cksum: fix output bug and add test

xform/src/cksum.rs

@@ -48,10 +48,18 @@ fn cksum_file(filename: &str) -> io::Result<()> {
         crc = crc32::update(crc, &buffer[0..n_read]);
     }
 
+    let filename_prefix = {
+        if filename == "" {
+            ""
+        } else {
+            " "
+        }
+    };
     println!(
-        "{} {} {}",
+        "{} {}{}{}",
         crc32::finalize(crc, n_bytes as usize),
         n_bytes,
+        filename_prefix,
         filename
     );
 

xform/tests/integration.rs

@@ -0,0 +1,24 @@
+//
+// Copyright (c) 2024 Jeff Garzik
+//
+// This file is part of the posixutils-rs project covered under
+// the MIT License.  For the full license text, please see the LICENSE
+// file in the root directory of this project.
+// SPDX-License-Identifier: MIT
+//
+
+use plib::{run_test, TestPlan};
+
+fn cksum_test(test_data: &str, expected_output: &str) {
+    run_test(TestPlan {
+        cmd: String::from("cksum"),
+        args: Vec::new(),
+        stdin_data: String::from(test_data),
+        expected_out: String::from(expected_output),
+    });
+}
+
+#[test]
+fn test_cksum() {
+    cksum_test("foo\n", "3915528286 4\n");
+}