Command tests (#922)

* WIP command tests

* Finish marking todo tests

* update

* update

* Windows cd test ignoring

crates/nu-command/tests/commands/random/bool.rs

@@ -0,0 +1,16 @@
+use nu_test_support::{nu, pipeline};
+
+#[test]
+fn generates_a_bool() {
+    let actual = nu!(
+        cwd: ".", pipeline(
+        r#"
+        random bool
+        "#
+    ));
+
+    let output = actual.out;
+    let is_boolean_output = output == "true" || output == "false";
+
+    assert!(is_boolean_output);
+}