qapi: Simplify error cleanup in test-qmp-*

We have several tests that perform multiple sub-actions that are
expected to fail.  Asserting that an error occurred, then clearing
it up to prepare for the next action, turned into enough
boilerplate that it was sometimes forgotten (for example, a number
of tests added to test-qmp-input-visitor.c in d88f5fd leaked err).
Worse, if an error is not reset to NULL, we risk invalidating
later use of that error (passing a non-NULL err into a function
is generally a bad idea).  Encapsulate the boilerplate into a
single helper function error_free_or_abort(), and consistently
use it.

The new function is added into error.c for use everywhere,
although it is anticipated that testsuites will be the main
client.

Signed-off-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>

include/qapi/error.h

@@ -30,6 +30,10 @@
  * Handle an error without reporting it (just for completeness):
  *     error_free(err);
  *
+ * Assert that an expected error occurred, but clean it up without
+ * reporting it (primarily useful in testsuites):
+ *     error_free_or_abort(&err);
+ *
  * Pass an existing error to the caller:
  *     error_propagate(errp, err);
  * where Error **errp is a parameter, by convention the last one.
@@ -189,6 +193,11 @@ Error *error_copy(const Error *err);
  */
 void error_free(Error *err);
 
+/*
+ * Convenience function to assert that *@errp is set, then silently free it.
+ */
+void error_free_or_abort(Error **errp);
+
 /*
  * Convenience function to error_report() and free @err.
  */

tests/test-qmp-commands.c

@@ -225,8 +225,7 @@ static void test_dealloc_partial(void)
     assert(ud2->dict1 == NULL);
 
     /* confirm & release construction error */
-    assert(err != NULL);
-    error_free(err);
+    error_free_or_abort(&err);
 
     /* tear down partial object */
     qapi_free_UserDefTwo(ud2);

tests/test-qmp-input-strict.c

@@ -180,8 +180,7 @@ static void test_validate_fail_struct(TestInputVisitorData *data,
     v = validate_test_init(data, "{ 'integer': -42, 'boolean': true, 'string': 'foo', 'extra': 42 }");
 
     visit_type_TestStruct(v, &p, NULL, &err);
-    g_assert(err);
-    error_free(err);
+    error_free_or_abort(&err);
     if (p) {
         g_free(p->string);
     }
@@ -198,8 +197,7 @@ static void test_validate_fail_struct_nested(TestInputVisitorData *data,
     v = validate_test_init(data, "{ 'string0': 'string0', 'dict1': { 'string1': 'string1', 'dict2': { 'userdef1': { 'integer': 42, 'string': 'string', 'extra': [42, 23, {'foo':'bar'}] }, 'string2': 'string2'}}}");
 
     visit_type_UserDefTwo(v, &udp, NULL, &err);
-    g_assert(err);
-    error_free(err);
+    error_free_or_abort(&err);
     qapi_free_UserDefTwo(udp);
 }
 
@@ -213,8 +211,7 @@ static void test_validate_fail_list(TestInputVisitorData *data,
     v = validate_test_init(data, "[ { 'string': 'string0', 'integer': 42 }, { 'string': 'string1', 'integer': 43 }, { 'string': 'string2', 'integer': 44, 'extra': 'ggg' } ]");
 
     visit_type_UserDefOneList(v, &head, NULL, &err);
-    g_assert(err);
-    error_free(err);
+    error_free_or_abort(&err);
     qapi_free_UserDefOneList(head);
 }
 
@@ -229,8 +226,7 @@ static void test_validate_fail_union_native_list(TestInputVisitorData *data,
                            "{ 'type': 'integer', 'data' : [ 'string' ] }");
 
     visit_type_UserDefNativeListUnion(v, &tmp, NULL, &err);
-    g_assert(err);
-    error_free(err);
+    error_free_or_abort(&err);
     qapi_free_UserDefNativeListUnion(tmp);
 }
 
@@ -244,8 +240,7 @@ static void test_validate_fail_union_flat(TestInputVisitorData *data,
     v = validate_test_init(data, "{ 'string': 'c', 'integer': 41, 'boolean': true }");
 
     visit_type_UserDefFlatUnion(v, &tmp, NULL, &err);
-    g_assert(err);
-    error_free(err);
+    error_free_or_abort(&err);
     qapi_free_UserDefFlatUnion(tmp);
 }
 
