tests/qtest: Introduce qtest_init_with_env_and_capabilities()

This patch adds a new version of qtest_init_with_env() that allows
specifying QMP capabilities that should be enabled during handshake.
This is useful for example if a test needs out-of-band execution of QMP
commands, it can initialize with the oob capability.

Signed-off-by: Juraj Marcin <jmarcin@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: Fabiano Rosas <farosas@suse.de>

tests/qtest/libqtest.c

@@ -543,7 +543,9 @@ QTestState *qtest_init_without_qmp_handshake(const char *extra_args)
     return qtest_init_internal(qtest_qemu_binary(NULL), extra_args);
 }
 
-QTestState *qtest_init_with_env(const char *var, const char *extra_args)
+QTestState *qtest_init_with_env_and_capabilities(const char *var,
+                                                 const char *extra_args,
+                                                 QList *capabilities)
 {
     QTestState *s = qtest_init_internal(qtest_qemu_binary(var), extra_args);
     QDict *greeting;
@@ -551,11 +553,23 @@ QTestState *qtest_init_with_env(const char *var, const char *extra_args)
     /* Read the QMP greeting and then do the handshake */
     greeting = qtest_qmp_receive(s);
     qobject_unref(greeting);
-    qobject_unref(qtest_qmp(s, "{ 'execute': 'qmp_capabilities' }"));
+    if (capabilities) {
+        qtest_qmp_assert_success(s,
+                                 "{ 'execute': 'qmp_capabilities', "
+                                 "'arguments': { 'enable': %p } }",
+                                 qobject_ref(capabilities));
+    } else {
+        qtest_qmp_assert_success(s, "{ 'execute': 'qmp_capabilities' }");
+    }
 
     return s;
 }
 
+QTestState *qtest_init_with_env(const char *var, const char *extra_args)
+{
+    return qtest_init_with_env_and_capabilities(var, extra_args, NULL);
+}
+
 QTestState *qtest_init(const char *extra_args)
 {
     return qtest_init_with_env(NULL, extra_args);

tests/qtest/libqtest.h

@@ -19,6 +19,7 @@
 
 #include "qapi/qmp/qobject.h"
 #include "qapi/qmp/qdict.h"
+#include "qapi/qmp/qlist.h"
 #include "libqmp.h"
 
 typedef struct QTestState QTestState;
@@ -68,6 +69,22 @@ QTestState *qtest_init(const char *extra_args);
  */
 QTestState *qtest_init_with_env(const char *var, const char *extra_args);
 
+/**
+ * qtest_init_with_env_and_capabilities:
+ * @var: Environment variable from where to take the QEMU binary
+ * @extra_args: Other arguments to pass to QEMU.  CAUTION: these
+ * arguments are subject to word splitting and shell evaluation.
+ * @capabilities: list of QMP capabilities (strings) to enable
+ *
+ * Like qtest_init_with_env(), but enable specified capabilities during
+ * hadshake.
+ *
+ * Returns: #QTestState instance.
+ */
+QTestState *qtest_init_with_env_and_capabilities(const char *var,
+                                                 const char *extra_args,
+                                                 QList *capabilities);
+
 /**
  * qtest_init_without_qmp_handshake:
  * @extra_args: other arguments to pass to QEMU.  CAUTION: these