test: add more tests to configuration

src/config.rs

@@ -197,6 +197,26 @@ mod tests {
         config
     }
 
+    #[test]
+    fn configuration_should_have_default_values() {
+        use crate::Configuration;
+
+        let configuration = Configuration::default();
+
+        let toml = toml::to_string(&configuration).expect("Could not encode TOML value");
+
+        assert_eq!(toml, default_config_toml());
+    }
+
+    #[test]
+    fn configuration_should_contain_the_external_ip() {
+        use crate::Configuration;
+
+        let configuration = Configuration::default();
+
+        assert_eq!(configuration.external_ip, Option::Some(String::from("0.0.0.0")));
+    }
+
     #[test]
     fn configuration_should_be_saved_in_a_toml_config_file() {
         use std::env;
@@ -253,4 +273,13 @@ mod tests {
 
         assert_eq!(configuration, Configuration::default());
     }
+
+    #[test]
+    fn configuration_error_could_be_displayed() {
+        use crate::ConfigurationError;
+
+        let error = ConfigurationError::TrackerModeIncompatible;
+
+        assert_eq!(format!("{}", error), "TrackerModeIncompatible");
+    }
 }