test: refactor csc tests to handle empty csc ConfigMaps

Initially, we expect default CSC ConfigMaps to contain default values and
so we read these default values e.g `replicas` to perform csc persistence tests

But with our new approach, default CSC ConfigMaps are deployed
without default service values, so we need to adapt the test accordingly

tests/post/features/service_configuration.feature

@@ -4,7 +4,7 @@ Feature: Cluster and Services Configurations
         Given the Kubernetes API is available
         And pods with label 'app.kubernetes.io/name=dex' are 'Ready'
         And we have 2 running pod labeled 'app.kubernetes.io/name=dex' in namespace 'metalk8s-auth'
-        And we have a 'metalk8s-dex-config' CSC in namespace 'metalk8s-auth' with 'spec.deployment.replicas' equal to '2'
+        And we have a 'metalk8s-dex-config' CSC in namespace 'metalk8s-auth'
         When we update 'metalk8s-dex-config' CSC in namespace 'metalk8s-auth' 'spec.deployment.replicas' to '3'
         And we apply the 'metalk8s.addons.dex.deployed' salt state
         Then we have '3' at 'status.available_replicas' for 'dex' Deployment in namespace 'metalk8s-auth'

tests/post/steps/test_service_configuration.py

@@ -11,6 +11,20 @@
 from tests import utils
 
 
+# Constants {{{
+
+
+DEFAULT_CSC_CONFIG_YAML = """
+apiVersion: addons.metalk8s.scality.com
+kind: DexConfig
+spec:
+  deployment:
+    replicas: {replicas}
+"""
+
+
+# }}}
+
 # Fixtures {{{
 
 
@@ -42,15 +56,12 @@ def test_service_config_propagation(host):
 
 
 @given(parsers.parse(
-    "we have a '{name}' CSC in namespace '{namespace}' with "
-    "'{path}' equal to '{value}'"))
+    "we have a '{name}' CSC in namespace '{namespace}'"))
 def check_csc_configuration(
     k8s_client,
     csc,
     name,
     namespace,
-    path,
-    value
 ):
     csc_response = csc.get(name, namespace)
 
@@ -61,12 +72,6 @@ def check_csc_configuration(
     )
 
     csc_obj = csc.load(csc_response, name, namespace)
-    response_value = utils.get_dict_element(csc_obj, path)
-
-    assert literal_eval(value) == response_value, (
-        "Expected value {} for key {} in ConfigMap {} found in namespace {}, "
-        "got {}".format(value, path, name, namespace, response_value)
-    )
     return dict(csc_obj=csc_obj)
 
 
@@ -88,14 +93,13 @@ def update_service_configuration(
     value
 ):
 
-    full_csc = csc.get(name, namespace)
-    csc_obj = utils.set_dict_element(
-        csc.load(full_csc, name, namespace), path, literal_eval(value)
+    csc_from_yaml = yaml.safe_load(
+        DEFAULT_CSC_CONFIG_YAML.format(replicas=value)
     )
     patch = {
         'data': {
             'config.yaml': yaml.safe_dump(
-                csc_obj, default_flow_style=False
+                csc_from_yaml, default_flow_style=False
             )
         }
     }