env_process: Refactor libvirt version verification step

libvirt version is checked and compared to the required version,
if there's one. That was done in the preprocess and postprocess
functions in virttest.env_process. Write a Setuper subclass that
implements that in the setup method and register the setuper in the
env_process setup_manager.

This is a patch from a larger patch series refactoring the env_process
preprocess and postprocess functions. In each of these patches, a
pre/post process step is identified and replaced with a Setuper subclass
so the following can finally be met:
    - Only cleanup steps of successful setup steps are run to avoid
      possible environment corruption or hard to read errors.
    - Running setup/cleanup steps symmetrically during env pre/post
      process.
    - Reduce explicit pre/post process function code length.

Signed-off-by: Beñat Gartzia Arruabarrena <bgartzia@redhat.com>

virttest/env_process.py

@@ -58,6 +58,7 @@
 from virttest.test_setup.requirement_checks import (
     CheckInstalledCMDs,
     CheckKernelVersion,
+    CheckLibvirtVersion,
     CheckQEMUVersion,
     CheckRunningAsRoot,
     CheckVirtioWinVersion,
@@ -1021,26 +1022,13 @@ def preprocess(test, params, env):
     _setup_manager.register(CheckQEMUVersion)
     _setup_manager.register(LogBootloaderVersion)
     _setup_manager.register(CheckVirtioWinVersion)
+    _setup_manager.register(CheckLibvirtVersion)
     _setup_manager.do_setup()
 
     vm_type = params.get("vm_type")
 
     base_dir = data_dir.get_data_dir()
 
-    # Get the Libvirt version
-    if vm_type == "libvirt":
-        libvirt_ver_cmd = params.get(
-            "libvirt_ver_cmd", "libvirtd -V|awk -F' ' '{print $3}'"
-        )
-        try:
-            libvirt_version = a_process.run(
-                libvirt_ver_cmd, shell=True
-            ).stdout_text.strip()
-        except a_process.CmdError:
-            libvirt_version = "Unknown"
-        version_info["libvirt_version"] = str(libvirt_version)
-        LOG.debug("KVM userspace version(libvirt): %s" % libvirt_version)
-
     # Write it as a keyval
     test.write_test_keyval(version_info)
 

virttest/test_setup/requirement_checks.py

@@ -198,3 +198,24 @@ def setup(self):
 
     def cleanup(self):
         pass
+
+
+class CheckLibvirtVersion(Setuper):
+    def setup(self):
+        # Get the Libvirt version
+        vm_type = self.params.get("vm_type")
+        if vm_type == "libvirt":
+            libvirt_ver_cmd = self.params.get(
+                "libvirt_ver_cmd", "libvirtd -V|awk -F' ' '{print $3}'"
+            )
+            try:
+                libvirt_version = a_process.run(
+                    libvirt_ver_cmd, shell=True
+                ).stdout_text.strip()
+            except a_process.CmdError:
+                libvirt_version = "Unknown"
+            env_process.version_info["libvirt_version"] = str(libvirt_version)
+            LOG.debug("KVM userspace version(libvirt): %s" % libvirt_version)
+
+    def cleanup(self):
+        pass