Support creating missing directories with --output-file option

src/main.rs

@@ -217,6 +217,10 @@ pub fn main() -> Result<(), std::io::Error> {
       }
     }
 
+    let output_path = Path::new(output_file);
+    if let Some(p) = output_path.parent() {
+      fs::create_dir_all(p)?
+    };
     fs::write(output_file, code.as_bytes())?;
 
     if let Some(css_modules) = cli_args.css_modules {

tests/cli_integration_tests.rs

@@ -5,6 +5,7 @@ use indoc::indoc;
 use lightningcss::css_modules::CssModuleExport;
 use predicates::prelude::*;
 use std::collections::HashMap;
+use std::fs;
 use std::process::Command;
 
 fn test_file() -> Result<assert_fs::NamedTempFile, FixtureError> {
@@ -182,6 +183,28 @@ fn output_file_option() -> Result<(), Box<dyn std::error::Error>> {
   Ok(())
 }
 
+#[test]
+fn output_file_option_create_missing_directories() -> Result<(), Box<dyn std::error::Error>> {
+  let infile = test_file()?;
+  let outdir = assert_fs::TempDir::new()?;
+  let outfile = outdir.child("out.css");
+  outdir.close()?;
+  let mut cmd = Command::cargo_bin("lightningcss")?;
+  cmd.arg(infile.path());
+  cmd.arg("--output-file").arg(outfile.path());
+  cmd.assert().success();
+  outfile.assert(predicate::str::contains(indoc! {
+    r#"
+      .foo {
+        border: none;
+      }
+    "#
+  }));
+  fs::remove_dir_all(outfile.parent().unwrap())?;
+
+  Ok(())
+}
+
 #[test]
 fn minify_option() -> Result<(), Box<dyn std::error::Error>> {
   let infile = test_file()?;