Semicolon (#1613)

* WIP on blocks

* Getting further

* add some tests

crates/nu-cli/tests/commands/mod.rs

@@ -30,6 +30,7 @@ mod rename;
 mod reverse;
 mod rm;
 mod save;
+mod semicolon;
 mod sort_by;
 mod split_by;
 mod split_column;

crates/nu-cli/tests/commands/semicolon.rs

@@ -0,0 +1,29 @@
+use nu_test_support::playground::Playground;
+use nu_test_support::{nu, pipeline};
+
+#[test]
+fn semicolon_allows_lhs_to_complete() {
+    Playground::setup("create_test_1", |dirs, _sandbox| {
+        let actual = nu!(
+            cwd: dirs.test(),
+            "touch i_will_be_created_semi.txt; echo done"
+        );
+
+        let path = dirs.test().join("i_will_be_created_semi.txt");
+
+        assert!(path.exists());
+        assert_eq!(actual, "done");
+    })
+}
+
+#[test]
+fn semicolon_lhs_error_stops_processing() {
+    let actual = nu!(
+    cwd: "tests/fixtures/formats", pipeline(
+    r#"
+        where 1 1; echo done
+    "#
+    ));
+
+    assert!(!actual.contains("done"));
+}