tests/fold: add tests for non-utf8 streams

tests/by-util/test_fold.rs

@@ -554,3 +554,30 @@ fn test_obsolete_syntax() {
         .succeeds()
         .stdout_is("test1\n \ntest2\n \ntest3\n \ntest4\n \ntest5\n \ntest6\n ");
 }
+#[test]
+fn test_byte_break_at_non_utf8_character() {
+    new_ucmd!()
+        .arg("-b")
+        .arg("-s")
+        .arg("-w")
+        .arg("40")
+        .arg("non_utf8.input")
+        .succeeds()
+        .stdout_is_fixture_bytes("non_utf8.expected");
+}
+#[test]
+fn test_tab_advances_at_non_utf8_character() {
+    new_ucmd!()
+        .arg("-w8")
+        .arg("non_utf8_tab_stops.input")
+        .succeeds()
+        .stdout_is_fixture_bytes("non_utf8_tab_stops_w8.expected");
+}
+#[test]
+fn test_all_tab_advances_at_non_utf8_character() {
+    new_ucmd!()
+        .arg("-w16")
+        .arg("non_utf8_tab_stops.input")
+        .succeeds()
+        .stdout_is_fixture_bytes("non_utf8_tab_stops_w16.expected");
+}

tests/fixtures/fold/non_utf8.expected

@@ -0,0 +1,2 @@
+Alle Menschen sind frei und gleich an 
+Würde und Rechten geboren

tests/fixtures/fold/non_utf8.input

@@ -0,0 +1 @@
+Alle Menschen sind frei und gleich an Würde und Rechten geboren

tests/fixtures/fold/non_utf8_tab_stops.input

@@ -0,0 +1,11 @@
+ﾀ
+ﾀﾁ
+ﾀﾁﾂ
+ﾀﾁﾂﾃ
+ﾀﾁﾂﾃﾄ
+ﾀﾁﾂﾃﾄﾅ
+ﾀﾁﾂﾃﾄﾅﾆ
+ﾀﾁﾂﾃﾄﾅﾆﾇ
+ﾀﾁﾂﾃﾄﾅﾆﾇﾈ
+ﾀﾁﾂﾃﾄﾅﾆﾇ	ﾈ
+ﾀﾁﾂﾃﾄﾅﾆﾇ	ﾈ	ﾉ

tests/fixtures/fold/non_utf8_tab_stops_w16.expected

@@ -0,0 +1,13 @@
+ﾀ
+ﾀﾁ
+ﾀﾁﾂ
+ﾀﾁﾂﾃ
+ﾀﾁﾂﾃﾄ
+ﾀﾁﾂﾃﾄﾅ
+ﾀﾁﾂﾃﾄﾅﾆ
+ﾀﾁﾂﾃﾄﾅﾆﾇ
+ﾀﾁﾂﾃﾄﾅﾆﾇﾈ
+ﾀﾁﾂﾃﾄﾅﾆﾇ	
+ﾈ
+ﾀﾁﾂﾃﾄﾅﾆﾇ	
+ﾈ	ﾉ

tests/fixtures/fold/non_utf8_tab_stops_w8.expected

@@ -0,0 +1,17 @@
+А
+АБ
+АБВ
+АБВГ
+АБВГД
+АБВГДЕ
+АБВГДЕЖ
+АБВГДЕЖЗ
+АБВГДЕЖЗ
+И
+АБВГДЕЖЗ
+	
+И
+АБВГДЕЖЗ
+	
+И	
+Й