utest: Fix test case SignatureTest.TestSignatureVerify()

The unit test case SignatureTest.TestSignatureVerify() passes
with default config.
But when `verify-full-signature` is enabled, the test case fails.

resolved: openbmc/phosphor-bmc-code-mgmt#9

Tested: Unit Test successfully when `verify-full-signature` is
enabled.

Signed-off-by: George Liu <liuxiwei@inspur.com>
Change-Id: Ia600690ea26ca3559f1e9f2049283880ddf95a4d
diff --git a/test/utest.cpp b/test/utest.cpp
index 97d2ea4..40f7ea8 100644
--- a/test/utest.cpp
+++ b/test/utest.cpp
@@ -226,6 +226,15 @@
         command(opensslCmd + pkeyFile + " -out " + pubkeyFile + ".sig " +
                 pubkeyFile);
 
+#ifdef WANT_SIGNATURE_FULL_VERIFY
+        std::string fullFile = extractPath.string() + "/" + "image-full";
+        command("cat " + kernelFile + ".sig " + rofsFile + ".sig " + rwfsFile +
+                ".sig " + ubootFile + ".sig " + manifestFile + ".sig " +
+                pubkeyFile + ".sig > " + fullFile);
+        command(opensslCmd + pkeyFile + " -out " + fullFile + ".sig " +
+                fullFile);
+#endif
+
         signature = std::make_unique<Signature>(extractPath, signedConfPath);
     }
     virtual void TearDown()