clean cp tests (#12202)

# Description
There are lots of duplicate test for `cp`, it's because we once have
`old-cp` command.

Today `old-cp` is removed, so there is no need to keep these tests.

crates/nu-command/tests/commands/ucp.rs

@@ -1173,3 +1173,52 @@ fn test_cp_to_customized_home_directory() {
         ));
     })
 }
+
+#[test]
+fn copy_file_with_update_flag() {
+    copy_file_with_update_flag_impl(false);
+    copy_file_with_update_flag_impl(true);
+}
+
+fn copy_file_with_update_flag_impl(progress: bool) {
+    Playground::setup("cp_test_36", |_dirs, sandbox| {
+        sandbox.with_files(vec![
+            EmptyFile("valid.txt"),
+            FileWithContent("newer_valid.txt", "body"),
+        ]);
+
+        let progress_flag = if progress { "-p" } else { "" };
+
+        let actual = nu!(
+            cwd: sandbox.cwd(),
+            "cp {} -u valid.txt newer_valid.txt; open newer_valid.txt",
+            progress_flag,
+        );
+        assert!(actual.out.contains("body"));
+
+        // create a file after assert to make sure that newest_valid.txt is newest
+        std::thread::sleep(std::time::Duration::from_secs(1));
+        sandbox.with_files(vec![FileWithContent("newest_valid.txt", "newest_body")]);
+        let actual = nu!(cwd: sandbox.cwd(), "cp {} -u newest_valid.txt valid.txt; open valid.txt", progress_flag);
+        assert_eq!(actual.out, "newest_body");
+
+        // when destination doesn't exist
+        let actual = nu!(cwd: sandbox.cwd(), "cp {} -u newest_valid.txt des_missing.txt; open des_missing.txt", progress_flag);
+        assert_eq!(actual.out, "newest_body");
+    });
+}
+
+#[test]
+fn cp_with_cd() {
+    Playground::setup("cp_test_37", |_dirs, sandbox| {
+        sandbox
+            .mkdir("tmp_dir")
+            .with_files(vec![FileWithContent("tmp_dir/file.txt", "body")]);
+
+        let actual = nu!(
+            cwd: sandbox.cwd(),
+            r#"do { cd tmp_dir; let f = 'file.txt'; cp $f .. }; open file.txt"#,
+        );
+        assert!(actual.out.contains("body"));
+    });
+}