[from/to]tsv support.

tests/command_open_tests.rs

@@ -68,6 +68,21 @@ fn open_can_parse_toml() {
     assert_eq!(actual, "2018");
 }
 
+#[test]
+fn open_can_parse_tsv() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", h::pipeline(
+        r#"
+            open caco3_plastics.tsv
+            | first 1 
+            | get origin 
+            | echo $it
+        "#
+    ));
+
+    assert_eq!(actual, "SPAIN")
+}
+
 #[test]
 fn open_can_parse_json() {
     let actual = nu!(