mkfifo: general refactor, move to clap, add tests (#1945)

* mkfifo: general refactor, move to clap, add unimplemented flags

* chore: update Cargo.lock

* chore: delete unused variables, simplify multiple lines with crash

* test: add tests

* chore: revert the use of crash

* test: use even more invalid mod mode

tests/by-util/test_mkfifo.rs

@@ -1 +1,48 @@
-// ToDO: add tests
+use crate::common::util::*;
+
+#[test]
+fn test_create_fifo_missing_operand() {
+    new_ucmd!()
+        .fails()
+        .stderr_is("mkfifo: error: missing operand");
+}
+
+#[test]
+fn test_create_one_fifo() {
+    new_ucmd!().arg("abc").succeeds();
+}
+
+#[test]
+fn test_create_one_fifo_with_invalid_mode() {
+    new_ucmd!()
+        .arg("abcd")
+        .arg("-m")
+        .arg("invalid")
+        .fails()
+        .stderr
+        .contains("invalid mode");
+}
+
+#[test]
+fn test_create_multiple_fifos() {
+    new_ucmd!()
+        .arg("abcde")
+        .arg("def")
+        .arg("sed")
+        .arg("dum")
+        .succeeds();
+}
+
+#[test]
+fn test_create_one_fifo_with_mode() {
+    new_ucmd!().arg("abcde").arg("-m600").succeeds();
+}
+
+#[test]
+fn test_create_one_fifo_already_exists() {
+    new_ucmd!()
+        .arg("abcdef")
+        .arg("abcdef")
+        .fails()
+        .stderr_is("mkfifo: error: cannot create fifo 'abcdef': File exists");
+}