(String label, Graph<String, Edge> graph,
+                           List<Edge> friendEdges, List<Edge> fsEdges,
+                           List<Edge> classmateEdges, List<Edge> strangerEdges,
+                           List<Edge> studyGEdges) {
         if (graph == null) {
             throw new IllegalArgumentException("Graph must not be null");
         }
 
         Set<String> currentNodes = new HashSet<>(graph.getVertices());
         Set<String> currentEdgeKeys = new HashSet<>();
-        for (edge e : graph.getEdges()) {
+        for (Edge e : graph.getEdges()) {
             currentEdgeKeys.add(edgeKey(e));
         }
 
@@ -304,7 +304,7 @@ public void recordStep(String label, Graph<String, edge> graph,
         }
 
         double totalWeight = 0;
-        for (edge e : graph.getEdges()) {
+        for (Edge e : graph.getEdges()) {
             totalWeight += e.getWeight();
         }
         double avgWt = edgeCount > 0 ? totalWeight / edgeCount : 0;
@@ -475,22 +475,22 @@ private static double computeDensity(int nodes, int edges) {
         return (2.0 * edges) / (nodes * (nodes - 1));
     }
 
-    private static String edgeKey(edge e) {
+    private static String edgeKey(Edge e) {
         String v1 = e.getVertex1();
         String v2 = e.getVertex2();
         if (v1.compareTo(v2) > 0) { String tmp = v1; v1 = v2; v2 = tmp; }
         return v1 + "|" + v2 + "|" + e.getType();
     }
 
-    private static int countInGraph(Graph<String, edge> graph, List<edge> edges) {
+    private static int countInGraph(Graph<String, Edge> graph, List<Edge> edges) {
         int count = 0;
-        for (edge e : edges) {
+        for (Edge e : edges) {
             if (graph.containsEdge(e)) count++;
         }
         return count;
     }
 
-    private static int countComponents(Graph<String, edge> graph) {
+    private static int countComponents(Graph<String, Edge> graph) {
         Set<String> visited = new HashSet<>();
         int components = 0;
         for (String v : graph.getVertices()) {

Gvisual/src/test/gvisual/ShortestPathFinderTest.java

@@ -17,18 +17,18 @@ public class ShortestPathFinderTest {
 
     // ── Helpers ─────────────────────────────────────────────────────
 
-    private static edge addEdge(Graph<String, edge> g, String v1, String v2) {
+    private static Edge addEdge(Graph<String, Edge> g, String v1, String v2) {
         g.addVertex(v1);
         g.addVertex(v2);
-        edge e = new edge("f", v1, v2);
+        Edge e = new Edge("f", v1, v2);
         g.addEdge(e, v1, v2);
         return e;
     }
 
-    private static edge addWeightedEdge(Graph<String, edge> g, String v1, String v2, float w) {
+    private static Edge addWeightedEdge(Graph<String, Edge> g, String v1, String v2, float w) {
         g.addVertex(v1);
         g.addVertex(v2);
-        edge e = new edge("f", v1, v2);
+        Edge e = new Edge("f", v1, v2);
         e.setWeight(w);
         g.addEdge(e, v1, v2);
         return e;
@@ -45,7 +45,7 @@ public void constructor_nullGraph_throws() {
 
     @Test
     public void byHops_sameVertex_returnsZeroHopPath() {
-        Graph<String, edge> g = new UndirectedSparseGraph<>();
+        Graph<String, Edge> g = new UndirectedSparseGraph<>();
         g.addVertex("A");
         ShortestPathFinder spf = new ShortestPathFinder(g);
 
@@ -59,7 +59,7 @@ public void byHops_sameVertex_returnsZeroHopPath() {
 
     @Test
     public void byHops_directNeighbor_returns1Hop() {
-        Graph<String, edge> g = new UndirectedSparseGraph<>();
+        Graph<String, Edge> g = new UndirectedSparseGraph<>();
         addEdge(g, "A", "B");
         ShortestPathFinder spf = new ShortestPathFinder(g);
 
