Add test for paste.

Makefile

@@ -164,6 +164,7 @@ TEST_PROGS  := \
   mkdir \
   mv \
   nl \
+  paste \
   seq \
   sort \
   test \

test/fixtures/paste/html_colors.expected

@@ -0,0 +1,16 @@
+white	#FFFFFF
+silver	#C0C0C0
+gray	#808080
+black	#000000
+red	#FF0000
+maroon	#800000
+yellow	#FFFF00
+olive	#808000
+lime	#00FF00
+green	#008000
+aqua	#00FFFF
+teal	#008080
+blue	#0000FF
+navy	#000080
+fuchsia	#FF00FF
+purple	#800080

test/fixtures/paste/html_colors.txt

@@ -0,0 +1,32 @@
+white
+#FFFFFF
+silver
+#C0C0C0
+gray
+#808080
+black
+#000000
+red
+#FF0000
+maroon
+#800000
+yellow
+#FFFF00
+olive
+#808000
+lime
+#00FF00
+green
+#008000
+aqua
+#00FFFF
+teal
+#008080
+blue
+#0000FF
+navy
+#000080
+fuchsia
+#FF00FF
+purple
+#800080

test/paste.rs

@@ -0,0 +1,27 @@
+use std::fs::File;
+use std::io::Read;
+use std::path::Path;
+use std::process::Command;
+
+static PROGNAME: &'static str = "./paste";
+
+#[test]
+fn test_combine_pairs_of_lines() {
+    let po = Command::new(PROGNAME)
+        .arg("-s")
+        .arg("-d")
+        .arg("\t\n")
+        .arg("html_colors.txt")
+        .output()
+        .unwrap_or_else(|err| panic!("{}", err));
+
+    let mut f = File::open(Path::new("html_colors.expected")).unwrap_or_else(|err| {
+        panic!("{}", err)
+    });
+    let mut expected = vec!();
+    match f.read_to_end(&mut expected) {
+        Ok(_) => {},
+        Err(err) => panic!("{}", err)
+    }
+    assert_eq!(String::from_utf8(po.stdout).unwrap(), String::from_utf8(expected).unwrap());
+}