Rename the use of invocation to subexpression (#3568)

* Rename the use of invocation to subexpression

* Fix test name

crates/nu-engine/src/evaluate/evaluator.rs

@@ -37,7 +37,7 @@ pub fn evaluate_baseline_expr(
         }
         Expression::Variable(var, s) => evaluate_reference(&var, ctx, *s),
         Expression::Command => unimplemented!(),
-        Expression::Invocation(block) => evaluate_invocation(block, ctx),
+        Expression::Subexpression(block) => evaluate_subexpression(block, ctx),
         Expression::ExternalCommand(_) => unimplemented!(),
         Expression::Binary(binary) => {
             // TODO: If we want to add short-circuiting, we'll need to move these down
@@ -277,7 +277,10 @@ fn evaluate_reference(
     }
 }
 
-fn evaluate_invocation(block: &hir::Block, ctx: &EvaluationContext) -> Result<Value, ShellError> {
+fn evaluate_subexpression(
+    block: &hir::Block,
+    ctx: &EvaluationContext,
+) -> Result<Value, ShellError> {
     // FIXME: we should use a real context here
     let input = match ctx.scope.get_var("$it") {
         Some(it) => InputStream::one(it),

crates/nu-engine/tests/evaluate/mod.rs

@@ -1,3 +1,3 @@
-mod invocation;
 mod operator;
+mod subexpression;
 mod variables;

crates/nu-engine/tests/evaluate/subexpression.rs

@@ -1,7 +1,7 @@
 use nu_test_support::nu;
 
 #[test]
-fn test_parse_invocation_with_range() {
+fn test_parse_subexpression_with_range() {
     let actual = nu!(
         cwd: ".",
         r#"