tests: fix several instances of the most vexing parse

Change-Id: I6195bb5cd3ea0fb85e4e10a78319936f0fe5f3f3
Refs: #4545
diff --git a/tests/unit-tests/security/signature-sha256-with-ecdsa.t.cpp b/tests/unit-tests/security/signature-sha256-with-ecdsa.t.cpp
index edc15d7..658b1c2 100644
--- a/tests/unit-tests/security/signature-sha256-with-ecdsa.t.cpp
+++ b/tests/unit-tests/security/signature-sha256-with-ecdsa.t.cpp
@@ -77,7 +77,7 @@
   Block sigValueBlock(sigValue, sizeof(sigValue));
 
   Signature sig(sigInfoBlock, sigValueBlock);
-  BOOST_CHECK_NO_THROW(SignatureSha256WithEcdsa(sig));
+  BOOST_CHECK_NO_THROW(SignatureSha256WithEcdsa{sig});
   BOOST_CHECK_NO_THROW(sig.getKeyLocator());
 }