tests: refactor common test infrastructure and fixtures

Change-Id: I597c11130eefa2cc2846ee6655c85dc04f2f22ef
diff --git a/tests/unit/security/validator-config/rule.t.cpp b/tests/unit/security/validator-config/rule.t.cpp
index 75eb6dc..04c6e8d 100644
--- a/tests/unit/security/validator-config/rule.t.cpp
+++ b/tests/unit/security/validator-config/rule.t.cpp
@@ -40,7 +40,7 @@
 BOOST_AUTO_TEST_SUITE(ValidatorConfig)
 
 template<class Packet>
-class RuleFixture : public IdentityManagementFixture
+class RuleFixture : public KeyChainFixture
 {
 public:
   RuleFixture()