test: add test cases for issue #22

tests/issue_22.rs

@@ -0,0 +1,24 @@
+use orgize::Org;
+
+#[test]
+fn whitespaces() {
+    let org = Org::parse("       ");
+
+    assert(&org);
+
+    let org = Org::parse("\t \t  \n \t \t \n  \t");
+
+    assert(&org);
+
+    let org = Org::parse("\u{000b}\u{0085}\u{00a0}\u{1680}\u{2000}\u{2001}\u{2002}\u{2003}\u{2004}\u{2005}\u{2006}\u{2007}\u{2008}\u{2009}\u{200a}\u{2028}\u{2029}\u{202f}\u{205f}\u{3000}");
+
+    assert(&org);
+}
+
+fn assert(org: &Org) {
+    assert_eq!(
+        org.iter().count(),
+        2,
+        "should contains only one element - document"
+    );
+}