test treewide: apply test names best practices

1. test suite names are usually related to the function under tests, not
the whole source or header file
2. test case names should be verbose and describe the high level
behavior

This commits also splits test cases when they are for different
functions, and merges test cases when they are very similar.

Reference:
1. https://github.com/google/googletest/tree/main/googletest/samples
2. https://testing.googleblog.com/2007/02/tott-naming-unit-tests-responsibly.html

Signed-off-by: Nan Zhou <nanzhoumails@gmail.com>
Change-Id: I498cb2076bbaa9f0829f50bca45a2e38a6f4ab7d
diff --git a/redfish-core/ut/registries_test.cpp b/redfish-core/ut/registries_test.cpp
index c324fee..758d8b3 100644
--- a/redfish-core/ut/registries_test.cpp
+++ b/redfish-core/ut/registries_test.cpp
@@ -7,7 +7,7 @@
 namespace
 {
 
-TEST(RedfishRegistries, fillMessageArgs)
+TEST(FillMessageArgs, ArgsAreFilledCorrectly)
 {
     std::string toFill("%1");
     fillMessageArgs({{"foo"}}, toFill);