refactor(cli/flags): use an optional non zero usize for fail-fast (#11804)

Changes the type of the `fail_fast` flag from `Option<usize>` to
`Option<NonZeroUsize>` as an optional value of zero isn't sound.

cli/flags.rs

@@ -101,7 +101,7 @@ pub enum DenoSubcommand {
   Test {
     doc: bool,
     no_run: bool,
-    fail_fast: Option<usize>,
+    fail_fast: Option<NonZeroUsize>,
     quiet: bool,
     allow_none: bool,
     include: Option<Vec<String>>,
@@ -1047,16 +1047,9 @@ fn test_subcommand<'a, 'b>() -> App<'a, 'b> {
         .takes_value(true)
         .require_equals(true)
         .value_name("N")
-        .validator(|val: String| match val.parse::<usize>() {
-          Ok(val) => {
-            if val == 0 {
-              return Err(
-                "fail-fast should be an number greater than 0".to_string(),
-              );
-            }
-            Ok(())
-          }
-          Err(_) => Err("fail-fast should be a number".to_string()),
+        .validator(|val: String| match val.parse::<NonZeroUsize>() {
+          Ok(_) => Ok(()),
+          Err(_) => Err("fail-fast should be a non zero integer".to_string()),
         }),
     )
     .arg(
@@ -1786,7 +1779,7 @@ fn test_parse(flags: &mut Flags, matches: &clap::ArgMatches) {
     if let Some(value) = matches.value_of("fail-fast") {
       Some(value.parse().unwrap())
     } else {
-      Some(1)
+      Some(NonZeroUsize::new(1).unwrap())
     }
   } else {
     None
@@ -3663,7 +3656,7 @@ mod tests {
         subcommand: DenoSubcommand::Test {
           no_run: false,
           doc: false,
-          fail_fast: Some(3),
+          fail_fast: Some(NonZeroUsize::new(3).unwrap()),
           filter: None,
           allow_none: false,
           quiet: false,
@@ -3674,6 +3667,9 @@ mod tests {
         ..Flags::default()
       }
     );
+
+    let r = flags_from_vec(svec!["deno", "test", "--fail-fast=0"]);
+    assert!(r.is_err());
   }
 
   #[test]

cli/main.rs

@@ -77,6 +77,7 @@ use std::env;
 use std::io::Read;
 use std::io::Write;
 use std::iter::once;
+use std::num::NonZeroUsize;
 use std::path::PathBuf;
 use std::pin::Pin;
 use std::rc::Rc;
@@ -1004,7 +1005,7 @@ async fn test_command(
   include: Option<Vec<String>>,
   no_run: bool,
   doc: bool,
-  fail_fast: Option<usize>,
+  fail_fast: Option<NonZeroUsize>,
   quiet: bool,
   allow_none: bool,
   filter: Option<String>,

cli/tools/test_runner.rs

@@ -469,7 +469,7 @@ pub async fn run_tests(
   doc_modules: Vec<ModuleSpecifier>,
   test_modules: Vec<ModuleSpecifier>,
   no_run: bool,
-  fail_fast: Option<usize>,
+  fail_fast: Option<NonZeroUsize>,
   quiet: bool,
   allow_none: bool,
   filter: Option<String>,
@@ -621,7 +621,7 @@ pub async fn run_tests(
         }
 
         if let Some(x) = fail_fast {
-          if summary.failed >= x {
+          if summary.failed >= x.get() {
             break;
           }
         }