test: fix pytest.raises error text warnings

Dont pass "" as match text. Given that a common paradigm throughout
the tests is:
text = expected text
None = no exception
"" = exception with any text

Workaround pytest's expectations here.

Author: TheRealFalcon

tests/unittests/config/test_cc_package_update_upgrade_install.py

@@ -326,5 +326,7 @@ class TestPackageUpdateUpgradeSchema:
     )
     @skipUnlessJsonSchema()
     def test_schema_validation(self, config, error_msg):
-        with pytest.raises(SchemaValidationError, match=error_msg):
+        with pytest.raises(
+            SchemaValidationError, match=error_msg if error_msg else None
+        ):
             validate_cloudconfig_schema(config, get_schema(), strict=True)

tests/unittests/config/test_cc_power_state_change.py

@@ -219,5 +219,7 @@ def test_schema_validation(self, config, error_msg):
         if error_msg is None:
             validate_cloudconfig_schema(config, get_schema(), strict=True)
         else:
-            with pytest.raises(SchemaValidationError, match=error_msg):
+            with pytest.raises(
+                SchemaValidationError, match=error_msg if error_msg else None
+            ):
                 validate_cloudconfig_schema(config, get_schema(), strict=True)

tests/unittests/config/test_cc_rsyslog.py

@@ -270,7 +270,9 @@ def test_schema_validation(self, config, error_msg):
         if error_msg is None:
             validate_cloudconfig_schema(config, get_schema(), strict=True)
         else:
-            with pytest.raises(SchemaValidationError, match=error_msg):
+            with pytest.raises(
+                SchemaValidationError, match=error_msg if error_msg else None
+            ):
                 validate_cloudconfig_schema(config, get_schema(), strict=True)
 
 

tests/unittests/config/test_cc_snap.py

@@ -288,7 +288,9 @@ def test_schema_validation(self, config, error_msg):
         if error_msg is None:
             validate_cloudconfig_schema(config, get_schema(), strict=True)
         else:
-            with pytest.raises(SchemaValidationError, match=error_msg):
+            with pytest.raises(
+                SchemaValidationError, match=error_msg if error_msg else None
+            ):
                 validate_cloudconfig_schema(config, get_schema(), strict=True)