tests ~ reorganize tests

tests/by-util/test_unlink.rs

@@ -0,0 +1,51 @@
+use crate::common::util::*;
+
+#[test]
+fn test_unlink_file() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    let file = "test_unlink_file";
+
+    at.touch(file);
+
+    ucmd.arg(file).succeeds().no_stderr();
+
+    assert!(!at.file_exists(file));
+}
+
+#[test]
+fn test_unlink_multiple_files() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    let file_a = "test_unlink_multiple_file_a";
+    let file_b = "test_unlink_multiple_file_b";
+
+    at.touch(file_a);
+    at.touch(file_b);
+
+    ucmd.arg(file_a).arg(file_b).fails().stderr_is(
+        "unlink: error: extra operand: 'test_unlink_multiple_file_b'\nTry 'unlink --help' \
+                for more information.\n",
+    );
+}
+
+#[test]
+fn test_unlink_directory() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    let dir = "test_unlink_empty_directory";
+
+    at.mkdir(dir);
+
+    ucmd.arg(dir).fails().stderr_is(
+        "unlink: error: cannot unlink 'test_unlink_empty_directory': Not a regular file \
+                or symlink\n",
+    );
+}
+
+#[test]
+fn test_unlink_nonexistent() {
+    let file = "test_unlink_nonexistent";
+
+    new_ucmd!().arg(file).fails().stderr_is(
+        "unlink: error: Cannot stat 'test_unlink_nonexistent': No such file or directory \
+                (os error 2)\n",
+    );
+}