Command tests (#922)

* WIP command tests

* Finish marking todo tests

* update

* update

* Windows cd test ignoring

crates/nu-command/tests/commands/lines.rs

@@ -0,0 +1,54 @@
+use nu_test_support::{nu, pipeline};
+
+#[test]
+fn lines() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+            open cargo_sample.toml -r
+            | lines
+            | skip while $it != "[dependencies]"
+            | skip 1
+            | first 1
+            | split column "="
+            | get Column1
+            | str trim
+        "#
+    ));
+
+    assert_eq!(actual.out, "rustyline");
+}
+
+// FIXME: jt: needs more work
+#[ignore]
+#[test]
+fn lines_proper_buffering() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+            open lines_test.txt -r
+            | lines
+            | str length
+            | to json
+        "#
+    ));
+
+    assert_eq!(actual.out, "[8193,3]");
+}
+
+// FIXME: jt: needs more work
+#[ignore]
+#[test]
+fn lines_multi_value_split() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+            open sample-simple.json
+            | get first second
+            | lines
+            | length
+        "#
+    ));
+
+    assert_eq!(actual.out, "5");
+}