add test for non-Windows

isatty_non_windows_test.go

@@ -0,0 +1,14 @@
+// +build !windows
+
+package isatty
+
+import (
+	"os"
+	"testing"
+)
+
+func TestCygwinPipeName(t *testing.T) {
+	if IsCygwinTerminal(os.Stdout.Fd()) {
+		t.Fatal("should be false always")
+	}
+}