df: fix incorrect whitespace between columns

Fixes #3194

src/uu/df/src/columns.rs

@@ -183,4 +183,31 @@ impl Column {
             _ => Err(()),
         }
     }
+
+    /// Return the alignment of the specified column.
+    pub(crate) fn alignment(column: &Self) -> Alignment {
+        match column {
+            Self::Source | Self::Target | Self::File | Self::Fstype => Alignment::Left,
+            _ => Alignment::Right,
+        }
+    }
+
+    /// Return the minimum width of the specified column.
+    pub(crate) fn min_width(column: &Self) -> usize {
+        match column {
+            // 14 = length of "Filesystem" plus 4 spaces
+            Self::Source => 14,
+            // the shortest headers have a length of 4 chars so we use that as the minimum width
+            _ => 4,
+        }
+    }
+}
+
+/// A column's alignment.
+///
+/// We define our own `Alignment` enum instead of using `std::fmt::Alignment` because df doesn't
+/// have centered columns and hence a `Center` variant is not needed.
+pub(crate) enum Alignment {
+    Left,
+    Right,
 }

src/uu/df/src/df.rs

@@ -25,7 +25,7 @@ use std::path::Path;
 use crate::blocks::{block_size_from_matches, BlockSize};
 use crate::columns::{Column, ColumnError};
 use crate::filesystem::Filesystem;
-use crate::table::{DisplayRow, Header, Row};
+use crate::table::Table;
 
 static ABOUT: &str = "Show information about the file system on which each FILE resides,\n\
                       or all file systems by default.";
@@ -380,26 +380,13 @@ pub fn uumain(args: impl uucore::Args) -> UResult<()> {
         }
     };
 
-    // The running total of filesystem sizes and usage.
-    //
-    // This accumulator is computed in case we need to display the
-    // total counts in the last row of the table.
-    let mut total = Row::new("total");
+    // This can happen if paths are given as command-line arguments
+    // but none of the paths exist.
+    if filesystems.is_empty() {
+        return Ok(());
+    }
 
-    println!("{}", Header::new(&opt));
-    for filesystem in filesystems {
-        // If the filesystem is not empty, or if the options require
-        // showing all filesystems, then print the data as a row in
-        // the output table.
-        if opt.show_all_fs || filesystem.usage.blocks > 0 {
-            let row = Row::from(filesystem);
-            println!("{}", DisplayRow::new(&row, &opt));
-            total += row;
-        }
-    }
-    if opt.show_total {
-        println!("{}", DisplayRow::new(&total, &opt));
-    }
+    println!("{}", Table::new(&opt, filesystems));
 
     Ok(())
 }

tests/by-util/test_df.rs

@@ -29,9 +29,26 @@ fn test_df_compatible_si() {
 #[test]
 fn test_df_output() {
     let expected = if cfg!(target_os = "macos") {
-        "Filesystem               Size         Used    Available     Capacity  Use% Mounted on       "
+        vec![
+            "Filesystem",
+            "Size",
+            "Used",
+            "Available",
+            "Capacity",
+            "Use%",
+            "Mounted",
+            "on",
+        ]
     } else {
-        "Filesystem               Size         Used    Available  Use% Mounted on       "
+        vec![
+            "Filesystem",
+            "Size",
+            "Used",
+            "Available",
+            "Use%",
+            "Mounted",
+            "on",
+        ]
     };
     let output = new_ucmd!()
         .arg("-H")
@@ -39,6 +56,7 @@ fn test_df_output() {
         .succeeds()
         .stdout_move_str();
     let actual = output.lines().take(1).collect::<Vec<&str>>()[0];
+    let actual = actual.split_whitespace().collect::<Vec<_>>();
     assert_eq!(actual, expected);
 }
 
@@ -253,23 +271,26 @@ fn test_block_size_1024() {
     assert_eq!(get_header(34 * 1024 * 1024 * 1024), "34G-blocks");
 }
 
-// TODO The spacing does not match GNU df. Also we need to remove
-// trailing spaces from the heading row.
 #[test]
 fn test_output_selects_columns() {
     let output = new_ucmd!()
         .args(&["--output=source"])
         .succeeds()
         .stdout_move_str();
-    assert_eq!(output.lines().next().unwrap(), "Filesystem       ");
+    assert_eq!(output.lines().next().unwrap().trim_end(), "Filesystem");
 
     let output = new_ucmd!()
         .args(&["--output=source,target"])
         .succeeds()
         .stdout_move_str();
     assert_eq!(
-        output.lines().next().unwrap(),
-        "Filesystem       Mounted on       "
+        output
+            .lines()
+            .next()
+            .unwrap()
+            .split_whitespace()
+            .collect::<Vec<_>>(),
+        vec!["Filesystem", "Mounted", "on"]
     );
 
     let output = new_ucmd!()
@@ -277,8 +298,13 @@ fn test_output_selects_columns() {
         .succeeds()
         .stdout_move_str();
     assert_eq!(
-        output.lines().next().unwrap(),
-        "Filesystem       Mounted on               Used "
+        output
+            .lines()
+            .next()
+            .unwrap()
+            .split_whitespace()
+            .collect::<Vec<_>>(),
+        vec!["Filesystem", "Mounted", "on", "Used"]
     );
 }
 
@@ -289,12 +315,16 @@ fn test_output_multiple_occurrences() {
         .succeeds()
         .stdout_move_str();
     assert_eq!(
-        output.lines().next().unwrap(),
-        "Filesystem       Mounted on       "
+        output
+            .lines()
+            .next()
+            .unwrap()
+            .split_whitespace()
+            .collect::<Vec<_>>(),
+        vec!["Filesystem", "Mounted", "on"]
     );
 }
 
-// TODO Fix the spacing.
 #[test]
 fn test_output_file_all_filesystems() {
     // When run with no positional arguments, `df` lets "-" represent
@@ -304,13 +334,12 @@ fn test_output_file_all_filesystems() {
         .succeeds()
         .stdout_move_str();
     let mut lines = output.lines();
-    assert_eq!(lines.next().unwrap(), "File            ");
+    assert_eq!(lines.next().unwrap(), "File");
     for line in lines {
-        assert_eq!(line, "-               ");
+        assert_eq!(line, "-   ");
     }
 }
 
-// TODO Fix the spacing.
 #[test]
 fn test_output_file_specific_files() {
     // Create three files.
@@ -326,15 +355,7 @@ fn test_output_file_specific_files() {
         .succeeds()
         .stdout_move_str();
     let actual: Vec<&str> = output.lines().collect();
-    assert_eq!(
-        actual,
-        vec![
-            "File            ",
-            "a               ",
-            "b               ",
-            "c               "
-        ]
-    );
+    assert_eq!(actual, vec!["File", "a   ", "b   ", "c   "]);
 }
 
 #[test]
@@ -355,5 +376,5 @@ fn test_nonexistent_file() {
         .args(&["--output=file", "does-not-exist", "."])
         .fails()
         .stderr_is("df: does-not-exist: No such file or directory\n")
-        .stdout_is("File            \n.               \n");
+        .stdout_is("File\n.   \n");
 }