Use explicit for single param constructors

Author: joto

tests/common-cleanup.hpp

@@ -26,7 +26,8 @@ namespace testing::cleanup {
 class file_t
 {
 public:
-    file_t(std::string const &filename, bool remove_on_construct = true)
+    explicit file_t(std::string const &filename,
+                    bool remove_on_construct = true)
     : m_filename(filename)
     {
         if (remove_on_construct) {

tests/common-pg.hpp

@@ -37,7 +37,7 @@ namespace testing::pg {
 class conn_t : public pg_conn_t
 {
 public:
-    conn_t(connection_params_t const &connection_params)
+    explicit conn_t(connection_params_t const &connection_params)
     : pg_conn_t(connection_params, "test")
     {
     }