@@ -73,7 +73,7 @@ public void byHops_directNeighbor_returns1Hop() {
     public void byHops_choosesFewestHops_notLowestWeight() {
         // A --1-- B --1-- C (2 hops)
         // A --10-- C              (1 hop, heavier)
-        Graph<String, edge> g = new UndirectedSparseGraph<>();
+        Graph<String, Edge> g = new UndirectedSparseGraph<>();
         addWeightedEdge(g, "A", "B", 1f);
         addWeightedEdge(g, "B", "C", 1f);
         addWeightedEdge(g, "A", "C", 10f);
@@ -87,7 +87,7 @@ public void byHops_choosesFewestHops_notLowestWeight() {
 
     @Test
     public void byHops_disconnectedVertices_returnsNull() {
-        Graph<String, edge> g = new UndirectedSparseGraph<>();
+        Graph<String, Edge> g = new UndirectedSparseGraph<>();
         g.addVertex("A");
         g.addVertex("B");
         ShortestPathFinder spf = new ShortestPathFinder(g);
@@ -97,7 +97,7 @@ public void byHops_disconnectedVertices_returnsNull() {
 
     @Test
     public void byHops_linearChain_returnsCorrectPath() {
-        Graph<String, edge> g = new UndirectedSparseGraph<>();
+        Graph<String, Edge> g = new UndirectedSparseGraph<>();
         addEdge(g, "A", "B");
         addEdge(g, "B", "C");
         addEdge(g, "C", "D");
@@ -112,14 +112,14 @@ public void byHops_linearChain_returnsCorrectPath() {
 
     @Test(expected = IllegalArgumentException.class)
     public void byHops_nullSource_throws() {
-        Graph<String, edge> g = new UndirectedSparseGraph<>();
+        Graph<String, Edge> g = new UndirectedSparseGraph<>();
         g.addVertex("A");
         new ShortestPathFinder(g).findShortestByHops(null, "A");
     }
 
     @Test(expected = IllegalArgumentException.class)
     public void byHops_vertexNotInGraph_throws() {
-        Graph<String, edge> g = new UndirectedSparseGraph<>();
+        Graph<String, Edge> g = new UndirectedSparseGraph<>();
         g.addVertex("A");
         new ShortestPathFinder(g).findShortestByHops("A", "Z");
     }
@@ -128,7 +128,7 @@ public void byHops_vertexNotInGraph_throws() {
 
     @Test
     public void byWeight_sameVertex_returnsZeroWeight() {
-        Graph<String, edge> g = new UndirectedSparseGraph<>();
+        Graph<String, Edge> g = new UndirectedSparseGraph<>();
         g.addVertex("X");
         ShortestPathFinder spf = new ShortestPathFinder(g);
 
@@ -142,7 +142,7 @@ public void byWeight_sameVertex_returnsZeroWeight() {
     public void byWeight_prefersLighterPath() {
         // A --1-- B --1-- C (weight 2, 2 hops)
         // A --10-- C          (weight 10, 1 hop)
-        Graph<String, edge> g = new UndirectedSparseGraph<>();
+        Graph<String, Edge> g = new UndirectedSparseGraph<>();
         addWeightedEdge(g, "A", "B", 1f);
         addWeightedEdge(g, "B", "C", 1f);
         addWeightedEdge(g, "A", "C", 10f);
@@ -157,7 +157,7 @@ public void byWeight_prefersLighterPath() {
     @Test
     public void byWeight_zeroWeightEdges_treatedAsWeight1() {
         // Zero-weight edges should be normalized to 1.0
-        Graph<String, edge> g = new UndirectedSparseGraph<>();
+        Graph<String, Edge> g = new UndirectedSparseGraph<>();
         addEdge(g, "A", "B"); // weight 0 (default) -> treated as 1.0
         addEdge(g, "B", "C"); // weight 0 -> treated as 1.0
         ShortestPathFinder spf = new ShortestPathFinder(g);
@@ -169,7 +169,7 @@ public void byWeight_zeroWeightEdges_treatedAsWeight1() {
 
     @Test
     public void byWeight_disconnected_returnsNull() {
-        Graph<String, edge> g = new UndirectedSparseGraph<>();
+        Graph<String, Edge> g = new UndirectedSparseGraph<>();
         g.addVertex("A");
         g.addVertex("B");
         ShortestPathFinder spf = new ShortestPathFinder(g);
@@ -179,7 +179,7 @@ public void byWeight_disconnected_returnsNull() {
 
