Add test for empty required rule configuration fields

The tool output and rules list assume that the text in the required rule configuration fields is present. In cases where
it is left empty, this assumption might result in strange or misformatted output. At the moment they are all populated,
so that assumption is fine. In the event the test catches an empty field, it can either be fixed or the code changed to
not rely on that field being populated.

Author: per1234

Diff for: internal/rule/ruleconfiguration/ruleconfiguration_test.go

@@ -95,3 +95,13 @@ func TestDuplicateRuleID(t *testing.T) {
 		require.Equalf(t, ruleIndex+1, len(ruleIDMap), "ID %s of rule #%v is a duplicate", ruleConfiguration.ID, ruleIndex)
 	}
 }
+
+func TestRequiredConfigField(t *testing.T) {
+	for _, ruleConfiguration := range ruleconfiguration.Configurations() {
+		assert.NotEmptyf(t, ruleConfiguration.Category, "No category defined for rule %s", ruleConfiguration.ID)
+		assert.NotEmptyf(t, ruleConfiguration.Subcategory, "No subcategory defined for rule %s", ruleConfiguration.ID)
+		assert.NotEmptyf(t, ruleConfiguration.Brief, "No brief defined for rule %s", ruleConfiguration.ID)
+		assert.NotEmptyf(t, ruleConfiguration.Description, "No description defined for rule %s", ruleConfiguration.ID)
+		assert.NotEmptyf(t, ruleConfiguration.MessageTemplate, "No message template defined for rule %s", ruleConfiguration.ID)
+	}
+}