WIP: Basic tests sending a buffer of chars

testing/adios2/engine/bp/CMakeLists.txt

@@ -255,6 +255,10 @@ bp5agg_gtest_add_tests(ReadMultithreaded MPI_NONE)
 bp5agg_gtest_add_tests(NewFileAppendMode MPI_NONE)
 bp5agg_gtest_add_tests(StepsFileGlobalArray MPI_ALLOW)
 
+if(ADIOS2_HAVE_MPI)
+  gtest_add_tests_helper(CharBufferMPI MPI_ONLY BP Send.Receive CharBuf)
+endif()
+
 # Only a single test is enough, pick the latest engine
 gtest_add_tests_helper(AccuracyDefaults MPI_NONE BP Engine.BP. .BP5
   WORKING_DIRECTORY ${BP5_DIR} EXTRA_ARGS "BP5"

testing/adios2/engine/bp/TestBPCharBufferMPI.cpp

@@ -0,0 +1,89 @@
+/*
+ * Distributed under the OSI-approved Apache License, Version 2.0.  See
+ * accompanying file Copyright.txt for details.
+ */
+
+#include <adios2.h>
+#include <adios2/helper/adiosCommMPI.h>
+#include <gtest/gtest.h>
+#include <mpi.h>
+
+using namespace adios2;
+
+namespace
+{
+int worldRank, worldSize;
+}
+
+class CharBufferMPITest : public ::testing::Test
+{
+public:
+    CharBufferMPITest() = default;
+};
+
+TEST_F(CharBufferMPITest, TestSendReceiveCharBuffer)
+{
+    helper::Comm comm = adios2::helper::CommWithMPI(MPI_COMM_WORLD);
+
+    int sendToRank = worldRank >= worldSize - 1 ? 0 : worldRank + 1;
+    int recvFromRank = worldRank <= 0 ? worldSize - 1 : worldRank - 1;
+
+    std::vector<char> sendBuffer = {1, 2, 3};
+
+    comm.Isend(sendBuffer.data(), sendBuffer.size(), sendToRank, 0);
+
+    std::vector<char> recvBuffer;
+    recvBuffer.resize(sendBuffer.size());
+
+    comm.Recv(recvBuffer.data(), recvBuffer.size(), recvFromRank, 0);
+
+    ASSERT_EQ(recvBuffer.size(), sendBuffer.size());
+
+    for (size_t i = 0; i < recvBuffer.size(); ++i)
+    {
+        ASSERT_EQ(recvBuffer[i], sendBuffer[i]);
+    }
+}
+
+TEST_F(CharBufferMPITest, TestSendReceiveCharBufferNoHelper)
+{
+    int sendToRank = worldRank >= worldSize - 1 ? 0 : worldRank + 1;
+    int recvFromRank = worldRank <= 0 ? worldSize - 1 : worldRank - 1;
+    constexpr int count = 3;
+
+    // Send the buffer of chars (non-blocking)
+    MPI_Request request = MPI_REQUEST_NULL;
+    char sendBuffer[count] = {1, 2, 3};
+    MPI_Isend(&sendBuffer, count, MPI_CHAR, sendToRank, 0, MPI_COMM_WORLD, &request);
+
+    // Receive the buffer of chars (blocking)
+    MPI_Status status;
+    char recvBuffer[count];
+    int ret = MPI_Recv(&recvBuffer, count, MPI_CHAR, recvFromRank, 0, MPI_COMM_WORLD, &status);
+
+    ASSERT_EQ(ret, MPI_SUCCESS);
+
+    int mpiCount = 0;
+    ret = MPI_Get_count(&status, MPI_CHAR, &mpiCount);
+
+    ASSERT_EQ(ret, MPI_SUCCESS);
+    ASSERT_EQ(mpiCount, count);
+
+    for (int i = 0; i < count; ++i)
+    {
+        ASSERT_EQ(recvBuffer[i], sendBuffer[i]);
+    }
+}
+
+int main(int argc, char **argv)
+{
+    MPI_Init(&argc, &argv);
+    MPI_Comm_rank(MPI_COMM_WORLD, &worldRank);
+    MPI_Comm_size(MPI_COMM_WORLD, &worldSize);
+    ::testing::InitGoogleTest(&argc, argv);
+
+    int result = RUN_ALL_TESTS();
+
+    MPI_Finalize();
+    return result;
+}