feat(lint): add --rules flag (#6264)

cli/flags.rs

@@ -52,6 +52,7 @@ pub enum DenoSubcommand {
   },
   Lint {
     files: Vec<String>,
+    rules: bool,
   },
   Repl,
   Run {
@@ -592,7 +593,8 @@ fn lint_parse(flags: &mut Flags, matches: &clap::ArgMatches) {
     Some(f) => f.map(String::from).collect(),
     None => vec![],
   };
-  flags.subcommand = DenoSubcommand::Lint { files };
+  let rules = matches.is_present("rules");
+  flags.subcommand = DenoSubcommand::Lint { files, rules };
 }
 
 fn types_subcommand<'a, 'b>() -> App<'a, 'b> {
@@ -913,6 +915,9 @@ fn lint_subcommand<'a, 'b>() -> App<'a, 'b> {
   deno lint --unstable
   deno lint --unstable myfile1.ts myfile2.js
 
+List available rules:
+  deno lint --unstable --rules
+
 Ignore diagnostics on the next line by preceding it with an ignore comment and
 rule name:
   // deno-lint-ignore no-explicit-any
@@ -929,6 +934,11 @@ Ignore linting a file by adding an ignore comment at the top of the file:
 ",
     )
     .arg(unstable_arg())
+    .arg(
+      Arg::with_name("rules")
+        .long("rules")
+        .help("List available rules"),
+    )
     .arg(
       Arg::with_name("files")
         .takes_value(true)
@@ -1658,7 +1668,8 @@ mod tests {
       r.unwrap(),
       Flags {
         subcommand: DenoSubcommand::Lint {
-          files: vec!["script_1.ts".to_string(), "script_2.ts".to_string()]
+          files: vec!["script_1.ts".to_string(), "script_2.ts".to_string()],
+          rules: false,
         },
         unstable: true,
         ..Flags::default()
@@ -1669,7 +1680,23 @@ mod tests {
     assert_eq!(
       r.unwrap(),
       Flags {
-        subcommand: DenoSubcommand::Lint { files: vec![] },
+        subcommand: DenoSubcommand::Lint {
+          files: vec![],
+          rules: false,
+        },
+        unstable: true,
+        ..Flags::default()
+      }
+    );
+
+    let r = flags_from_vec_safe(svec!["deno", "lint", "--unstable", "--rules"]);
+    assert_eq!(
+      r.unwrap(),
+      Flags {
+        subcommand: DenoSubcommand::Lint {
+          files: vec![],
+          rules: true
+        },
         unstable: true,
         ..Flags::default()
       }

cli/lint.rs

@@ -64,6 +64,15 @@ pub async fn lint_files(args: Vec<String>) -> Result<(), ErrBox> {
   Ok(())
 }
 
+pub fn print_rules_list() {
+  let lint_rules = rules::get_recommended_rules();
+
+  println!("Available rules:");
+  for rule in lint_rules {
+    println!(" - {}", rule.code());
+  }
+}
+
 fn create_linter() -> Linter {
   Linter::new(
     "deno-lint-ignore-file".to_string(),

cli/main.rs

@@ -316,7 +316,11 @@ async fn install_command(
     .map_err(ErrBox::from)
 }
 
-async fn lint_command(flags: Flags, files: Vec<String>) -> Result<(), ErrBox> {
+async fn lint_command(
+  flags: Flags,
+  files: Vec<String>,
+  list_rules: bool,
+) -> Result<(), ErrBox> {
   let global_state = GlobalState::new(flags)?;
 
   // TODO(bartlomieju): refactor, it's non-sense to create
@@ -331,6 +335,12 @@ async fn lint_command(flags: Flags, files: Vec<String>) -> Result<(), ErrBox> {
   )?;
 
   state.check_unstable("lint");
+
+  if list_rules {
+    lint::print_rules_list();
+    return Ok(());
+  }
+
   lint::lint_files(files).await
 }
 
@@ -708,7 +718,9 @@ pub fn main() {
     } => {
       install_command(flags, module_url, args, name, root, force).boxed_local()
     }
-    DenoSubcommand::Lint { files } => lint_command(flags, files).boxed_local(),
+    DenoSubcommand::Lint { files, rules } => {
+      lint_command(flags, files, rules).boxed_local()
+    }
     DenoSubcommand::Repl => run_repl(flags).boxed_local(),
     DenoSubcommand::Run { script } => run_command(flags, script).boxed_local(),
     DenoSubcommand::Test {