Add tests for unlink.

Makefile

@@ -182,6 +182,7 @@ TEST_PROGS  := \
   true \
   truncate \
   tsort \
+  unlink \
   unexpand
 
 TEST        ?= $(TEST_PROGS)

test/unlink.rs

@@ -0,0 +1,91 @@
+#![feature(path_ext)]
+#![allow(dead_code)]
+
+extern crate libc;
+
+use std::fs::{self, File, PathExt};
+use std::path::Path;
+use std::process::Command;
+use std::str::from_utf8;
+
+static PROGNAME: &'static str = "./unlink";
+
+macro_rules! assert_empty_stderr(
+    ($cond:expr) => (
+        if $cond.stderr.len() > 0 {
+            panic!(format!("stderr: {}", $cond.stderr))
+        }
+    );
+);
+
+struct CmdResult {
+    success: bool,
+    stderr: String,
+    stdout: String,
+}
+
+fn run(cmd: &mut Command) -> CmdResult {
+    let prog = cmd.output().unwrap();
+    CmdResult {
+        success: prog.status.success(),
+        stderr: from_utf8(&prog.stderr).unwrap().to_string(),
+        stdout: from_utf8(&prog.stdout).unwrap().to_string(),
+    }
+}
+
+fn mkdir(dir: &str) {
+    fs::create_dir(dir).unwrap();
+}
+
+fn touch(file: &str) {
+    File::create(file).unwrap();
+}
+
+#[test]
+fn test_unlink_file() {
+    let file = "test_unlink_file";
+
+    touch(file);
+
+    let result = run(Command::new(PROGNAME).arg(file));
+    assert_empty_stderr!(result);
+    assert!(result.success);
+
+    assert!(!Path::new(file).exists());
+}
+
+#[test]
+fn test_unlink_multiple_files() {
+    let file_a = "test_unlink_multiple_file_a";
+    let file_b = "test_unlink_multiple_file_b";
+
+    touch(file_a);
+    touch(file_b);
+
+    let result = run(Command::new(PROGNAME).arg(file_a).arg(file_b));
+    assert_eq!(result.stderr,
+        "unlink: error: extra operand: 'test_unlink_multiple_file_b'\nTry './unlink --help' for more information.\n");
+    assert!(!result.success);
+}
+
+#[test]
+fn test_unlink_directory() {
+    let dir = "test_unlink_empty_directory";
+
+    mkdir(dir);
+
+    let result = run(Command::new(PROGNAME).arg(dir));
+    assert_eq!(result.stderr,
+        "unlink: error: cannot unlink 'test_unlink_empty_directory': Not a regular file or symlink\n");
+    assert!(!result.success);
+}
+
+#[test]
+fn test_unlink_nonexistent() {
+    let file = "test_unlink_nonexistent";
+
+    let result = run(Command::new(PROGNAME).arg(file));
+    assert_eq!(result.stderr,
+        "unlink: error: Cannot stat 'test_unlink_nonexistent': No such file or directory (os error 2)\n");
+    assert!(!result.success);
+}