tests: avoid re-execing test once for each mock

When debugging tests under GDB/valgrind there is a significant
delay each time an execve is done as they scan shared libraries
once again. For tests which use many mock libraries, we have
been invoking execve many times which makes the debug experience
horrible. This changes our framework to activate the full
set of mock libraries in one single execve.
Reviewed-by: NMichal Privoznik <mprivozn@redhat.com>
Signed-off-by: NDaniel P. Berrangé <berrange@redhat.com>

tests/qemucapsprobe.c

@@ -46,8 +46,14 @@ main(int argc, char **argv)
 {
     virThread thread;
     virQEMUCapsPtr caps;
+    const char *mock = VIR_TEST_MOCK("qemucapsprobe");
 
-    VIR_TEST_PRELOAD(VIR_TEST_MOCK("qemucapsprobe"));
+    if (!virFileIsExecutable(mock)) {
+        perror(mock);
+        return EXIT_FAILURE;
+    }
+
+    VIR_TEST_PRELOAD(mock);
 
     if (argc != 2) {
         fprintf(stderr, "%s QEMU_binary\n", argv[0]);

tests/testutils.c

@@ -856,15 +856,34 @@ int virTestMain(int argc,
     virLogOutputPtr *outputs = NULL;
     g_autofree char *baseprogname = NULL;
     const char *progname;
-
-    if (getenv("VIR_TEST_FILE_ACCESS"))
-        VIR_TEST_PRELOAD(VIR_TEST_MOCK("virtest"));
+    g_autofree const char **preloads = NULL;
+    size_t npreloads = 0;
+    g_autofree char *mock = NULL;
+
+    if (getenv("VIR_TEST_FILE_ACCESS")) {
+        preloads = g_renew(const char *, preloads, npreloads + 2);
+        preloads[npreloads++] = VIR_TEST_MOCK("virtest");
+        preloads[npreloads] = NULL;
+    }
 
     va_start(ap, func);
-    while ((lib = va_arg(ap, const char *)))
-        VIR_TEST_PRELOAD(lib);
+    while ((lib = va_arg(ap, const char *))) {
+        if (!virFileIsExecutable(lib)) {
+            perror(lib);
+            return EXIT_FAILURE;
+        }
+
+        preloads = g_renew(const char *, preloads, npreloads + 2);
+        preloads[npreloads++] = lib;
+        preloads[npreloads] = NULL;
+    }
     va_end(ap);
 
+    if (preloads) {
+        mock = g_strjoinv(":", (char **)preloads);
+        VIR_TEST_PRELOAD(mock);
+    }
+
     progname = baseprogname = g_path_get_basename(argv[0]);
     if (STRPREFIX(progname, "lt-"))
         progname += 3;

tests/testutils.h

@@ -127,19 +127,15 @@ int virTestMain(int argc,
 # define MOCK_EXT ".so"
 #endif
 
-#define VIR_TEST_PRELOAD(lib) \
+#define VIR_TEST_PRELOAD(libs) \
     do { \
         const char *preload = getenv(PRELOAD_VAR); \
-        if (preload == NULL || strstr(preload, lib) == NULL) { \
+        if (preload == NULL || strstr(preload, libs) == NULL) { \
             char *newenv; \
-            if (!virFileIsExecutable(lib)) { \
-                perror(lib); \
-                return EXIT_FAILURE; \
-            } \
             if (!preload) { \
-                newenv = (char *) lib; \
+                newenv = (char *) libs; \
             } else { \
-                newenv = g_strdup_printf("%s:%s", lib, preload); \
+                newenv = g_strdup_printf("%s:%s", libs, preload); \
             } \
             g_setenv(PRELOAD_VAR, newenv, TRUE); \
             FORCE_FLAT_NAMESPACE \