test: Add unit test verifying c application can dlopen library

This test checks whether plugin library can be loaded with dlopen from
c application . The reason is that plugin formerly didn't link against
libstdc++ and relied on application to provide required linkage. This
has been fixed by recent commit but test was not added.

Signed-off-by: Michael Axtmann <[email protected]>

Author: maxtmann

tests/unit/.gitignore

@@ -8,3 +8,4 @@ region_based_tuner
 scheduler
 histogram
 histogram_binner
+dlopen_c_test

tests/unit/Makefile.am

@@ -13,6 +13,10 @@ AM_CPPFLAGS += -isystem $(abs_top_srcdir)/3rd-party/uthash/include
 LDADD = $(top_builddir)/src/libinternal_net_plugin.la
 noinst_HEADERS = test-common.h
 
+# Define C compiler for dlopen_c_test
+dlopen_c_test_CFLAGS = $(AM_CFLAGS)
+dlopen_c_test_LDADD = -ldl
+
 noinst_PROGRAMS = \
 	freelist \
 	msgbuff \
@@ -21,7 +25,8 @@ noinst_PROGRAMS = \
 	ep_addr_list \
 	mr \
 	histogram_binner \
-	histogram
+	histogram \
+	dlopen_c_test
 
 if WANT_PLATFORM_AWS
 noinst_PROGRAMS += aws_platform_mapper
@@ -47,6 +52,7 @@ mr_SOURCES = mr.cpp
 aws_platform_mapper_SOURCES = aws_platform_mapper.cpp
 histogram_binner_SOURCES = histogram_binner.cpp
 histogram_SOURCES = histogram.cpp
+dlopen_c_test_SOURCES = dlopen_c_test.c
 
 TESTS = $(noinst_PROGRAMS)
 endif

tests/unit/dlopen_c_test.c

@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2025 Amazon.com, Inc. or its affiliates. All rights reserved.
+ */
+
+#include "config.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <assert.h>
+#include <stdint.h>
+#include <dlfcn.h>
+#include <string.h>
+
+#include "test-logger.h"
+
+nccl_ofi_logger_t ofi_log_function = NULL;
+
+/*
+ * This is a simple C test that loads the shared object dynamically
+ * for the AWS OFI NCCL plugin
+ */
+
+int main(int argc, char *argv[])
+{
+    void *handle = NULL;
+    char *error = NULL;
+    int ret = 0;
+
+    /* Set up logging */
+    ofi_log_function = logger;
+
+    /* Try to load the appropriate shared object based on build configuration */
+#ifdef HAVE_NEURON
+    const char *lib_path = "../../src/.libs/libnccom-net.so";
+    NCCL_OFI_INFO(NCCL_INIT, "Testing Neuron build: attempting to load %s\n", lib_path);
+#else
+    const char *lib_path = "../../src/.libs/libnccl_net_ofi.so";
+    NCCL_OFI_INFO(NCCL_INIT, "Testing standard build: attempting to load %s\n", lib_path);
+#endif
+
+    /* Open the shared object file */
+    handle = dlopen(lib_path, RTLD_LAZY);
+    if (!handle) {
+        NCCL_OFI_WARN("Error opening shared object: %s\n", dlerror());
+        return 1;
+    }
+
+    /* Log test progress */
+    NCCL_OFI_INFO(NCCL_INIT, "Successfully loaded AWS OFI NCCL plugin shared object");
+
+    /* Perform some basic assertions to verify test framework */
+    assert(handle != NULL);
+
+    /* Close the shared object */
+    dlclose(handle);
+
+    NCCL_OFI_INFO(NCCL_INIT, "Test completed successfully!\n");
+
+    return 0;
+}

tests/unit/test-common.h

@@ -9,41 +9,6 @@
 #include <stdio.h>
 
 #include "nccl_ofi.h"
-#include "nccl_ofi_log.h"
-
-static inline void logger(ncclDebugLogLevel level, unsigned long flags, const char *filefunc,
-			  int line, const char *fmt, ...)
-{
-	va_list vargs;
-
-	switch (level) {
-		case NCCL_LOG_WARN:
-			printf("WARN: Function: %s Line: %d: ", filefunc, line);
-			break;
-		case NCCL_LOG_INFO:
-			printf("INFO: Function: %s Line: %d: ", filefunc, line);
-			break;
-		case NCCL_LOG_TRACE:
-#if OFI_NCCL_TRACE
-			printf("TRACE: Function: %s Line: %d: ", filefunc, line);
-			break;
-#else
-			return;
-#endif
-		case NCCL_LOG_NONE:
-		case NCCL_LOG_VERSION:
-		case NCCL_LOG_ABORT:
-		default:
-			break;
-	};
-
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Wformat=2"
-	va_start(vargs, fmt);
-	vprintf(fmt, vargs);
-	printf("\n");
-	va_end(vargs);
-#pragma GCC diagnostic pop
-}
+#include "test-logger.h"
 
 #endif // End TEST_COMMON_H_

tests/unit/test-logger.h

@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2018-2023 Amazon.com, Inc. or its affiliates. All rights reserved.
+ */
+
+#ifndef TEST_LOGGER_H_
+#define TEST_LOGGER_H_
+
+#include <stdarg.h>
+#include <stdio.h>
+
+#include "nccl_ofi_log.h"
+
+static inline void logger(ncclDebugLogLevel level, unsigned long flags, const char *filefunc,
+			  int line, const char *fmt, ...)
+{
+	va_list vargs;
+
+	switch (level) {
+		case NCCL_LOG_WARN:
+			printf("WARN: Function: %s Line: %d: ", filefunc, line);
+			break;
+		case NCCL_LOG_INFO:
+			printf("INFO: Function: %s Line: %d: ", filefunc, line);
+			break;
+		case NCCL_LOG_TRACE:
+#if OFI_NCCL_TRACE
+			printf("TRACE: Function: %s Line: %d: ", filefunc, line);
+			break;
+#else
+			return;
+#endif
+		case NCCL_LOG_NONE:
+		case NCCL_LOG_VERSION:
+		case NCCL_LOG_ABORT:
+		default:
+			break;
+	};
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wformat=2"
+	va_start(vargs, fmt);
+	vprintf(fmt, vargs);
+	printf("\n");
+	va_end(vargs);
+#pragma GCC diagnostic pop
+}
+#endif // End TEST_LOGGER_H_
+