added two qemu-img resize tests

1. Verify qemu-img resize increase on raw format.
2. Verify qemu-img resize shrink on raw format.
Signed-off-by: NHaotong Chen <hachen@redhat.com>

qemu/tests/cfg/resize_raw_img.cfg

+- resize_raw_img:
+    only raw
+    virt_test_type = qemu
+    kill_vm = yes
+    start_vm = no
+    force_create_image = no
+    type = resize_raw_img
+    images = "test"
+    image_format_test = raw
+    image_name_test = images/test
+    variants:
+        - increase_size:
+            # These two params must be provided to calculate size changes.
+            # You can change size_changes based on your cases.
+            image_size_test = 10G
+            size_changes = "+1G"
+        - shrink_size:
+            required_qemu = [2.12.0, )
+            image_size_test = 10G
+            size_changes = "-2G"

qemu/tests/resize_raw_img.py

+import json
+import logging
+
+from virttest import data_dir
+from virttest import error_context
+from virttest import utils_numeric
+from virttest.qemu_storage import QemuImg
+
+
+@error_context.context_aware
+def run(test, params, env):
+    """
+    A 'qemu-img' resize test.
+
+    1.create a raw image
+    2.change the raw image size * n
+    3.verify resize * n
+
+    :param test: Qemu test object
+    :param params: Dictionary with the test parameters
+    :param env: Dictionary with test environment.
+    """
+    def _sum_size_changes(size_changes):
+        """
+        Sum the list of size changes.
+
+        :param size_changes: list of size changes
+        """
+        res = []
+        for change in size_changes:
+            s = int(utils_numeric.normalize_data_size(change, "B")
+                    ) * (-1 if '-' in change else 1)
+            res.append(s)
+        return sum(res)
+
+    def _verify_resize(img_size, expected_size):
+        """Verify the image size is as expected after resize."""
+        logging.info("Verify the size of  %s is %s." %
+                     (img.image_filename, expected_size))
+        if img_size != expected_size:
+            test.fail("Got image virtual size: %s, should be: %s." %
+                      (img_size, expected_size))
+
+    def _resize(size_changes):
+        """Resize the image and verify its size."""
+        for idx, size in enumerate(size_changes):
+            logging.info("Resize the raw image %s %s." % (img.image_filename,
+                                                          size))
+            shrink = True if "-" in size else False
+            img.resize(size, shrink=shrink)
+
+            img_size = json.loads(img.info(output="json"))["virtual-size"]
+            expected_size = (int(utils_numeric.normalize_data_size(
+                params["image_size_test"], "B")) +
+                _sum_size_changes(size_changes[:idx + 1]))
+            _verify_resize(img_size, expected_size)
+
+    img_param = params.object_params('test')
+    img = QemuImg(img_param, data_dir.get_data_dir(), 'test')
+    size_changes = params["size_changes"].split()
+
+    logging.info("Create a raw image %s." % img.image_filename)
+    img.create(img_param)
+
+    _resize(size_changes)