Add CPP test writing empty graph to disk, and reading successfully.

Author: c-bebop

networkit/cpp/io/test/IOGTest.cpp

@@ -11,6 +11,7 @@
 #include <cassert>
 #include <chrono>
 #include <cstring>
+#include <filesystem>
 #include <fstream>
 #include <iostream>
 #include <limits>
@@ -646,6 +647,17 @@ TEST_F(IOGTest, testGraphToolBinaryReader) {
     EXPECT_FALSE(G.isDirected());
 }
 
+TEST_F(IOGTest, testGraphToolBinaryEmptyFileCanBeRead) {
+    Graph graph(0, false, true);
+    GraphToolBinaryWriter writer;
+    std::filesystem::path const path = "output/empty_graph.gt";
+    writer.write(graph, path.c_str());
+
+    GraphToolBinaryReader reader;
+    Graph graph_read = reader.read(path.c_str());
+    EXPECT_EQ(graph.numberOfNodes(), graph_read.numberOfNodes());
+}
+
 TEST_F(IOGTest, testGraphToolBinaryWriter) {
     Graph G(10, false, false);
     G.addEdge(0, 1);