Command tests (#922)

* WIP command tests

* Finish marking todo tests

* update

* update

* Windows cd test ignoring

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

@@ -0,0 +1,72 @@
+use nu_test_support::{nu, pipeline};
+
+// FIXME: jt: needs more work
+#[ignore]
+#[test]
+fn columns() {
+    let actual = nu!(
+        cwd: ".", pipeline(r#"
+            echo [
+              [arepas, color];
+
+              [3,  white]
+              [8, yellow]
+              [4,  white]
+            ]
+            | drop column
+            | get
+            | length
+        "#)
+    );
+
+    assert_eq!(actual.out, "1");
+}
+
+// FIXME: jt: needs more work
+#[ignore]
+#[test]
+fn more_columns_than_table_has() {
+    let actual = nu!(
+        cwd: ".", pipeline(r#"
+            echo [
+              [arepas, color];
+
+              [3,  white]
+              [8, yellow]
+              [4,  white]
+            ]
+            | drop column 3
+            | get
+            | empty?
+        "#)
+    );
+
+    assert_eq!(actual.out, "true");
+}
+
+#[test]
+fn rows() {
+    let actual = nu!(
+        cwd: ".", pipeline(r#"
+            echo [
+              [arepas];
+
+              [3]
+              [8]
+              [4]
+            ]
+            | drop 2
+            | get arepas
+            | math sum
+        "#)
+    );
+
+    assert_eq!(actual.out, "3");
+}
+
+#[test]
+fn more_rows_than_table_has() {
+    let actual = nu!(cwd: ".", "date | drop 50 | length");
+
+    assert_eq!(actual.out, "0");
+}