@@ -260,8 +255,7 @@ static void test_validate_fail_union_flat_no_discrim(TestInputVisitorData *data,
     v = validate_test_init(data, "{ 'integer': 42, 'string': 'c', 'string1': 'd', 'string2': 'e' }");
 
     visit_type_UserDefFlatUnion2(v, &tmp, NULL, &err);
-    g_assert(err);
-    error_free(err);
+    error_free_or_abort(&err);
     qapi_free_UserDefFlatUnion2(tmp);
 }
 
@@ -275,8 +269,7 @@ static void test_validate_fail_alternate(TestInputVisitorData *data,
     v = validate_test_init(data, "3.14");
 
     visit_type_UserDefAlternate(v, &tmp, NULL, &err);
-    g_assert(err);
-    error_free(err);
+    error_free_or_abort(&err);
     qapi_free_UserDefAlternate(tmp);
 }
 

tests/test-qmp-input-visitor.c

@@ -111,8 +111,7 @@ static void test_visitor_in_int_overflow(TestInputVisitorData *data,
     v = visitor_input_test_init(data, "%f", DBL_MAX);
 
     visit_type_int(v, &res, NULL, &err);
-    g_assert(err);
-    error_free(err);
+    error_free_or_abort(&err);
 }
 
 static void test_visitor_in_bool(TestInputVisitorData *data,
@@ -319,9 +318,7 @@ static void test_visitor_in_alternate(TestInputVisitorData *data,
 
     v = visitor_input_test_init(data, "false");
     visit_type_UserDefAlternate(v, &tmp, NULL, &err);
-    g_assert(err);
-    error_free(err);
-    err = NULL;
+    error_free_or_abort(&err);
     qapi_free_UserDefAlternate(tmp);
 }
 
@@ -341,9 +338,7 @@ static void test_visitor_in_alternate_number(TestInputVisitorData *data,
 
     v = visitor_input_test_init(data, "42");
     visit_type_AltStrBool(v, &asb, NULL, &err);
-    g_assert(err);
-    error_free(err);
-    err = NULL;
+    error_free_or_abort(&err);
     qapi_free_AltStrBool(asb);
 
     /* FIXME: Order of alternate should not affect semantics; asn should
@@ -352,9 +347,7 @@ static void test_visitor_in_alternate_number(TestInputVisitorData *data,
     visit_type_AltStrNum(v, &asn, NULL, &err);
     /* FIXME g_assert_cmpint(asn->type, == ALT_STR_NUM_KIND_N); */
     /* FIXME g_assert_cmpfloat(asn->u.n, ==, 42); */
-    g_assert(err);
-    error_free(err);
-    err = NULL;
+    error_free_or_abort(&err);
     qapi_free_AltStrNum(asn);
 
     v = visitor_input_test_init(data, "42");
@@ -385,9 +378,7 @@ static void test_visitor_in_alternate_number(TestInputVisitorData *data,
 
     v = visitor_input_test_init(data, "42.5");
     visit_type_AltStrBool(v, &asb, NULL, &err);
-    g_assert(err);
-    error_free(err);
-    err = NULL;
+    error_free_or_abort(&err);
     qapi_free_AltStrBool(asb);
 
     v = visitor_input_test_init(data, "42.5");
@@ -404,9 +395,7 @@ static void test_visitor_in_alternate_number(TestInputVisitorData *data,
 
     v = visitor_input_test_init(data, "42.5");
     visit_type_AltStrInt(v, &asi, NULL, &err);
-    g_assert(err);
-    error_free(err);
-    err = NULL;
+    error_free_or_abort(&err);
     qapi_free_AltStrInt(asi);
 
     v = visitor_input_test_init(data, "42.5");
@@ -713,12 +702,11 @@ static void test_visitor_in_errors(TestInputVisitorData *data,
     v = visitor_input_test_init(data, "{ 'integer': false, 'boolean': 'foo', 'string': -42 }");
 
     visit_type_TestStruct(v, &p, NULL, &err);
-    g_assert(err);
+    error_free_or_abort(&err);
     /* FIXME - a failed parse should not leave a partially-allocated p
      * for us to clean up; this could cause callers to leak memory. */
     g_assert(p->string == NULL);
 
-    error_free(err);
     g_free(p->string);
     g_free(p);
 }

util/error.c

@@ -220,6 +220,13 @@ void error_free(Error *err)
     }
 }
 
+void error_free_or_abort(Error **errp)
+{
+    assert(errp && *errp);
+    error_free(*errp);
+    *errp = NULL;
+}
+
 void error_propagate(Error **dst_errp, Error *local_err)
 {
     if (!local_err) {