Test parameter-retrieval failures

Author: knoepfel

test/configuration.cpp

@@ -2,9 +2,24 @@
 
 #include "boost/json.hpp"
 #include "catch2/catch_test_macros.hpp"
+#include "catch2/matchers/catch_matchers_string.hpp"
 
 using namespace phlex::experimental;
 
+TEST_CASE("Check parameter-retrieval errors", "[config]")
+{
+  boost::json::object underlying_config;
+  underlying_config["b"] = 2.5;
+  configuration const config{underlying_config};
+
+  CHECK(config.keys() == std::vector<std::string>{"b"});
+
+  CHECK_THROWS_WITH(config.get<int>("a"),
+                    Catch::Matchers::ContainsSubstring("Error retrieving parameter 'a'"));
+  CHECK_THROWS_WITH(config.get<std::string>("b"),
+                    Catch::Matchers::ContainsSubstring("Error retrieving parameter 'b'"));
+}
+
 TEST_CASE("Retrieve value that is a configuration object", "[config]")
 {
   boost::json::object underlying_config;