use emplace_back() instead of push_back()

unittest/force-styles/test_config_reader.cpp

@@ -86,7 +86,7 @@ void TestConfigReader::prerequisites(const yaml_event_t &event)
     while (1) {
         data >> key >> value;
         if (data.eof()) break;
-        config.prerequisites.push_back(std::make_pair(key, value));
+        config.prerequisites.emplace_back(key, value);
     }
 }
 
@@ -141,7 +141,7 @@ void TestConfigReader::extract(const yaml_event_t &event)
     while (1) {
         data >> name >> value;
         if (data.eof()) break;
-        config.extract.push_back(make_pair(name, value));
+        config.extract.emplace_back(name, value);
     }
 }
 

unittest/force-styles/test_pair_style.cpp

@@ -1252,7 +1252,7 @@ TEST(PairStyle, single)
     int argc    = sizeof(args) / sizeof(char *);
 
     // need to add this dependency
-    test_config.prerequisites.push_back(std::make_pair("atom", "full"));
+    test_config.prerequisites.emplace_back("atom", "full");
 
     // create a LAMMPS instance with standard settings to detect the number of atom types
     if (!verbose) ::testing::internal::CaptureStdout();