Fix type() error message and BaseException.__str__

Lib/test/test_types.py

@@ -1168,8 +1168,6 @@ class ClassCreationTests(unittest.TestCase):
         with self.assertRaises(TypeError):
             X = types.new_class("X", (int(), C))
 
-    # TODO: RUSTPYTHON
-    @unittest.expectedFailure
     def test_one_argument_type(self):
         expected_message = 'type.__new__() takes exactly 3 arguments (1 given)'
 

tests/snippets/exceptions.py

@@ -15,6 +15,8 @@ exc = KeyError('message')
 assert str(exc) == "'message'"
 assert round_trip_repr(exc)
 
+assert LookupError.__str__(exc) == "message"
+
 exc = KeyError('message', 'another message')
 assert str(exc) == "('message', 'another message')"
 assert round_trip_repr(exc)

vm/src/exceptions.rs

@@ -131,7 +131,7 @@ impl PyBaseException {
 
     #[pymethod(name = "__str__")]
     fn str(&self, vm: &VirtualMachine) -> PyStringRef {
-        let str_args = exception_args_as_string(vm, self.args(), false);
+        let str_args = exception_args_as_string(vm, self.args(), true);
         match str_args.into_iter().exactly_one() {
             Err(i) if i.len() == 0 => PyString::from("").into_ref(vm),
             Ok(s) => s,
@@ -616,6 +616,18 @@ fn make_arg_getter(idx: usize) -> impl Fn(PyBaseExceptionRef, &VirtualMachine) -
     }
 }
 
+fn key_error_str(exc: PyBaseExceptionRef, vm: &VirtualMachine) -> PyStringRef {
+    let args = exc.args();
+    if args.as_slice().len() == 1 {
+        exception_args_as_string(vm, args, false)
+            .into_iter()
+            .exactly_one()
+            .unwrap()
+    } else {
+        exc.str(vm)
+    }
+}
+
 pub fn init(ctx: &PyContext) {
     let excs = &ctx.exceptions;
 
@@ -638,6 +650,10 @@ pub fn init(ctx: &PyContext) {
         "value" => ctx.new_property(make_arg_getter(0)),
     });
 
+    extend_class!(ctx, &excs.key_error, {
+        "__str__" => ctx.new_method(key_error_str),
+    });
+
     extend_class!(ctx, &excs.unicode_decode_error, {
         "encoding" => ctx.new_property(make_arg_getter(0)),
         "object" => ctx.new_property(make_arg_getter(1)),

vm/src/obj/objtype.rs

@@ -254,13 +254,20 @@ impl PyClassRef {
     fn tp_new(metatype: PyClassRef, args: PyFuncArgs, vm: &VirtualMachine) -> PyResult {
         vm_trace!("type.__new__ {:?}", args);
 
-        if metatype.is(&vm.ctx.types.type_type) {
-            if args.args.len() == 1 && args.kwargs.is_empty() {
-                return Ok(args.args[0].class().into_object());
-            }
-            if args.args.len() != 3 {
-                return Err(vm.new_type_error("type() takes 1 or 3 arguments".to_string()));
-            }
+        let is_type_type = metatype.is(&vm.ctx.types.type_type);
+        if is_type_type && args.args.len() == 1 && args.kwargs.is_empty() {
+            return Ok(args.args[0].class().into_object());
+        }
+
+        if args.args.len() != 3 {
+            return Err(vm.new_type_error(if is_type_type {
+                "type() takes 1 or 3 arguments".to_string()
+            } else {
+                format!(
+                    "type.__new__() takes exactly 3 arguments ({} given)",
+                    args.args.len()
+                )
+            }));
         }
 
         let (name, bases, dict): (PyStringRef, PyIterable<PyClassRef>, PyDictRef) =