implement many copy flags

- Refactored towards extensibility

tests/fixtures/cp/existing_file.txt

@@ -0,0 +1 @@
+Cogito ergo sum.

tests/fixtures/cp/how_are_you.txt

@@ -0,0 +1 @@
+How are you?

tests/test_cp.rs

@@ -1,11 +1,15 @@
 use common::util::*;
+use std::fs::set_permissions;
 
-static TEST_HELLO_WORLD_SOURCE: &'static str = "hello_world.txt";
-static TEST_HELLO_WORLD_DEST: &'static str = "copy_of_hello_world.txt";
-static TEST_COPY_TO_FOLDER: &'static str = "hello_dir/";
-static TEST_COPY_TO_FOLDER_FILE: &'static str = "hello_dir/hello_world.txt";
-static TEST_COPY_FROM_FOLDER: &'static str = "hello_dir_with_file/";
-static TEST_COPY_FROM_FOLDER_FILE: &'static str = "hello_dir_with_file/hello_world.txt";
+static TEST_EXISTING_FILE:         &str = "existing_file.txt";
+static TEST_HELLO_WORLD_SOURCE:    &str = "hello_world.txt";
+static TEST_HELLO_WORLD_DEST:      &str = "copy_of_hello_world.txt";
+static TEST_HOW_ARE_YOU_SOURCE:    &str = "how_are_you.txt";
+static TEST_HOW_ARE_YOU_DEST:      &str = "hello_dir/how_are_you.txt";
+static TEST_COPY_TO_FOLDER:        &str = "hello_dir/";
+static TEST_COPY_TO_FOLDER_FILE:   &str = "hello_dir/hello_world.txt";
+static TEST_COPY_FROM_FOLDER:      &str = "hello_dir_with_file/";
+static TEST_COPY_FROM_FOLDER_FILE: &str = "hello_dir_with_file/hello_world.txt";
 
 #[test]
 fn test_cp_cp() {
@@ -23,6 +27,58 @@ fn test_cp_cp() {
     assert_eq!(at.read(TEST_HELLO_WORLD_DEST), "Hello, World!\n");
 }
 
