sort: dedup using compare_by (#2064)

compare_by is the function used for sorting, we should use it for dedup
as well.

tests/by-util/test_sort.rs

@@ -223,6 +223,16 @@ fn test_mixed_floats_ints_chars_numeric_unique() {
     test_helper("mixed_floats_ints_chars_numeric_unique", "-nu");
 }
 
+#[test]
+fn test_words_unique() {
+    test_helper("words_unique", "-u");
+}
+
+#[test]
+fn test_numeric_unique() {
+    test_helper("numeric_unique", "-nu");
+}
+
 #[test]
 fn test_mixed_floats_ints_chars_numeric_reverse() {
     test_helper("mixed_floats_ints_chars_numeric_unique_reverse", "-nur");

tests/fixtures/sort/numeric_unique.expected

@@ -0,0 +1,2 @@
+-10 bb
+aa

tests/fixtures/sort/numeric_unique.txt

@@ -0,0 +1,3 @@
+aa
+-10 bb
+-10 aa

tests/fixtures/sort/words_unique.expected

@@ -0,0 +1,3 @@
+aaa
+bbb
+zzz

tests/fixtures/sort/words_unique.txt

@@ -0,0 +1,4 @@
+zzz
+aaa
+bbb
+bbb