Fix some tests to not use CmdResult fields

tests/by-util/test_du.rs

@@ -7,10 +7,9 @@ const SUB_LINK: &str = "subdir/links/sublink.txt";
 
 #[test]
 fn test_du_basics() {
-    let (_at, mut ucmd) = at_and_ucmd!();
-    let result = ucmd.run();
-    assert!(result.success);
-    assert_eq!(result.stderr, "");
+    new_ucmd!()
+        .succeeds()
+        .no_stderr();
 }
 #[cfg(target_vendor = "apple")]
 fn _du_basics(s: String) {
@@ -22,7 +21,7 @@ fn _du_basics(s: String) {
     assert_eq!(s, answer);
 }
 #[cfg(not(target_vendor = "apple"))]
-fn _du_basics(s: String) {
+fn _du_basics(s: &str) {
     let answer = "28\t./subdir
 8\t./subdir/deeper
 16\t./subdir/links
@@ -38,19 +37,19 @@ fn test_du_basics_subdir() {
     let result = ucmd.arg(SUB_DIR).run();
     assert!(result.success);
     assert_eq!(result.stderr, "");
-    _du_basics_subdir(result.stdout);
+    _du_basics_subdir(result.stdout_str());
 }
 
 #[cfg(target_vendor = "apple")]
-fn _du_basics_subdir(s: String) {
+fn _du_basics_subdir(s: &str) {
     assert_eq!(s, "4\tsubdir/deeper\n");
 }
 #[cfg(target_os = "windows")]
-fn _du_basics_subdir(s: String) {
+fn _du_basics_subdir(s: &str) {
     assert_eq!(s, "0\tsubdir/deeper\n");
 }
 #[cfg(all(not(target_vendor = "apple"), not(target_os = "windows")))]
-fn _du_basics_subdir(s: String) {
+fn _du_basics_subdir(s: &str) {
     // MS-WSL linux has altered expected output
     if !is_wsl() {
         assert_eq!(s, "8\tsubdir/deeper\n");
@@ -64,7 +63,7 @@ fn test_du_basics_bad_name() {
     let (_at, mut ucmd) = at_and_ucmd!();
 
     let result = ucmd.arg("bad_name").run();
-    assert_eq!(result.stdout, "");
+    assert_eq!(result.stdout_str(), "");
     assert_eq!(
         result.stderr,
         "du: error: bad_name: No such file or directory\n"
@@ -81,20 +80,20 @@ fn test_du_soft_link() {
     let result = ts.ucmd().arg(SUB_DIR_LINKS).run();
     assert!(result.success);
     assert_eq!(result.stderr, "");
-    _du_soft_link(result.stdout);
+    _du_soft_link(result.stdout_str());
 }
 
 #[cfg(target_vendor = "apple")]
-fn _du_soft_link(s: String) {
+fn _du_soft_link(s: &str) {
     // 'macos' host variants may have `du` output variation for soft links
     assert!((s == "12\tsubdir/links\n") || (s == "16\tsubdir/links\n"));
 }
 #[cfg(target_os = "windows")]
-fn _du_soft_link(s: String) {
+fn _du_soft_link(s: &str) {
     assert_eq!(s, "8\tsubdir/links\n");
 }
 #[cfg(all(not(target_vendor = "apple"), not(target_os = "windows")))]
-fn _du_soft_link(s: String) {
+fn _du_soft_link(s: &str) {
     // MS-WSL linux has altered expected output
     if !is_wsl() {
         assert_eq!(s, "16\tsubdir/links\n");
@@ -114,19 +113,19 @@ fn test_du_hard_link() {
     assert!(result.success);
     assert_eq!(result.stderr, "");
     // We do not double count hard links as the inodes are identical
-    _du_hard_link(result.stdout);
+    _du_hard_link(result.stdout_str());
 }
 
 #[cfg(target_vendor = "apple")]
-fn _du_hard_link(s: String) {
+fn _du_hard_link(s: &str) {
     assert_eq!(s, "12\tsubdir/links\n")
 }
 #[cfg(target_os = "windows")]
-fn _du_hard_link(s: String) {
+fn _du_hard_link(s: &str) {
     assert_eq!(s, "8\tsubdir/links\n")
 }
 #[cfg(all(not(target_vendor = "apple"), not(target_os = "windows")))]
-fn _du_hard_link(s: String) {
+fn _du_hard_link(s: &str) {
     // MS-WSL linux has altered expected output
     if !is_wsl() {
         assert_eq!(s, "16\tsubdir/links\n");
@@ -142,19 +141,19 @@ fn test_du_d_flag() {
     let result = ts.ucmd().arg("-d").arg("1").run();
     assert!(result.success);
     assert_eq!(result.stderr, "");
-    _du_d_flag(result.stdout);
+    _du_d_flag(result.stdout_str());
 }
 
 #[cfg(target_vendor = "apple")]
-fn _du_d_flag(s: String) {
+fn _du_d_flag(s: &str) {
     assert_eq!(s, "16\t./subdir\n20\t./\n");
 }
 #[cfg(target_os = "windows")]
-fn _du_d_flag(s: String) {
+fn _du_d_flag(s: &str) {
     assert_eq!(s, "8\t./subdir\n8\t./\n");
 }
 #[cfg(all(not(target_vendor = "apple"), not(target_os = "windows")))]
-fn _du_d_flag(s: String) {
+fn _du_d_flag(s: &str) {
     // MS-WSL linux has altered expected output
     if !is_wsl() {
         assert_eq!(s, "28\t./subdir\n36\t./\n");
@@ -167,10 +166,11 @@ fn _du_d_flag(s: String) {
 fn test_du_h_flag_empty_file() {
     let ts = TestScenario::new("du");
 
-    let result = ts.ucmd().arg("-h").arg("empty.txt").run();
-    assert!(result.success);
-    assert_eq!(result.stderr, "");
-    assert_eq!(result.stdout, "0\tempty.txt\n");
+    ts.ucmd()
+        .arg("-h")
+        .arg("empty.txt")
+        .succeeds()
+        .stdout_only("0\tempty.txt\n");
 }
 
 #[cfg(feature = "touch")]