tests/qtest: Add a function to check whether a machine is available

It is nowadays possible to build QEMU with a reduced set of machines
in each binary. However, the qtests still hard-code the expected
machines and fail if the binary does not feature the required machine.
Let's get a little bit more flexible here: Add a function that can be
used to query whether a certain machine is available or not, and use
it in some tests as an example (more work has to be done in other
tests which will follow later).

Message-Id: <20211201104347.51922-5-thuth@redhat.com>
Acked-by: John Snow <jsnow@redhat.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>

tests/qtest/boot-serial-test.c

@@ -285,7 +285,8 @@ int main(int argc, char *argv[])
     g_test_init(&argc, &argv, NULL);
 
     for (i = 0; tests[i].arch != NULL; i++) {
-        if (strcmp(arch, tests[i].arch) == 0) {
+        if (g_str_equal(arch, tests[i].arch) &&
+            qtest_has_machine(tests[i].machine)) {
             char *name = g_strdup_printf("boot-serial/%s", tests[i].machine);
             qtest_add_data_func(name, &tests[i], test_machine);
             g_free(name);

tests/qtest/cdrom-test.c

@@ -109,9 +109,11 @@ static void test_cdrom_param(gconstpointer data)
 static void add_cdrom_param_tests(const char **machines)
 {
     while (*machines) {
-        char *testname = g_strdup_printf("cdrom/param/%s", *machines);
-        qtest_add_data_func(testname, *machines, test_cdrom_param);
-        g_free(testname);
+        if (qtest_has_machine(*machines)) {
+            char *testname = g_strdup_printf("cdrom/param/%s", *machines);
+            qtest_add_data_func(testname, *machines, test_cdrom_param);
+            g_free(testname);
+        }
         machines++;
     }
 }

tests/qtest/libqos/libqtest.h

@@ -710,6 +710,14 @@ QDict *qmp_fd(int fd, const char *fmt, ...) GCC_FMT_ATTR(2, 3);
 void qtest_cb_for_every_machine(void (*cb)(const char *machine),
                                 bool skip_old_versioned);
 
+/**
+ * qtest_has_machine:
+ * @machine: The machine to look for
+ *
+ * Returns: true if the machine is available in the target binary.
+ */
+bool qtest_has_machine(const char *machine);
+
 /**
  * qtest_qmp_device_add_qdict:
  * @qts: QTestState instance to operate on

tests/qtest/libqtest.c

@@ -1401,6 +1401,23 @@ void qtest_cb_for_every_machine(void (*cb)(const char *machine),
     }
 }
 
+bool qtest_has_machine(const char *machine)
+{
+    struct MachInfo *machines;
+    int i;
+
+    machines = qtest_get_machines();
+
+    for (i = 0; machines[i].name != NULL; i++) {
+        if (g_str_equal(machine, machines[i].name) ||
+            (machines[i].alias && g_str_equal(machine, machines[i].alias))) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
 /*
  * Generic hot-plugging test via the device_add QMP commands.
  */

tests/qtest/prom-env-test.c

@@ -71,9 +71,11 @@ static void add_tests(const char *machines[])
     char *name;
 
     for (i = 0; machines[i] != NULL; i++) {
-        name = g_strdup_printf("prom-env/%s", machines[i]);
-        qtest_add_data_func(name, machines[i], test_machine);
-        g_free(name);
+        if (qtest_has_machine(machines[i])) {
+            name = g_strdup_printf("prom-env/%s", machines[i]);
+            qtest_add_data_func(name, machines[i], test_machine);
+            g_free(name);
+        }
     }
 }