[eriknstr]

Looking at it that way, I think it's possible to make "expect" more comfortable to read by how you phrase your error messages.

Instead of

    let mut file = File::open("conf.json")
        .expect("could not open file");

and

    let config: Value = serde::from_reader(file)
        .expect("config has invalid json");

and

    let jenkins_server = config.get("jenkins_server")
        .expect("jenkins_server key not in config")
        .as_str()
        .expect("jenkins_server key is not a string");

One could write

    let mut file = File::open("conf.json")
        .expect("Need to be able to open file `conf.json'.");

and

    let config: Value = serde::from_reader(file)
        .expect("The file `conf.json' must contain valid JSON.");

and

    let jenkins_server = config.get("jenkins_server")
        .expect("The config must have a key named `jenkins_server'.")
        .as_str()
        .expect("The config value of `jenkins_server' must be a string.");

Something like that.

[erickt]

That is a good point. I'm going to have to start being more positive in my expectations :)