Adopt the Rust test builtin

This switches the builtin test implementation from C++ to Rust

fish-rust/src/builtins/shared.rs

@@ -183,6 +183,7 @@ pub fn run_builtin(
         RustBuiltin::Random => super::random::random(parser, streams, args),
         RustBuiltin::Realpath => super::realpath::realpath(parser, streams, args),
         RustBuiltin::Return => super::r#return::r#return(parser, streams, args),
+        RustBuiltin::Test => super::test::test(parser, streams, args),
         RustBuiltin::Type => super::r#type::r#type(parser, streams, args),
         RustBuiltin::Wait => wait::wait(parser, streams, args),
         RustBuiltin::Printf => printf::printf(parser, streams, args),

src/builtin.cpp

@@ -562,6 +562,9 @@ static maybe_t<RustBuiltin> try_get_rust_builtin(const wcstring &cmd) {
     if (cmd == L"realpath") {
         return RustBuiltin::Realpath;
     }
+    if (cmd == L"test" || cmd == L"[") {
+        return RustBuiltin::Test;
+    }
     if (cmd == L"type") {
         return RustBuiltin::Type;
     }

src/builtin.h

@@ -127,6 +127,7 @@ enum class RustBuiltin : int32_t {
     Random,
     Realpath,
     Return,
+    Test,
     Type,
     Wait,
 };