From 2024f496eb5010276257e5e6f7234be5a477a90c Mon Sep 17 00:00:00 2001
From: Siddhartha <siddharthaiist@gmail.com>
Date: Sat, 16 Oct 2021 11:13:21 +0530
Subject: [PATCH] basic tests for union-find data structure

---
 .gitignore             |  3 +++
 CMakeLists.txt         |  1 +
 test/UnionFindTest.cpp | 54 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 58 insertions(+)
 create mode 100644 test/UnionFindTest.cpp

diff --git a/.gitignore b/.gitignore
index 259148fa1..59ebb2404 100644
--- a/.gitignore
+++ b/.gitignore
@@ -30,3 +30,6 @@
 *.exe
 *.out
 *.app
+
+# ignore the build folder contents from git
+build/
\ No newline at end of file
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 45e1346dd..4ead0d845 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -60,6 +60,7 @@ add_executable(test_exe test/main.cpp
 						test/PartitionTest.cpp
 						test/DialTest.cpp
 						test/GraphSlicingTest.cpp
+						test/UnionFindTest.cpp
 				)
 target_include_directories(test_exe PUBLIC
 						  "${PROJECT_SOURCE_DIR}/include"
diff --git a/test/UnionFindTest.cpp b/test/UnionFindTest.cpp
new file mode 100644
index 000000000..3487fce4f
--- /dev/null
+++ b/test/UnionFindTest.cpp
@@ -0,0 +1,54 @@
+#include "gtest/gtest.h"
+#include "CXXGraph.hpp"
+
+TEST(UnionFindTest, test_1)
+{
+    CXXGRAPH::Node<int> node0(0, 0);
+    CXXGRAPH::Node<int> node1(1, 1);
+    CXXGRAPH::Node<int> node2(2, 2);
+    CXXGRAPH::Node<int> node3(3, 3);
+
+    /*
+            0
+           1 2
+          3
+    */
+    CXXGRAPH::UndirectedWeightedEdge<int> edge1(0, node0, node1, 5);
+    CXXGRAPH::UndirectedWeightedEdge<int> edge2(1, node0, node2, 10);
+    CXXGRAPH::UndirectedWeightedEdge<int> edge3(2, node1, node3, 5);
+
+    std::list<const CXXGRAPH::Edge<int> *> edgeSet;
+    edgeSet.push_back(&edge1);
+
+    CXXGRAPH::Graph<int> graph(edgeSet);
+
+    // every element is a subset of itself
+    CXXGRAPH::Subset subset[4] = {{0, 0}, {1, 0}, {2, 0}, {3, 0}};
+    auto res = graph.setFind(subset, node0.getId());
+    ASSERT_EQ(res, 0);
+    res = graph.setFind(subset, node1.getId());
+    ASSERT_EQ(res, 1);
+    res = graph.setFind(subset, node2.getId());
+    ASSERT_EQ(res, 2);
+
+    // element 1 & 2 are subset of 0
+    // element 3 is subset of 1
+    CXXGRAPH::Subset subset1[4] = {{0, 0}, {0, 0}, {0, 0}, {1, 0}};
+    auto res1 = graph.setFind(subset1, node0.getId());
+    ASSERT_EQ(res1, 0);
+    res = graph.setFind(subset1, node3.getId());
+    ASSERT_EQ(res1, 0);
+    res = graph.setFind(subset1, node2.getId());
+    ASSERT_EQ(res1, 0);
+
+    // union of (node 1 & node3)  should increase node0 rank by 1
+    CXXGRAPH::Subset subset2[4] = {{0, 0}, {0, 0}, {0, 0}, {1, 0}};
+    graph.setUnion(subset2, node1.getId(), node3.getId());
+    ASSERT_EQ(subset2[0].rank, 1);
+    ASSERT_EQ(subset2[3].parent, 0);
+
+    // rank shouldn't increase since both have the same parent
+    graph.setUnion(subset2, node2.getId(), node3.getId());
+    ASSERT_EQ(subset2[0].rank, 1);
+    ASSERT_EQ(subset2[3].parent, 0);
+}
\ No newline at end of file