CLI

[ilslv]

In v0.10.0 CLI was preserved as is with error messages for unsupported options. But we want to rework it for more flexibility. Based on Java and JS I've came up with new CLI design:

$ cargo test -- --help
cucumber 0.11.0
Brendan Molloy <brendan@bbqsrc.net>,
Ilya Solovyiov <ilya.solovyiov@gmail.com>,
Kai Ren <tyranron@gmail.com>

USAGE:
    cargo test -- [FLAGS] [OPTIONS]

FLAGS:
    -h, --help       Prints this message
    -v               Sets the level of verbosity
    -V, --version    Prints version information

OPTIONS:
    -c, --colors                 <auto/enable/disable>    Indicates, whether output should be colored or not. Default: auto     
    -f, --feature                <FILES>                  Comma separated paths to feature files. Example: path/*/example.feature, other/to/
    -n, --name, --scenario-name  <REGEX>                  Filters scenarios based on name.
    -t, --tags, --scenario-tags  <TAGEXPR>                Filters scenarios based on tag expression. Example: @smoke and not @slow
    --concurrent                 <INT>                    Number of concurrent scenarios.
    --fail_fast                  <BOOL>                   Abort the run on first failure. Default: false

Cucumber tag expressions reference

[ilslv]

Also we should consider enabling or disabling some cli options based on specific Parser, Runner or Writer impls. Related to #56 (comment) #140

[ilslv]

Discussed:

We want then every swappable part (like Parser, Runner and Writer) to have it's own strongly-typed set CLI arguments. This can be done by using #[clap(flatten)] with a generic clap::Arg provider. The only problem is that at the time clap derive-macros doesn't support generic arguments

• Deriving for generic structs clap-rs/clap#2769

But structopt recently have added basic implementation of this feature:

• add basic support for generic structs and enums TeXitoi/structopt#483

So the plan is to try jumping back to latest stable version of the clap and use structopt for strong-typing. If that doesn't work out, we'll have to use some custom trait with dynamic adding/extracting from clap::App.

Long term goal is still to use only clap crate with it's own derive-macros.