+
+#[test]
+fn test_cp_duplicate_files() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    let result = ucmd.arg(TEST_HELLO_WORLD_SOURCE)
+        .arg(TEST_HELLO_WORLD_SOURCE)
+        .arg(TEST_COPY_TO_FOLDER)
+        .run();
+
+    assert!(result.success);
+    assert!(result.stderr.contains("specified more than once"));
+    assert_eq!(at.read(TEST_COPY_TO_FOLDER_FILE), "Hello, World!\n");
+}
+
+
+#[test]
+fn test_cp_multiple_files_target_is_file() {
+    let (_, mut ucmd) = at_and_ucmd!();
+    let result = ucmd.arg(TEST_HELLO_WORLD_SOURCE)
+        .arg(TEST_HELLO_WORLD_SOURCE)
+        .arg(TEST_EXISTING_FILE)
+        .run();
+
+    assert!(!result.success);
+    assert!(result.stderr.contains("not a directory"));
+}
+
+#[test]
+fn test_cp_directory_not_recursive() {
+    let (_, mut ucmd) = at_and_ucmd!();
+    let result = ucmd.arg(TEST_COPY_TO_FOLDER)
+        .arg(TEST_HELLO_WORLD_DEST)
+        .run();
+
+    assert!(!result.success);
+    assert!(result.stderr.contains("omitting directory"));
+}
+
+
+#[test]
+fn test_cp_multiple_files() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    let result = ucmd.arg(TEST_HELLO_WORLD_SOURCE)
+        .arg(TEST_HOW_ARE_YOU_SOURCE)
+        .arg(TEST_COPY_TO_FOLDER)
+        .run();
+
+    assert!(result.success);
+    assert_eq!(at.read(TEST_COPY_TO_FOLDER_FILE), "Hello, World!\n");
+    assert_eq!(at.read(TEST_HOW_ARE_YOU_DEST), "How are you?\n");
+}
+
 #[test]
 fn test_cp_recurse() {
     //let (at, mut ucmd) = at_and_ucmd!();
@@ -82,3 +138,156 @@ fn test_cp_with_dirs() {
     assert!(result_from_dir.success);
     assert_eq!(at.read(TEST_HELLO_WORLD_DEST), "Hello, World!\n");
 }
+
+#[test]
+fn test_cp_arg_target_directory() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    let result = ucmd.arg(TEST_HELLO_WORLD_SOURCE)
+        .arg("-t")
+        .arg(TEST_COPY_TO_FOLDER)
+        .run();
+
+    assert!(result.success);
+    assert_eq!(at.read(TEST_COPY_TO_FOLDER_FILE), "Hello, World!\n");
+}
+
+#[test]
+fn test_cp_arg_no_target_directory() {
+    let (_, mut ucmd) = at_and_ucmd!();
+    let result = ucmd.arg(TEST_HELLO_WORLD_SOURCE)
+        .arg("-v")
+        .arg("-T")
+        .arg(TEST_COPY_TO_FOLDER)
+        .run();
+
+    assert!(!result.success);
+    assert!(result.stderr.contains("cannot overwrite directory"));
+}
+
+#[test]
+fn test_cp_arg_interactive() {
+    let (_, mut ucmd) = at_and_ucmd!();
+    let result = ucmd.arg(TEST_HELLO_WORLD_SOURCE)
+        .arg(TEST_HOW_ARE_YOU_SOURCE)
+        .arg("-i")
+        .pipe_in("N\n")
+        .run();
+
+    assert!(result.success);
+    assert!(result.stderr.contains("Not overwriting"));
+}
+
+#[test]
+#[cfg(target_os="unix")]
+fn test_cp_arg_link() {
+    use std::os::linux::fs::MetadataExt;
+
+    let (at, mut ucmd) = at_and_ucmd!();
+    let result = ucmd.arg(TEST_HELLO_WORLD_SOURCE)
+        .arg("--link")
+        .arg(TEST_HELLO_WORLD_DEST)
+        .run();
+
+    assert!(result.success);
+    assert_eq!(at.metadata(TEST_HELLO_WORLD_SOURCE).st_nlink(), 2);
+}
+
+#[test]
+fn test_cp_arg_symlink() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    let result = ucmd.arg(TEST_HELLO_WORLD_SOURCE)
+        .arg("--symbolic-link")
+        .arg(TEST_HELLO_WORLD_DEST)
+        .run();
+
+    assert!(result.success);
+    assert!(at.is_symlink(TEST_HELLO_WORLD_DEST));
+}
+
+
+#[test]
+fn test_cp_arg_no_clobber() {
+    let (at, mut ucmd) = at_and_ucmd!();
+    let result = ucmd.arg(TEST_HELLO_WORLD_SOURCE)
+        .arg("--no-clobber")
+        .arg(TEST_HOW_ARE_YOU_SOURCE)
+        .run();
+
+    assert!(result.success);
+    assert_eq!(at.read(TEST_HOW_ARE_YOU_SOURCE), "How are you?\n");
+    assert!(result.stderr.contains("Not overwriting"));
+}
+
+#[test]
+#[cfg(not(windows))]
+fn test_cp_arg_force() {
+    let (at, mut ucmd) = at_and_ucmd!();
+
+    // create dest without write permissions
+    let mut permissions = at.make_file(TEST_HELLO_WORLD_DEST).metadata().unwrap().permissions();
+    permissions.set_readonly(true);
+    set_permissions(at.plus(TEST_HELLO_WORLD_DEST), permissions).unwrap();
+
+    let result = ucmd.arg(TEST_HELLO_WORLD_SOURCE)
+        .arg("--force")
+        .arg(TEST_HELLO_WORLD_DEST)
+        .run();
+
+    println!("{:?}", result.stderr);
+    println!("{:?}", result.stdout);
+
+    assert!(result.success);
+    assert_eq!(at.read(TEST_HELLO_WORLD_DEST), "Hello, World!\n");
+}
+
+/// TODO: write a better test that differentiates --remove-destination
+/// from --force. Also this test currently doesn't work on
+/// Windows. This test originally checked file timestamps, which
+/// proved to be unreliable per target / CI platform
+#[test]
+#[cfg(not(windows))]
+fn test_cp_arg_remove_destination() {
+    let (at, mut ucmd) = at_and_ucmd!();
+
+    // create dest without write permissions
+    let mut permissions = at.make_file(TEST_HELLO_WORLD_DEST).metadata().unwrap().permissions();
+    permissions.set_readonly(true);
+    set_permissions(at.plus(TEST_HELLO_WORLD_DEST), permissions).unwrap();
+
+    let result = ucmd.arg(TEST_HELLO_WORLD_SOURCE)
+        .arg("--remove-destination")
+        .arg(TEST_HELLO_WORLD_DEST)
+        .run();
+
+    assert!(result.success);
+    assert_eq!(at.read(TEST_HELLO_WORLD_DEST), "Hello, World!\n");
+}
+
+#[test]
+fn test_cp_arg_backup() {
+    let (at, mut ucmd) = at_and_ucmd!();
+
+    let result = ucmd.arg(TEST_HELLO_WORLD_SOURCE)
+        .arg("--backup")
+        .arg(TEST_HOW_ARE_YOU_SOURCE)
+        .run();
+
+    assert!(result.success);
+    assert_eq!(at.read(TEST_HOW_ARE_YOU_SOURCE), "Hello, World!\n");
+    assert_eq!(at.read(&*format!("{}~", TEST_HOW_ARE_YOU_SOURCE)), "How are you?\n");
+}
+
+#[test]
+fn test_cp_arg_suffix() {
+    let (at, mut ucmd) = at_and_ucmd!();
+
+    let result = ucmd.arg(TEST_HELLO_WORLD_SOURCE)
+        .arg("--suffix")
+        .arg(".bak")
+        .arg(TEST_HOW_ARE_YOU_SOURCE)
+        .run();
+
+    assert!(result.success);
+    assert_eq!(at.read(TEST_HOW_ARE_YOU_SOURCE), "Hello, World!\n");
+    assert_eq!(at.read(&*format!("{}.bak", TEST_HOW_ARE_YOU_SOURCE)), "How are you?\n");
+}