Fix up some warnings and move integration tests to correct dir

src/cli.rs

@@ -35,7 +35,7 @@ impl<T> MaybeOwned<'a, T> {
     }
 }
 
-pub async fn cli() -> Result<(), Box<Error>> {
+pub async fn cli() -> Result<(), Box<dyn Error>> {
     let mut context = Context::basic()?;
 
     {

src/context.rs

@@ -12,7 +12,7 @@ pub struct Context {
 }
 
 impl Context {
-    crate fn basic() -> Result<Context, Box<Error>> {
+    crate fn basic() -> Result<Context, Box<dyn Error>> {
         Ok(Context {
             commands: indexmap::IndexMap::new(),
             host: Arc::new(Mutex::new(crate::env::host::BasicHost)),

src/main.rs

@@ -17,13 +17,12 @@ mod parser;
 mod prelude;
 mod shell;
 mod stream;
-mod tests;
 
 use clap::{App, Arg};
 use log::LevelFilter;
 use std::error::Error;
 
-fn main() -> Result<(), Box<Error>> {
+fn main() -> Result<(), Box<dyn Error>> {
     let matches = App::new("nu shell")
         .version("0.5")
         .arg(