test: utils: Add helpers for automatic numbering of test cases

Adding or reordering test cases is usually a pain due to static test
case names that are then passed to virtTestRun(). To ease the numbering
of test cases, this patch adds two simple helpers that generate the test
names according to the order they are run. The test name can be
configured via the reset function.

This will allow us to freely add test cases in middle of test groups
without the need to re-number the rest of test cases.

tests/testutils.c

@@ -986,3 +986,55 @@ virDomainXMLOptionPtr virTestGenericDomainXMLConfInit(void)
                                  &virTestGenericPrivateDataCallbacks,
                                  NULL);
 }
+
+
+static int virtTestCounter;
+static char virtTestCounterStr[128];
+static char *virtTestCounterPrefixEndOffset;
+
+
+/**
+ * virtTestCounterReset:
+ * @prefix: name of the test group
+ *
+ * Resets the counter and sets up the test group name to use with
+ * virtTestCounterNext(). This function is not thread safe.
+ *
+ * Note: The buffer for the assembled message is 128 bytes long. Longer test
+ * case names (including the number index) will be silently truncated.
+ */
+void
+virtTestCounterReset(const char *prefix)
+{
+    virtTestCounter = 0;
+
+    ignore_value(virStrcpyStatic(virtTestCounterStr, prefix));
+    virtTestCounterPrefixEndOffset = strchrnul(virtTestCounterStr, '\0');
+}
+
+
+/**
+ * virtTestCounterNext:
+ *
+ * This function is designed to ease test creation and reordering by adding
+ * a way to do automagic test case numbering.
+ *
+ * Returns string consisting of test name prefix configured via
+ * virtTestCounterReset() and a number that increments in every call of this
+ * function. This function is not thread safe.
+ *
+ * Note: The buffer for the assembled message is 128 bytes long. Longer test
+ * case names (including the number index) will be silently truncated.
+ */
+const char
+*virtTestCounterNext(void)
+{
+    size_t len = ARRAY_CARDINALITY(virtTestCounterStr);
+
+    /* calculate length of the rest of the string */
+    len -= (virtTestCounterPrefixEndOffset - virtTestCounterStr);
+
+    snprintf(virtTestCounterPrefixEndOffset, len, "%d", ++virtTestCounter);
+
+    return virtTestCounterStr;
+}

tests/testutils.h

@@ -82,6 +82,9 @@ char *virtTestLogContentAndReset(void);
 
 void virtTestQuiesceLibvirtErrors(bool always);
 
+void virtTestCounterReset(const char *prefix);
+const char *virtTestCounterNext(void);
+
 int virtTestMain(int argc,
                  char **argv,
                  int (*func)(void));