Add tests & Service's Configuration has optional fields that shouldn't be optional (#4842)

Related to #4776 
Related to https://github.com/paritytech/polkadot/pull/832

To summarize the changes:
1. I did not manage to validate with types the service's Configuration. But I did reduce the possibility of errors by moving all the "fill" functions to their respective structopts
2. I split params.rs to multiple modules: one module params for just CLI parameters and one module commands for CLI subcommands (and RunCmd). Every command and params are in their own file so things are grouped better together and easier to remove
3. I removed the run and run_subcommand helpers as they are not helping much anymore. Running a command is always a set of 3 commands: 1. init 2. update config 3. run. This still allow the user to change the config before arguments get parsed or right after.
4. I added tests for all subcommands.
5. [deleted]

Overall the aim is to improve the situation with the Configuration and the optional parameters, add tests, make the API more consistent and simpler.

substrate/client/cli/src/params/network_configuration_params.rs

@@ -0,0 +1,160 @@
+// Copyright 2018-2020 Parity Technologies (UK) Ltd.
+// This file is part of Substrate.
+
+// Substrate is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+
+// Substrate is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License
+// along with Substrate.  If not, see <http://www.gnu.org/licenses/>.
+
+use std::path::PathBuf;
+use std::iter;
+use std::net::Ipv4Addr;
+use structopt::StructOpt;
+use sc_network::{
+	config::{NonReservedPeerMode, TransportConfig}, multiaddr::Protocol,
+};
+use sc_service::{Configuration, RuntimeGenesis};
+
+use crate::error;
+use crate::params::node_key_params::NodeKeyParams;
+
+/// Parameters used to create the network configuration.
+#[derive(Debug, StructOpt, Clone)]
+pub struct NetworkConfigurationParams {
+	/// Specify a list of bootnodes.
+	#[structopt(long = "bootnodes", value_name = "URL")]
+	pub bootnodes: Vec<String>,
+
+	/// Specify a list of reserved node addresses.
+	#[structopt(long = "reserved-nodes", value_name = "URL")]
+	pub reserved_nodes: Vec<String>,
+
+	/// Whether to only allow connections to/from reserved nodes.
+	///
+	/// If you are a validator your node might still connect to other validator
+	/// nodes regardless of whether they are defined as reserved nodes.
+	#[structopt(long = "reserved-only")]
+	pub reserved_only: bool,
+
+	/// Specify a list of sentry node public addresses.
+	#[structopt(
+		long = "sentry-nodes",
+		value_name = "URL",
+		conflicts_with_all = &[ "sentry" ]
+	)]
+	pub sentry_nodes: Vec<String>,
+
+	/// Listen on this multiaddress.
+	#[structopt(long = "listen-addr", value_name = "LISTEN_ADDR")]
+	pub listen_addr: Vec<String>,
+
+	/// Specify p2p protocol TCP port.
+	///
+	/// Only used if --listen-addr is not specified.
+	#[structopt(long = "port", value_name = "PORT")]
+	pub port: Option<u16>,
+
+	/// Forbid connecting to private IPv4 addresses (as specified in
+	/// [RFC1918](https://tools.ietf.org/html/rfc1918)), unless the address was passed with
+	/// `--reserved-nodes` or `--bootnodes`.
+	#[structopt(long = "no-private-ipv4")]
+	pub no_private_ipv4: bool,
+
+	/// Specify the number of outgoing connections we're trying to maintain.
+	#[structopt(long = "out-peers", value_name = "COUNT", default_value = "25")]
+	pub out_peers: u32,
+
+	/// Specify the maximum number of incoming connections we're accepting.
+	#[structopt(long = "in-peers", value_name = "COUNT", default_value = "25")]
+	pub in_peers: u32,
+
+	/// Disable mDNS discovery.
+	///
+	/// By default, the network will use mDNS to discover other nodes on the
+	/// local network. This disables it. Automatically implied when using --dev.
+	#[structopt(long = "no-mdns")]
+	pub no_mdns: bool,
+
+	/// Maximum number of peers to ask the same blocks in parallel.
+	///
+	/// This allows downlading announced blocks from multiple peers. Decrease to save
+	/// traffic and risk increased latency.
+	#[structopt(long = "max-parallel-downloads", value_name = "COUNT", default_value = "5")]
+	pub max_parallel_downloads: u32,
+
+	#[allow(missing_docs)]
+	#[structopt(flatten)]
+	pub node_key_params: NodeKeyParams,
+
+	/// Experimental feature flag.
+	#[structopt(long = "use-yamux-flow-control")]
+	pub use_yamux_flow_control: bool,
+}
+
+impl NetworkConfigurationParams {
+	/// Fill the given `NetworkConfiguration` by looking at the cli parameters.
+	pub fn update_config<G, E>(
+		&self,
+		mut config: &mut Configuration<G, E>,
+		config_path: PathBuf,
+		client_id: String,
+		is_dev: bool,
+	) -> error::Result<()>
+	where
+		G: RuntimeGenesis,
+	{
+		config.network.boot_nodes.extend(self.bootnodes.clone());
+		config.network.config_path = Some(config_path.clone());
+		config.network.net_config_path = Some(config_path.clone());
+
+		config.network.reserved_nodes.extend(self.reserved_nodes.clone());
+		if self.reserved_only {
+			config.network.non_reserved_mode = NonReservedPeerMode::Deny;
+		}
+
+		config.network.sentry_nodes.extend(self.sentry_nodes.clone());
+
+		for addr in self.listen_addr.iter() {
+			let addr = addr.parse().ok().ok_or(error::Error::InvalidListenMultiaddress)?;
+			config.network.listen_addresses.push(addr);
+		}
+
+		if config.network.listen_addresses.is_empty() {
+			let port = match self.port {
+				Some(port) => port,
+				None => 30333,
+			};
+
+			config.network.listen_addresses = vec![
+				iter::once(Protocol::Ip4(Ipv4Addr::new(0, 0, 0, 0)))
+					.chain(iter::once(Protocol::Tcp(port)))
+					.collect()
+			];
+		}
+
+		config.network.client_version = client_id;
+		self.node_key_params.update_config(&mut config, Some(&config_path))?;
+
+		config.network.in_peers = self.in_peers;
+		config.network.out_peers = self.out_peers;
+
+		config.network.transport = TransportConfig::Normal {
+			enable_mdns: !is_dev && !self.no_mdns,
+			allow_private_ipv4: !self.no_private_ipv4,
+			wasm_external_transport: None,
+			use_yamux_flow_control: self.use_yamux_flow_control,
+		};
+
+		config.network.max_parallel_downloads = self.max_parallel_downloads;
+
+		Ok(())
+	}
+}