tests: qemublock: Add tests for cross-snapshot incremental backups

Signed-off-by: NPeter Krempa <pkrempa@redhat.com>
Reviewed-by: NEric Blake <eblake@redhat.com>

tests/qemublocktest.c

@@ -939,6 +939,10 @@ mymain(void)
     TEST_BACKUP_BITMAP_CALCULATE("basic-intermediate", bitmapSourceChain, "d", "basic");
     TEST_BACKUP_BITMAP_CALCULATE("basic-deep", bitmapSourceChain, "a", "basic");
 
+    TEST_BACKUP_BITMAP_CALCULATE("snapshot-flat", bitmapSourceChain, "current", "snapshots");
+    TEST_BACKUP_BITMAP_CALCULATE("snapshot-intermediate", bitmapSourceChain, "d", "snapshots");
+    TEST_BACKUP_BITMAP_CALCULATE("snapshot-deep", bitmapSourceChain, "a", "snapshots");
+
  cleanup:
     virHashFree(diskxmljsondata.schema);
     qemuTestDriverFree(&driver);

tests/qemublocktestdata/backupmerge/snapshot-deep-out.json

+[
+  {
+    "node": "libvirt-1-format",
+    "name": "current"
+  },
+  {
+    "node": "libvirt-1-format",
+    "name": "d"
+  },
+  {
+    "node": "libvirt-2-format",
+    "name": "d"
+  },
+  {
+    "node": "libvirt-2-format",
+    "name": "c"
+  },
+  {
+    "node": "libvirt-3-format",
+    "name": "c"
+  },
+  {
+    "node": "libvirt-3-format",
+    "name": "b"
+  },
+  {
+    "node": "libvirt-3-format",
+    "name": "a"
+  },
+  {
+    "node": "libvirt-4-format",
+    "name": "a"
+  },
+  {
+    "node": "libvirt-5-format",
+    "name": "a"
+  }
+]

tests/qemublocktestdata/backupmerge/snapshot-flat-out.json

+[
+  {
+    "node": "libvirt-1-format",
+    "name": "current"
+  }
+]

tests/qemublocktestdata/backupmerge/snapshot-intermediate-out.json

+[
+  {
+    "node": "libvirt-1-format",
+    "name": "current"
+  },
+  {
+    "node": "libvirt-1-format",
+    "name": "d"
+  },
+  {
+    "node": "libvirt-2-format",
+    "name": "d"
+  }
+]