tests ~ reorganize tests

tests/by-util/test_tac.rs

@@ -0,0 +1,51 @@
+use crate::common::util::*;
+
+#[test]
+fn test_stdin_default() {
+    new_ucmd!()
+        .pipe_in("100\n200\n300\n400\n500")
+        .run()
+        .stdout_is("500400\n300\n200\n100\n");
+}
+
+#[test]
+fn test_stdin_non_newline_separator() {
+    new_ucmd!()
+        .args(&["-s", ":"])
+        .pipe_in("100:200:300:400:500")
+        .run()
+        .stdout_is("500400:300:200:100:");
+}
+
+#[test]
+fn test_stdin_non_newline_separator_before() {
+    new_ucmd!()
+        .args(&["-b", "-s", ":"])
+        .pipe_in("100:200:300:400:500")
+        .run()
+        .stdout_is("500:400:300:200:100");
+}
+
+#[test]
+fn test_single_default() {
+    new_ucmd!()
+        .arg("prime_per_line.txt")
+        .run()
+        .stdout_is_fixture("prime_per_line.expected");
+}
+
+#[test]
+fn test_single_non_newline_separator() {
+    new_ucmd!()
+        .args(&["-s", ":", "delimited_primes.txt"])
+        .run()
+        .stdout_is_fixture("delimited_primes.expected");
+}
+
+#[test]
+fn test_single_non_newline_separator_before() {
+    new_ucmd!()
+        .args(&["-b", "-s", ":", "delimited_primes.txt"])
+        .run()
+        .stdout_is_fixture("delimited_primes_before.expected");
+}