fmt: `deno fmt -` formats stdin and print to stdout (#3920)

1 files changed, 16 insertions, 1 deletions

diff --git a/cli/flags.rs b/cli/flags.rs
index 748a7f95e..a8c51093e 100644
--- a/cli/flags.rs
+++ b/cli/flags.rs
@@ -550,7 +550,10 @@ fn fmt_subcommand<'a, 'b>() -> App<'a, 'b> {
 
   deno fmt myfile1.ts myfile2.ts
 
-  deno fmt --check",
+  deno fmt --check
+
+  # Format stdin and write to stdout
+  cat file.ts | deno fmt -",
     )
     .arg(
       Arg::with_name("check")
@@ -1390,6 +1393,18 @@ mod tests {
         ..DenoFlags::default()
       }
     );
+
+    let r = flags_from_vec_safe(svec!["deno", "fmt"]);
+    assert_eq!(
+      r.unwrap(),
+      DenoFlags {
+        subcommand: DenoSubcommand::Format {
+          check: false,
+          files: None
+        },
+        ..DenoFlags::default()
+      }
+    );
   }
 
   #[test]