tests: explicitly add isControl and isPrint test

Author: wooster0

lib/std/ascii.zig

@@ -250,6 +250,12 @@ test "ASCII character classes" {
     try testing.expect(!isPrint(control_code.esc));
 }
 
+test "isControl and isPrint compatibility" {
+    var char: u8 = 0;
+    while (char < 255) : (char += 1)
+        try std.testing.expectEqual(isControl(char), !isPrint(char));
+}
+
 /// Writes a lower case copy of `ascii_string` to `output`.
 /// Asserts `output.len >= ascii_string.len`.
 pub fn lowerString(output: []u8, ascii_string: []const u8) []u8 {