First stab at comprehensive IO::Handle.lines tests

Unfortunately, a skip was already needed.  :-(

S16-io/lines.t

@@ -0,0 +1,73 @@
+use v6;
+use Test;
+
+my @endings =
+  "\n"   => "LF",
+  "\r\n" => "CRLF",
+#  "\r"   => "CR",   # CR later
+                     # other line endings later still
+;
+
+plan @endings * (1 + 3 * ( (3 * 7) + 7));
+
+my $filename = 't/spec/S16-io/lines.testing';
+my @text = <zero one two three four>;
+
+for @endings -> (:key($eol), :value($EOL)) {
+    unlink $filename;  # make sure spurt will work
+
+    my $text = @text.join($eol);
+    ok $filename.IO.spurt($text), "could we spurt a file with $EOL";
+
+    for (), '', :chomp, '', :!chomp, $eol -> $chomp, $end {
+        my $status = "{$chomp.gist} / $EOL";
+
+        for (), True, :close, False, :!close, True -> $closing, $open {
+            my $handle = open($filename, |$chomp);
+            isa-ok $handle, IO::Handle;
+
+            my $status = OUTER::<$status> ~ " / {$open ?? 'open' !! 'close'}";
+
+            my $first;
+            for $handle.lines -> $line {
+                is $line,"@text[0]$end", "read first line: $status";
+                $first = $line;
+                last;
+            }
+
+            is $handle.ins, 1, "read one line: $status";
+            my @lines = $first, |$handle.lines(|$closing);
+            is @lines.join, @text.join($end), "rest of file: $status";
+
+            is $handle.ins, ($open ?? 5 !! 1), "read five lines: $status";
+            is $handle.opened, $open, "handle still open: $status";
+            ok $handle.close, "closed handle: $status";
+        }
+
+        # slicing
+        my $handle = open($filename, |$chomp);
+        isa-ok $handle, IO::Handle;
+
+        my @lines = $handle.lines[1,2];
+        is @lines.join, @text[1,2].join($end) ~ $end, "handle 1,2: $status";
+        is $handle.ins, 3, "handle read three lines: $status";
+
+        is $handle.lines[*-1], @text[*-1], "handle last line: $status";
+
+        # slicing on IO::Path
+        #?rakudo skip "Reading from filehandle failed: bad file descriptor"
+        is $filename.IO.lines(|$chomp)[1,2].join($end),
+          @text[1,2].join($end) ~ $end,
+          "path 1,2: $status";
+
+        is $filename.IO.lines(|$chomp)[*-1],
+          @text[*-1],
+          "path last line: $status";
+
+        is $filename.IO.lines(|$chomp).elems, +@text, "path elems: $status";
+    }
+}
+
+unlink $filename; # cleanup
+
+# vim: ft=perl6