     @Test(expected = IllegalArgumentException.class)
     public void byWeight_negativeEdge_throws() {
-        Graph<String, edge> g = new UndirectedSparseGraph<>();
+        Graph<String, Edge> g = new UndirectedSparseGraph<>();
         addWeightedEdge(g, "A", "B", -5f);
         new ShortestPathFinder(g).findShortestByWeight("A", "B");
     }
@@ -188,7 +188,7 @@ public void byWeight_negativeEdge_throws() {
 
     @Test
     public void reachable_isolatedVertex_returnsSelf() {
-        Graph<String, edge> g = new UndirectedSparseGraph<>();
+        Graph<String, Edge> g = new UndirectedSparseGraph<>();
         g.addVertex("A");
         ShortestPathFinder spf = new ShortestPathFinder(g);
 
@@ -198,7 +198,7 @@ public void reachable_isolatedVertex_returnsSelf() {
 
     @Test
     public void reachable_connectedComponent_returnsAll() {
-        Graph<String, edge> g = new UndirectedSparseGraph<>();
+        Graph<String, Edge> g = new UndirectedSparseGraph<>();
         addEdge(g, "A", "B");
         addEdge(g, "B", "C");
         g.addVertex("D"); // isolated
@@ -213,29 +213,29 @@ public void reachable_connectedComponent_returnsAll() {
 
     @Test
     public void areConnected_sameVertex_returnsTrue() {
-        Graph<String, edge> g = new UndirectedSparseGraph<>();
+        Graph<String, Edge> g = new UndirectedSparseGraph<>();
         g.addVertex("A");
         assertTrue(new ShortestPathFinder(g).areConnected("A", "A"));
     }
 
     @Test
     public void areConnected_directNeighbors_returnsTrue() {
-        Graph<String, edge> g = new UndirectedSparseGraph<>();
+        Graph<String, Edge> g = new UndirectedSparseGraph<>();
         addEdge(g, "A", "B");
         assertTrue(new ShortestPathFinder(g).areConnected("A", "B"));
     }
 
     @Test
     public void areConnected_disconnected_returnsFalse() {
-        Graph<String, edge> g = new UndirectedSparseGraph<>();
+        Graph<String, Edge> g = new UndirectedSparseGraph<>();
         g.addVertex("A");
         g.addVertex("B");
         assertFalse(new ShortestPathFinder(g).areConnected("A", "B"));
     }
 
     @Test
     public void areConnected_transitivelyConnected_returnsTrue() {
-        Graph<String, edge> g = new UndirectedSparseGraph<>();
+        Graph<String, Edge> g = new UndirectedSparseGraph<>();
         addEdge(g, "A", "B");
         addEdge(g, "B", "C");
         addEdge(g, "C", "D");
@@ -246,7 +246,7 @@ public void areConnected_transitivelyConnected_returnsTrue() {
 
     @Test
     public void pathResult_toString_formatsCorrectly() {
-        Graph<String, edge> g = new UndirectedSparseGraph<>();
+        Graph<String, Edge> g = new UndirectedSparseGraph<>();
         addWeightedEdge(g, "A", "B", 3f);
         addWeightedEdge(g, "B", "C", 4f);
         ShortestPathFinder spf = new ShortestPathFinder(g);
@@ -264,7 +264,7 @@ public void pathResult_toString_formatsCorrectly() {
 
     @Test
     public void byHops_directedGraph_respectsEdgeDirection() {
-        Graph<String, edge> g = new DirectedSparseGraph<>();
+        Graph<String, Edge> g = new DirectedSparseGraph<>();
         addEdge(g, "A", "B"); // A -> B only
         addEdge(g, "B", "C"); // B -> C only
         ShortestPathFinder spf = new ShortestPathFinder(g);
@@ -292,7 +292,7 @@ public void byWeight_diamondGraph_findsOptimalPath() {
         //   2   1
         //    \ /
         //     C
-        Graph<String, edge> g = new UndirectedSparseGraph<>();
+        Graph<String, Edge> g = new UndirectedSparseGraph<>();
         addWeightedEdge(g, "A", "B", 1f);
         addWeightedEdge(g, "A", "C", 2f);
         addWeightedEdge(g, "B", "D", 5f);