Allow expanding aliases before keywords, improve hiding (#4858)

* Allow aliasing source

* Add test

* improve hiding

* Finish adding tests

* fix test

crates/nu-command/src/core_commands/hide.rs

@@ -113,7 +113,7 @@ impl Command for Hide {
         } else if !import_pattern.hidden.contains(&import_pattern.head.name)
             && stack.remove_env_var(engine_state, &head_name_str).is_none()
         {
-            return Err(ShellError::NotFound(call.positional[0].span));
+            // TODO: we may want to error in the future
         }
 
         Ok(PipelineData::new(call.head))

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

@@ -0,0 +1,40 @@
+use nu_test_support::{nu, pipeline};
+
+#[test]
+fn alias_simple() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+        alias bar = source sample_def.nu; bar; greet
+        "#
+    ));
+
+    assert_eq!(actual.out, "hello");
+}
+
+#[test]
+fn alias_hiding1() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+        source ./activate-foo.nu;
+        $nu.scope.aliases | find deactivate-foo | length
+        "#
+    ));
+
+    assert_eq!(actual.out, "1");
+}
+
+#[test]
+fn alias_hiding2() {
+    let actual = nu!(
+        cwd: "tests/fixtures/formats", pipeline(
+        r#"
+        source ./activate-foo.nu;
+        deactivate-foo;
+        $nu.scope.aliases | find deactivate-foo | length
+        "#
+    ));
+
+    assert_eq!(actual.out, "0");
+}

crates/nu-command/tests/commands/math/avg.rs

@@ -18,8 +18,8 @@ fn can_average_numbers() {
 fn can_average_bytes() {
     let actual = nu!(
         cwd: "tests/fixtures/formats",
-        "ls | sort-by name | skip 1 | first 2 | get size | math avg | to json -r"
+        "[100kb, 10b, 100mib] | math avg | to json -r"
     );
 
-    assert_eq!(actual.out, "1600");
+    assert_eq!(actual.out, "34985870");
 }

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

@@ -1,3 +1,4 @@
+mod alias;
 mod all;
 mod any;
 mod append;