Nullify --nth option when it's irrelevant

1 files changed, 35 insertions, 5 deletions

diff --git a/src/options_test.go b/src/options_test.go
index e10ec569..782ad791 100644
--- a/src/options_test.go
+++ b/src/options_test.go
@@ -21,17 +21,47 @@ func TestSplitNth(t *testing.T) {
 		}
 	}
 	{
-		ranges := splitNth("..3,1..,2..3,4..-1,-3..-2,..,2,-2")
-		if len(ranges) != 8 ||
+		ranges := splitNth("..3,1..,2..3,4..-1,-3..-2,..,2,-2,2..-2,1..-1")
+		if len(ranges) != 10 ||
 			ranges[0].begin != rangeEllipsis || ranges[0].end != 3 ||
-			ranges[1].begin != 1 || ranges[1].end != rangeEllipsis ||
+			ranges[1].begin != rangeEllipsis || ranges[1].end != rangeEllipsis ||
 			ranges[2].begin != 2 || ranges[2].end != 3 ||
-			ranges[3].begin != 4 || ranges[3].end != -1 ||
+			ranges[3].begin != 4 || ranges[3].end != rangeEllipsis ||
 			ranges[4].begin != -3 || ranges[4].end != -2 ||
 			ranges[5].begin != rangeEllipsis || ranges[5].end != rangeEllipsis ||
 			ranges[6].begin != 2 || ranges[6].end != 2 ||
-			ranges[7].begin != -2 || ranges[7].end != -2 {
+			ranges[7].begin != -2 || ranges[7].end != -2 ||
+			ranges[8].begin != 2 || ranges[8].end != -2 ||
+			ranges[9].begin != rangeEllipsis || ranges[9].end != rangeEllipsis {
 			t.Errorf("%s", ranges)
 		}
 	}
 }
+
+func TestIrrelevantNth(t *testing.T) {
+	{
+		opts := defaultOptions()
+		words := []string{"--nth", "..", "-x"}
+		parseOptions(opts, words)
+		if len(opts.Nth) != 0 {
+			t.Errorf("nth should be empty: %s", opts.Nth)
+		}
+	}
+	for _, words := range [][]string{[]string{"--nth", "..,3"}, []string{"--nth", "3,1.."}, []string{"--nth", "..-1,1"}} {
+		{
+			opts := defaultOptions()
+			parseOptions(opts, words)
+			if len(opts.Nth) != 0 {
+				t.Errorf("nth should be empty: %s", opts.Nth)
+			}
+		}
+		{
+			opts := defaultOptions()
+			words = append(words, "-x")
+			parseOptions(opts, words)
+			if len(opts.Nth) != 2 {
+				t.Errorf("nth should not be empty: %s", opts.Nth)
+			}
+		}
+	}
+}