numfmt: implement --field

tests/by-util/test_numfmt.rs

@@ -315,3 +315,71 @@ fn test_to_iec_i_should_truncate_output() {
         .succeeds()
         .stdout_is_fixture("gnutest_iec-i_result.txt");
 }
+
+#[test]
+fn test_format_selected_field() {
+    new_ucmd!()
+        .args(&["--from=auto", "--field", "3", "1K 2K 3K"])
+        .succeeds()
+        .stdout_only("1K 2K 3000\n");
+    new_ucmd!()
+        .args(&["--from=auto", "--field", "2", "1K 2K 3K"])
+        .succeeds()
+        .stdout_only("1K 2000 3K\n");
+}
+
+#[test]
+fn test_format_selected_fields() {
+    new_ucmd!()
+        .args(&["--from=auto", "--field", "1,4,3", "1K 2K 3K 4K 5K 6K"])
+        .succeeds()
+        .stdout_only("1000 2K 3000 4000 5K 6K\n");
+}
+
+#[test]
+fn test_should_succeed_if_selected_field_out_of_range() {
+    new_ucmd!()
+        .args(&["--from=auto", "--field", "9", "1K 2K 3K"])
+        .succeeds()
+        .stdout_only("1K 2K 3K\n");
+}
+
+#[test]
+fn test_format_selected_field_range() {
+    new_ucmd!()
+        .args(&["--from=auto", "--field", "2-5", "1K 2K 3K 4K 5K 6K"])
+        .succeeds()
+        .stdout_only("1K 2000 3000 4000 5000 6K\n");
+}
+
+#[test]
+fn test_should_succeed_if_range_out_of_bounds() {
+    new_ucmd!()
+        .args(&["--from=auto", "--field", "5-10", "1K 2K 3K 4K 5K 6K"])
+        .succeeds()
+        .stdout_only("1K 2K 3K 4K 5000 6000\n");
+}
+
+#[test]
+fn test_implied_initial_field_value() {
+    new_ucmd!()
+        .args(&["--from=auto", "--field", "-2", "1K 2K 3K"])
+        .succeeds()
+        .stdout_only("1000 2000 3K\n");
+
+    // same as above but with the equal sign
+    new_ucmd!()
+        .args(&["--from=auto", "--field=-2", "1K 2K 3K"])
+        .succeeds()
+        .stdout_only("1000 2000 3K\n");
+}
+
+#[test]
+fn test_field_df_example() {
+    // df -B1 | numfmt --header --field 2-4 --to=si
+    new_ucmd!()
+        .args(&["--header", "--field", "2-4", "--to=si"])
+        .pipe_in_fixture("df_input.txt")
+        .succeeds()
+        .stdout_is_fixture("df_expected.txt");
+}

tests/fixtures/numfmt/df_expected.txt

@@ -0,0 +1,8 @@
+Filesystem                1B-blocks         Used    Available Use% Mounted on
+udev                           8.2G            0         8.2G   0% /dev
+tmpfs                          1.7G         2.1M         1.7G   1% /run
+/dev/nvme0n1p2                 1.1T         433G         523G  46% /
+tmpfs                          8.3G         145M         8.1G   2% /dev/shm
+tmpfs                          5.3M         4.1K         5.3M   1% /run/lock
+tmpfs                          8.3G            0         8.3G   0% /sys/fs/cgroup
+/dev/nvme0n1p1                 536M         8.2M         528M   2% /boot/efi

tests/fixtures/numfmt/df_input.txt

@@ -0,0 +1,8 @@
+Filesystem                1B-blocks         Used    Available Use% Mounted on
+udev                     8192688128            0   8192688128   0% /dev
+tmpfs                    1643331584      2015232   1641316352   1% /run
+/dev/nvme0n1p2        1006530654208 432716689408 522613624832  46% /
+tmpfs                    8216649728    144437248   8072212480   2% /dev/shm
+tmpfs                       5242880         4096      5238784   1% /run/lock
+tmpfs                    8216649728            0   8216649728   0% /sys/fs/cgroup
+/dev/nvme0n1p1            535805952      8175616    527630336   2% /boot/efi