#415 disjoint sets impl

src/main/java/org/jpeek/graph/Disjoint.java

@@ -23,6 +23,8 @@
  */
 package org.jpeek.graph;
 
+import java.util.ArrayList;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
 import org.cactoos.Scalar;
@@ -48,6 +50,26 @@ public Disjoint(final Graph graph) {
 
     @Override
     public List<Set<Node>> value() throws Exception {
-        throw new UnsupportedOperationException(this.graph.toString());
+        final Set<Node> unvisited = new HashSet<>(this.graph.nodes());
+        final List<Set<Node>> result = new ArrayList<>(unvisited.size());
+        while (!unvisited.isEmpty()) {
+            final Node node = unvisited.iterator().next();
+            final Set<Node> visiting = new HashSet<>();
+            visiting.add(node);
+            final Set<Node> current = new HashSet<>();
+            while (!visiting.isEmpty()) {
+                final Node visit = visiting.iterator().next();
+                current.add(visit);
+                for (final Node connexion:visit.connections()) {
+                    if (!current.contains(connexion)) {
+                        visiting.add(connexion);
+                    }
+                }
+                unvisited.remove(visit);
+                visiting.remove(visit);
+            }
+            result.add(current);
+        }
+        return result;
     }
 }

src/test/java/org/jpeek/graph/DisjointTest.java

@@ -26,7 +26,6 @@
 import java.util.Set;
 import org.cactoos.list.ListOf;
 import org.hamcrest.core.AllOf;
-import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 import org.llorllale.cactoos.matchers.Assertion;
 import org.llorllale.cactoos.matchers.HasValuesMatching;
@@ -38,7 +37,6 @@
 public final class DisjointTest {
 
     @Test
-    @Disabled
     @SuppressWarnings("unchecked")
     public void calculatesDisjointSets() throws Exception {
         final Node one = new Node.Simple("one");
@@ -76,4 +74,36 @@ public void calculatesDisjointSets() throws Exception {
         ).affirm();
     }
 
+    @Test
+    @SuppressWarnings("unchecked")
+    public void calculatesDisjointSetsForUnconnected() throws Exception {
+        final Node one = new Node.Simple("1");
+        final Node two = new Node.Simple("2");
+        final Node three = new Node.Simple("3");
+        final Node four = new Node.Simple("4");
+        final Graph graph = new FakeGraph(
+            new ListOf<>(one, two, three, four)
+        );
+        new Assertion<>(
+            "Must build disjoint sets for unconnected graph",
+            new Disjoint(graph).value(),
+            new AllOf<Iterable<Set<Node>>>(
+                new ListOf<>(
+                    new HasValuesMatching<>(
+                        set -> set.contains(one) && set.size() == 1
+                    ),
+                    new HasValuesMatching<>(
+                        set -> set.contains(two) && set.size() == 1
+                    ),
+                    new HasValuesMatching<>(
+                        set -> set.contains(three) && set.size() == 1
+                    ),
+                    new HasValuesMatching<>(
+                        set -> set.contains(four) && set.size() == 1
+                    )
+                )
+            )
+        ).affirm();
+    }
+
 }

src/test/java/org/jpeek/metrics/Lcom4Test.java

@@ -71,14 +71,9 @@ public final class Lcom4Test {
      *  - methodFive does not use 'num' (this is an orphan method, ignored)
      *  Therefore the number of disjoint sets (LCOM4) should be 1
      *  since all the methods use the same num field.
-     * @todo #310:30min LCOM4: Graph algorithm to determine disjoint sets.
-     *  We started to implement disjoint calculus by putting a disabled test.
-     *  Continue to implement the actual calculus of these sets and remove
-     *  the @Disabled annotation on DisjointTest.
-     *  so we can't trace methodFour that uses 'num' indirectly
-     *  Calculating Disjoint sets (also known as Connected Components),
-     *  requires a graph traversal algorithm like depth-first search.
-     *  This one will be tricky to implement in XSLT.
+     * @todo #415:30min LCOM4: Graph algorithm to determine disjoint sets.
+     *  Disjoint sets calculus is now implemented. We should continue calculating
+     *  LCOM4 metrics (probably you should wait for #413, #403.
      *  After implementing, remove the @Disabled from the below test too.
      */
     @Test