Add insert/update to lists (#4873)

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

@@ -26,3 +26,51 @@ fn insert_the_column_conflict() {
 
     assert!(actual.err.contains("column already exists"));
 }
+
+#[test]
+fn insert_into_list() {
+    let actual = nu!(
+        cwd: ".", pipeline(
+        r#"
+            [1, 2, 3] | insert 1 abc | to json -r
+        "#
+    ));
+
+    assert_eq!(actual.out, r#"[1,"abc",2,3]"#);
+}
+
+#[test]
+fn insert_into_list_begin() {
+    let actual = nu!(
+        cwd: ".", pipeline(
+        r#"
+            [1, 2, 3] | insert 0 abc | to json -r
+        "#
+    ));
+
+    assert_eq!(actual.out, r#"["abc",1,2,3]"#);
+}
+
+#[test]
+fn insert_into_list_end() {
+    let actual = nu!(
+        cwd: ".", pipeline(
+        r#"
+            [1, 2, 3] | insert 3 abc | to json -r
+        "#
+    ));
+
+    assert_eq!(actual.out, r#"[1,2,3,"abc"]"#);
+}
+
+#[test]
+fn insert_past_end_list() {
+    let actual = nu!(
+        cwd: ".", pipeline(
+        r#"
+            [1, 2, 3] | insert 5 abc | to json -r
+        "#
+    ));
+
+    assert_eq!(actual.out, r#"[1,2,3,null,null,"abc"]"#);
+}