DAOS-14594 test: fix dfs_parallel xml generation (#13312)

Since cmocka is not MPI-aware, force all ranks other than rank 0 to write to stdout to avoid race conditions with the XML file.

Signed-off-by: Dalton Bohning <[email protected]>

src/tests/suite/dfs_test.c

@@ -1,5 +1,5 @@
 /**
- * (C) Copyright 2019-2022 Intel Corporation.
+ * (C) Copyright 2019-2024 Intel Corporation.
  *
  * SPDX-License-Identifier: BSD-2-Clause-Patent
  */
@@ -81,16 +81,17 @@ run_specified_tests(const char *tests, int rank, int size,
 int
 main(int argc, char **argv)
 {
-	test_arg_t	*arg;
-	char		 tests[64];
-	char		*exclude_str = NULL;
-	int		 ntests = 0;
-	int		 nr_failed = 0;
-	int		 nr_total_failed = 0;
-	int		 opt = 0, index = 0;
-	int		 rank;
-	int		 size;
-	int		 rc;
+	test_arg_t *arg;
+	char        tests[64];
+	char       *exclude_str           = NULL;
+	char       *cmocka_message_output = NULL;
+	int         ntests                = 0;
+	int         nr_failed             = 0;
+	int         nr_total_failed       = 0;
+	int         opt = 0, index = 0;
+	int         rank;
+	int         size;
+	int         rc;
 
 	d_register_alt_assert(mock_assert);
 
@@ -166,6 +167,16 @@ main(int argc, char **argv)
 		tests[new_idx] = '\0';
 	}
 
+	/** if writing XML, force all ranks other than rank 0 to use stdout to avoid conflicts */
+	cmocka_message_output = getenv("CMOCKA_MESSAGE_OUTPUT");
+	if (rank != 0 && cmocka_message_output && strcasecmp(cmocka_message_output, "xml") == 0) {
+		rc = d_setenv("CMOCKA_MESSAGE_OUTPUT", "stdout", 1);
+		if (rc) {
+			print_message("d_setenv() failed with %d\n", rc);
+			return -1;
+		}
+	}
+
 	nr_failed = run_specified_tests(tests, rank, size, NULL, 0);
 
 exit: