Add initial tests for head.

Makefile

@@ -170,6 +170,7 @@ TEST_PROGS  := \
   false \
   fold \
   hashsum \
+  head \
   mkdir \
   mv \
   nl \

test/fixtures/head/lorem_ipsum.txt

@@ -0,0 +1,24 @@
+Lorem ipsum dolor sit amet,
+consectetur adipiscing elit.
+Nunc interdum suscipit sem vel ornare.
+Proin euismod,
+justo sed mollis dictum,
+eros urna ultricies augue,
+eu pharetra mi ex id ante.
+Duis convallis porttitor aliquam.
+Nunc vitae tincidunt ex.
+Suspendisse iaculis ligula ac diam consectetur lacinia.
+Donec vel velit dui.
+Etiam fringilla,
+dolor quis tempor vehicula,
+lacus turpis bibendum velit,
+et pellentesque elit odio a magna.
+Cras vulputate tortor non libero vehicula euismod.
+Aliquam tincidunt nisl eget enim cursus,
+viverra sagittis magna commodo.
+Cras rhoncus egestas leo nec blandit.
+Suspendisse potenti.
+Etiam ullamcorper leo vel lacus vestibulum,
+cursus semper eros efficitur.
+In hac habitasse platea dictumst.
+Phasellus scelerisque vehicula fringilla.

test/fixtures/head/lorem_ipsum_1_line.expected

@@ -0,0 +1 @@
+Lorem ipsum dolor sit amet,

test/fixtures/head/lorem_ipsum_5_chars.expected

@@ -0,0 +1 @@
+Lorem

test/fixtures/head/lorem_ipsum_default.expected

@@ -0,0 +1,10 @@
+Lorem ipsum dolor sit amet,
+consectetur adipiscing elit.
+Nunc interdum suscipit sem vel ornare.
+Proin euismod,
+justo sed mollis dictum,
+eros urna ultricies augue,
+eu pharetra mi ex id ante.
+Duis convallis porttitor aliquam.
+Nunc vitae tincidunt ex.
+Suspendisse iaculis ligula ac diam consectetur lacinia.

test/head.rs

@@ -0,0 +1,65 @@
+use std::process::Command;
+use util::*;
+
+static PROGNAME: &'static str = "./head";
+static INPUT: &'static str = "lorem_ipsum.txt";
+
+#[path = "common/util.rs"]
+#[macro_use]
+mod util;
+
+#[test]
+fn test_stdin_default() {
+    let mut cmd = Command::new(PROGNAME);
+    let result = run_piped_stdin(&mut cmd, get_file_contents(INPUT));
+    assert_eq!(result.stdout, get_file_contents("lorem_ipsum_default.expected"));
+}
+
+#[test]
+fn test_stdin_1_line_obsolete() {
+    let mut cmd = Command::new(PROGNAME);
+    let result = run_piped_stdin(&mut cmd.args(&["-1"]), get_file_contents(INPUT));
+    assert_eq!(result.stdout, get_file_contents("lorem_ipsum_1_line.expected"));
+}
+
+#[test]
+fn test_stdin_1_line() {
+    let mut cmd = Command::new(PROGNAME);
+    let result = run_piped_stdin(&mut cmd.args(&["-n", "1"]), get_file_contents(INPUT));
+    assert_eq!(result.stdout, get_file_contents("lorem_ipsum_1_line.expected"));
+}
+
+#[test]
+fn test_stdin_5_chars() {
+    let mut cmd = Command::new(PROGNAME);
+    let result = run_piped_stdin(&mut cmd.args(&["-c", "5"]), get_file_contents(INPUT));
+    assert_eq!(result.stdout, get_file_contents("lorem_ipsum_5_chars.expected"));
+}
+
+#[test]
+fn test_single_default() {
+    let mut cmd = Command::new(PROGNAME);
+    let result = run(&mut cmd.arg(INPUT));
+    assert_eq!(result.stdout, get_file_contents("lorem_ipsum_default.expected"));
+}
+
+#[test]
+fn test_single_1_line_obsolete() {
+    let mut cmd = Command::new(PROGNAME);
+    let result = run(&mut cmd.args(&["-1", INPUT]));
+    assert_eq!(result.stdout, get_file_contents("lorem_ipsum_1_line.expected"));
+}
+
+#[test]
+fn test_single_1_line() {
+    let mut cmd = Command::new(PROGNAME);
+    let result = run(&mut cmd.args(&["-n", "1", INPUT]));
+    assert_eq!(result.stdout, get_file_contents("lorem_ipsum_1_line.expected"));
+}
+
+#[test]
+fn test_single_5_chars() {
+    let mut cmd = Command::new(PROGNAME);
+    let result = run(&mut cmd.args(&["-c", "5", INPUT]));
+    assert_eq!(result.stdout, get_file_contents("lorem_ipsum_5_chars.expected"));
+}